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1da177e4 LT |
1 | /* |
2 | * linux/kernel/timer.c | |
3 | * | |
4a22f166 | 4 | * Kernel internal timers |
1da177e4 LT |
5 | * |
6 | * Copyright (C) 1991, 1992 Linus Torvalds | |
7 | * | |
8 | * 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better. | |
9 | * | |
10 | * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 | |
11 | * "A Kernel Model for Precision Timekeeping" by Dave Mills | |
12 | * 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to | |
13 | * serialize accesses to xtime/lost_ticks). | |
14 | * Copyright (C) 1998 Andrea Arcangeli | |
15 | * 1999-03-10 Improved NTP compatibility by Ulrich Windl | |
16 | * 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love | |
17 | * 2000-10-05 Implemented scalable SMP per-CPU timer handling. | |
18 | * Copyright (C) 2000, 2001, 2002 Ingo Molnar | |
19 | * Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar | |
20 | */ | |
21 | ||
22 | #include <linux/kernel_stat.h> | |
9984de1a | 23 | #include <linux/export.h> |
1da177e4 LT |
24 | #include <linux/interrupt.h> |
25 | #include <linux/percpu.h> | |
26 | #include <linux/init.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/swap.h> | |
b488893a | 29 | #include <linux/pid_namespace.h> |
1da177e4 LT |
30 | #include <linux/notifier.h> |
31 | #include <linux/thread_info.h> | |
32 | #include <linux/time.h> | |
33 | #include <linux/jiffies.h> | |
34 | #include <linux/posix-timers.h> | |
35 | #include <linux/cpu.h> | |
36 | #include <linux/syscalls.h> | |
97a41e26 | 37 | #include <linux/delay.h> |
79bf2bb3 | 38 | #include <linux/tick.h> |
82f67cd9 | 39 | #include <linux/kallsyms.h> |
e360adbe | 40 | #include <linux/irq_work.h> |
eea08f32 | 41 | #include <linux/sched.h> |
cf4aebc2 | 42 | #include <linux/sched/sysctl.h> |
5a0e3ad6 | 43 | #include <linux/slab.h> |
1a0df594 | 44 | #include <linux/compat.h> |
1da177e4 | 45 | |
7c0f6ba6 | 46 | #include <linux/uaccess.h> |
1da177e4 LT |
47 | #include <asm/unistd.h> |
48 | #include <asm/div64.h> | |
49 | #include <asm/timex.h> | |
50 | #include <asm/io.h> | |
51 | ||
c1ad348b TG |
52 | #include "tick-internal.h" |
53 | ||
2b022e3d XG |
54 | #define CREATE_TRACE_POINTS |
55 | #include <trace/events/timer.h> | |
56 | ||
40747ffa | 57 | __visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; |
ecea8d19 TG |
58 | |
59 | EXPORT_SYMBOL(jiffies_64); | |
60 | ||
1da177e4 | 61 | /* |
500462a9 TG |
62 | * The timer wheel has LVL_DEPTH array levels. Each level provides an array of |
63 | * LVL_SIZE buckets. Each level is driven by its own clock and therefor each | |
64 | * level has a different granularity. | |
65 | * | |
66 | * The level granularity is: LVL_CLK_DIV ^ lvl | |
67 | * The level clock frequency is: HZ / (LVL_CLK_DIV ^ level) | |
68 | * | |
69 | * The array level of a newly armed timer depends on the relative expiry | |
70 | * time. The farther the expiry time is away the higher the array level and | |
71 | * therefor the granularity becomes. | |
72 | * | |
73 | * Contrary to the original timer wheel implementation, which aims for 'exact' | |
74 | * expiry of the timers, this implementation removes the need for recascading | |
75 | * the timers into the lower array levels. The previous 'classic' timer wheel | |
76 | * implementation of the kernel already violated the 'exact' expiry by adding | |
77 | * slack to the expiry time to provide batched expiration. The granularity | |
78 | * levels provide implicit batching. | |
79 | * | |
80 | * This is an optimization of the original timer wheel implementation for the | |
81 | * majority of the timer wheel use cases: timeouts. The vast majority of | |
82 | * timeout timers (networking, disk I/O ...) are canceled before expiry. If | |
83 | * the timeout expires it indicates that normal operation is disturbed, so it | |
84 | * does not matter much whether the timeout comes with a slight delay. | |
85 | * | |
86 | * The only exception to this are networking timers with a small expiry | |
87 | * time. They rely on the granularity. Those fit into the first wheel level, | |
88 | * which has HZ granularity. | |
89 | * | |
90 | * We don't have cascading anymore. timers with a expiry time above the | |
91 | * capacity of the last wheel level are force expired at the maximum timeout | |
92 | * value of the last wheel level. From data sampling we know that the maximum | |
93 | * value observed is 5 days (network connection tracking), so this should not | |
94 | * be an issue. | |
95 | * | |
96 | * The currently chosen array constants values are a good compromise between | |
97 | * array size and granularity. | |
98 | * | |
99 | * This results in the following granularity and range levels: | |
100 | * | |
101 | * HZ 1000 steps | |
102 | * Level Offset Granularity Range | |
103 | * 0 0 1 ms 0 ms - 63 ms | |
104 | * 1 64 8 ms 64 ms - 511 ms | |
105 | * 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s) | |
106 | * 3 192 512 ms 4096 ms - 32767 ms (~4s - ~32s) | |
107 | * 4 256 4096 ms (~4s) 32768 ms - 262143 ms (~32s - ~4m) | |
108 | * 5 320 32768 ms (~32s) 262144 ms - 2097151 ms (~4m - ~34m) | |
109 | * 6 384 262144 ms (~4m) 2097152 ms - 16777215 ms (~34m - ~4h) | |
110 | * 7 448 2097152 ms (~34m) 16777216 ms - 134217727 ms (~4h - ~1d) | |
111 | * 8 512 16777216 ms (~4h) 134217728 ms - 1073741822 ms (~1d - ~12d) | |
112 | * | |
113 | * HZ 300 | |
114 | * Level Offset Granularity Range | |
115 | * 0 0 3 ms 0 ms - 210 ms | |
116 | * 1 64 26 ms 213 ms - 1703 ms (213ms - ~1s) | |
117 | * 2 128 213 ms 1706 ms - 13650 ms (~1s - ~13s) | |
118 | * 3 192 1706 ms (~1s) 13653 ms - 109223 ms (~13s - ~1m) | |
119 | * 4 256 13653 ms (~13s) 109226 ms - 873810 ms (~1m - ~14m) | |
120 | * 5 320 109226 ms (~1m) 873813 ms - 6990503 ms (~14m - ~1h) | |
121 | * 6 384 873813 ms (~14m) 6990506 ms - 55924050 ms (~1h - ~15h) | |
122 | * 7 448 6990506 ms (~1h) 55924053 ms - 447392423 ms (~15h - ~5d) | |
123 | * 8 512 55924053 ms (~15h) 447392426 ms - 3579139406 ms (~5d - ~41d) | |
124 | * | |
125 | * HZ 250 | |
126 | * Level Offset Granularity Range | |
127 | * 0 0 4 ms 0 ms - 255 ms | |
128 | * 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s) | |
129 | * 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s) | |
130 | * 3 192 2048 ms (~2s) 16384 ms - 131071 ms (~16s - ~2m) | |
131 | * 4 256 16384 ms (~16s) 131072 ms - 1048575 ms (~2m - ~17m) | |
132 | * 5 320 131072 ms (~2m) 1048576 ms - 8388607 ms (~17m - ~2h) | |
133 | * 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h) | |
134 | * 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d) | |
135 | * 8 512 67108864 ms (~18h) 536870912 ms - 4294967288 ms (~6d - ~49d) | |
136 | * | |
137 | * HZ 100 | |
138 | * Level Offset Granularity Range | |
139 | * 0 0 10 ms 0 ms - 630 ms | |
140 | * 1 64 80 ms 640 ms - 5110 ms (640ms - ~5s) | |
141 | * 2 128 640 ms 5120 ms - 40950 ms (~5s - ~40s) | |
142 | * 3 192 5120 ms (~5s) 40960 ms - 327670 ms (~40s - ~5m) | |
143 | * 4 256 40960 ms (~40s) 327680 ms - 2621430 ms (~5m - ~43m) | |
144 | * 5 320 327680 ms (~5m) 2621440 ms - 20971510 ms (~43m - ~5h) | |
145 | * 6 384 2621440 ms (~43m) 20971520 ms - 167772150 ms (~5h - ~1d) | |
146 | * 7 448 20971520 ms (~5h) 167772160 ms - 1342177270 ms (~1d - ~15d) | |
1da177e4 | 147 | */ |
1da177e4 | 148 | |
500462a9 TG |
149 | /* Clock divisor for the next level */ |
150 | #define LVL_CLK_SHIFT 3 | |
151 | #define LVL_CLK_DIV (1UL << LVL_CLK_SHIFT) | |
152 | #define LVL_CLK_MASK (LVL_CLK_DIV - 1) | |
153 | #define LVL_SHIFT(n) ((n) * LVL_CLK_SHIFT) | |
154 | #define LVL_GRAN(n) (1UL << LVL_SHIFT(n)) | |
1da177e4 | 155 | |
500462a9 TG |
156 | /* |
157 | * The time start value for each level to select the bucket at enqueue | |
158 | * time. | |
159 | */ | |
160 | #define LVL_START(n) ((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT)) | |
161 | ||
162 | /* Size of each clock level */ | |
163 | #define LVL_BITS 6 | |
164 | #define LVL_SIZE (1UL << LVL_BITS) | |
165 | #define LVL_MASK (LVL_SIZE - 1) | |
166 | #define LVL_OFFS(n) ((n) * LVL_SIZE) | |
167 | ||
168 | /* Level depth */ | |
169 | #if HZ > 100 | |
170 | # define LVL_DEPTH 9 | |
171 | # else | |
172 | # define LVL_DEPTH 8 | |
173 | #endif | |
174 | ||
175 | /* The cutoff (max. capacity of the wheel) */ | |
176 | #define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH)) | |
177 | #define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1)) | |
178 | ||
179 | /* | |
180 | * The resulting wheel size. If NOHZ is configured we allocate two | |
181 | * wheels so we have a separate storage for the deferrable timers. | |
182 | */ | |
183 | #define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH) | |
184 | ||
185 | #ifdef CONFIG_NO_HZ_COMMON | |
186 | # define NR_BASES 2 | |
187 | # define BASE_STD 0 | |
188 | # define BASE_DEF 1 | |
189 | #else | |
190 | # define NR_BASES 1 | |
191 | # define BASE_STD 0 | |
192 | # define BASE_DEF 0 | |
193 | #endif | |
1da177e4 | 194 | |
494af3ed | 195 | struct timer_base { |
500462a9 TG |
196 | spinlock_t lock; |
197 | struct timer_list *running_timer; | |
198 | unsigned long clk; | |
a683f390 | 199 | unsigned long next_expiry; |
500462a9 TG |
200 | unsigned int cpu; |
201 | bool migration_enabled; | |
202 | bool nohz_active; | |
a683f390 | 203 | bool is_idle; |
500462a9 TG |
204 | DECLARE_BITMAP(pending_map, WHEEL_SIZE); |
205 | struct hlist_head vectors[WHEEL_SIZE]; | |
6e453a67 | 206 | } ____cacheline_aligned; |
e52b1db3 | 207 | |
500462a9 | 208 | static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]); |
6e453a67 | 209 | |
bc7a34b8 TG |
210 | #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) |
211 | unsigned int sysctl_timer_migration = 1; | |
212 | ||
683be13a | 213 | void timers_update_migration(bool update_nohz) |
bc7a34b8 TG |
214 | { |
215 | bool on = sysctl_timer_migration && tick_nohz_active; | |
216 | unsigned int cpu; | |
217 | ||
218 | /* Avoid the loop, if nothing to update */ | |
500462a9 | 219 | if (this_cpu_read(timer_bases[BASE_STD].migration_enabled) == on) |
bc7a34b8 TG |
220 | return; |
221 | ||
222 | for_each_possible_cpu(cpu) { | |
500462a9 TG |
223 | per_cpu(timer_bases[BASE_STD].migration_enabled, cpu) = on; |
224 | per_cpu(timer_bases[BASE_DEF].migration_enabled, cpu) = on; | |
bc7a34b8 | 225 | per_cpu(hrtimer_bases.migration_enabled, cpu) = on; |
683be13a TG |
226 | if (!update_nohz) |
227 | continue; | |
500462a9 TG |
228 | per_cpu(timer_bases[BASE_STD].nohz_active, cpu) = true; |
229 | per_cpu(timer_bases[BASE_DEF].nohz_active, cpu) = true; | |
683be13a | 230 | per_cpu(hrtimer_bases.nohz_active, cpu) = true; |
bc7a34b8 TG |
231 | } |
232 | } | |
233 | ||
234 | int timer_migration_handler(struct ctl_table *table, int write, | |
235 | void __user *buffer, size_t *lenp, | |
236 | loff_t *ppos) | |
237 | { | |
238 | static DEFINE_MUTEX(mutex); | |
239 | int ret; | |
240 | ||
241 | mutex_lock(&mutex); | |
242 | ret = proc_dointvec(table, write, buffer, lenp, ppos); | |
243 | if (!ret && write) | |
683be13a | 244 | timers_update_migration(false); |
bc7a34b8 TG |
245 | mutex_unlock(&mutex); |
246 | return ret; | |
247 | } | |
bc7a34b8 TG |
248 | #endif |
249 | ||
9c133c46 AS |
250 | static unsigned long round_jiffies_common(unsigned long j, int cpu, |
251 | bool force_up) | |
4c36a5de AV |
252 | { |
253 | int rem; | |
254 | unsigned long original = j; | |
255 | ||
256 | /* | |
257 | * We don't want all cpus firing their timers at once hitting the | |
258 | * same lock or cachelines, so we skew each extra cpu with an extra | |
259 | * 3 jiffies. This 3 jiffies came originally from the mm/ code which | |
260 | * already did this. | |
261 | * The skew is done by adding 3*cpunr, then round, then subtract this | |
262 | * extra offset again. | |
263 | */ | |
264 | j += cpu * 3; | |
265 | ||
266 | rem = j % HZ; | |
267 | ||
268 | /* | |
269 | * If the target jiffie is just after a whole second (which can happen | |
270 | * due to delays of the timer irq, long irq off times etc etc) then | |
271 | * we should round down to the whole second, not up. Use 1/4th second | |
272 | * as cutoff for this rounding as an extreme upper bound for this. | |
9c133c46 | 273 | * But never round down if @force_up is set. |
4c36a5de | 274 | */ |
9c133c46 | 275 | if (rem < HZ/4 && !force_up) /* round down */ |
4c36a5de AV |
276 | j = j - rem; |
277 | else /* round up */ | |
278 | j = j - rem + HZ; | |
279 | ||
280 | /* now that we have rounded, subtract the extra skew again */ | |
281 | j -= cpu * 3; | |
282 | ||
9e04d380 BVA |
283 | /* |
284 | * Make sure j is still in the future. Otherwise return the | |
285 | * unmodified value. | |
286 | */ | |
287 | return time_is_after_jiffies(j) ? j : original; | |
4c36a5de | 288 | } |
9c133c46 AS |
289 | |
290 | /** | |
291 | * __round_jiffies - function to round jiffies to a full second | |
292 | * @j: the time in (absolute) jiffies that should be rounded | |
293 | * @cpu: the processor number on which the timeout will happen | |
294 | * | |
295 | * __round_jiffies() rounds an absolute time in the future (in jiffies) | |
296 | * up or down to (approximately) full seconds. This is useful for timers | |
297 | * for which the exact time they fire does not matter too much, as long as | |
298 | * they fire approximately every X seconds. | |
299 | * | |
300 | * By rounding these timers to whole seconds, all such timers will fire | |
301 | * at the same time, rather than at various times spread out. The goal | |
302 | * of this is to have the CPU wake up less, which saves power. | |
303 | * | |
304 | * The exact rounding is skewed for each processor to avoid all | |
305 | * processors firing at the exact same time, which could lead | |
306 | * to lock contention or spurious cache line bouncing. | |
307 | * | |
308 | * The return value is the rounded version of the @j parameter. | |
309 | */ | |
310 | unsigned long __round_jiffies(unsigned long j, int cpu) | |
311 | { | |
312 | return round_jiffies_common(j, cpu, false); | |
313 | } | |
4c36a5de AV |
314 | EXPORT_SYMBOL_GPL(__round_jiffies); |
315 | ||
316 | /** | |
317 | * __round_jiffies_relative - function to round jiffies to a full second | |
318 | * @j: the time in (relative) jiffies that should be rounded | |
319 | * @cpu: the processor number on which the timeout will happen | |
320 | * | |
72fd4a35 | 321 | * __round_jiffies_relative() rounds a time delta in the future (in jiffies) |
4c36a5de AV |
322 | * up or down to (approximately) full seconds. This is useful for timers |
323 | * for which the exact time they fire does not matter too much, as long as | |
324 | * they fire approximately every X seconds. | |
325 | * | |
326 | * By rounding these timers to whole seconds, all such timers will fire | |
327 | * at the same time, rather than at various times spread out. The goal | |
328 | * of this is to have the CPU wake up less, which saves power. | |
329 | * | |
330 | * The exact rounding is skewed for each processor to avoid all | |
331 | * processors firing at the exact same time, which could lead | |
332 | * to lock contention or spurious cache line bouncing. | |
333 | * | |
72fd4a35 | 334 | * The return value is the rounded version of the @j parameter. |
4c36a5de AV |
335 | */ |
336 | unsigned long __round_jiffies_relative(unsigned long j, int cpu) | |
337 | { | |
9c133c46 AS |
338 | unsigned long j0 = jiffies; |
339 | ||
340 | /* Use j0 because jiffies might change while we run */ | |
341 | return round_jiffies_common(j + j0, cpu, false) - j0; | |
4c36a5de AV |
342 | } |
343 | EXPORT_SYMBOL_GPL(__round_jiffies_relative); | |
344 | ||
345 | /** | |
346 | * round_jiffies - function to round jiffies to a full second | |
347 | * @j: the time in (absolute) jiffies that should be rounded | |
348 | * | |
72fd4a35 | 349 | * round_jiffies() rounds an absolute time in the future (in jiffies) |
4c36a5de AV |
350 | * up or down to (approximately) full seconds. This is useful for timers |
351 | * for which the exact time they fire does not matter too much, as long as | |
352 | * they fire approximately every X seconds. | |
353 | * | |
354 | * By rounding these timers to whole seconds, all such timers will fire | |
355 | * at the same time, rather than at various times spread out. The goal | |
356 | * of this is to have the CPU wake up less, which saves power. | |
357 | * | |
72fd4a35 | 358 | * The return value is the rounded version of the @j parameter. |
4c36a5de AV |
359 | */ |
360 | unsigned long round_jiffies(unsigned long j) | |
361 | { | |
9c133c46 | 362 | return round_jiffies_common(j, raw_smp_processor_id(), false); |
4c36a5de AV |
363 | } |
364 | EXPORT_SYMBOL_GPL(round_jiffies); | |
365 | ||
366 | /** | |
367 | * round_jiffies_relative - function to round jiffies to a full second | |
368 | * @j: the time in (relative) jiffies that should be rounded | |
369 | * | |
72fd4a35 | 370 | * round_jiffies_relative() rounds a time delta in the future (in jiffies) |
4c36a5de AV |
371 | * up or down to (approximately) full seconds. This is useful for timers |
372 | * for which the exact time they fire does not matter too much, as long as | |
373 | * they fire approximately every X seconds. | |
374 | * | |
375 | * By rounding these timers to whole seconds, all such timers will fire | |
376 | * at the same time, rather than at various times spread out. The goal | |
377 | * of this is to have the CPU wake up less, which saves power. | |
378 | * | |
72fd4a35 | 379 | * The return value is the rounded version of the @j parameter. |
4c36a5de AV |
380 | */ |
381 | unsigned long round_jiffies_relative(unsigned long j) | |
382 | { | |
383 | return __round_jiffies_relative(j, raw_smp_processor_id()); | |
384 | } | |
385 | EXPORT_SYMBOL_GPL(round_jiffies_relative); | |
386 | ||
9c133c46 AS |
387 | /** |
388 | * __round_jiffies_up - function to round jiffies up to a full second | |
389 | * @j: the time in (absolute) jiffies that should be rounded | |
390 | * @cpu: the processor number on which the timeout will happen | |
391 | * | |
392 | * This is the same as __round_jiffies() except that it will never | |
393 | * round down. This is useful for timeouts for which the exact time | |
394 | * of firing does not matter too much, as long as they don't fire too | |
395 | * early. | |
396 | */ | |
397 | unsigned long __round_jiffies_up(unsigned long j, int cpu) | |
398 | { | |
399 | return round_jiffies_common(j, cpu, true); | |
400 | } | |
401 | EXPORT_SYMBOL_GPL(__round_jiffies_up); | |
402 | ||
403 | /** | |
404 | * __round_jiffies_up_relative - function to round jiffies up to a full second | |
405 | * @j: the time in (relative) jiffies that should be rounded | |
406 | * @cpu: the processor number on which the timeout will happen | |
407 | * | |
408 | * This is the same as __round_jiffies_relative() except that it will never | |
409 | * round down. This is useful for timeouts for which the exact time | |
410 | * of firing does not matter too much, as long as they don't fire too | |
411 | * early. | |
412 | */ | |
413 | unsigned long __round_jiffies_up_relative(unsigned long j, int cpu) | |
414 | { | |
415 | unsigned long j0 = jiffies; | |
416 | ||
417 | /* Use j0 because jiffies might change while we run */ | |
418 | return round_jiffies_common(j + j0, cpu, true) - j0; | |
419 | } | |
420 | EXPORT_SYMBOL_GPL(__round_jiffies_up_relative); | |
421 | ||
422 | /** | |
423 | * round_jiffies_up - function to round jiffies up to a full second | |
424 | * @j: the time in (absolute) jiffies that should be rounded | |
425 | * | |
426 | * This is the same as round_jiffies() except that it will never | |
427 | * round down. This is useful for timeouts for which the exact time | |
428 | * of firing does not matter too much, as long as they don't fire too | |
429 | * early. | |
430 | */ | |
431 | unsigned long round_jiffies_up(unsigned long j) | |
432 | { | |
433 | return round_jiffies_common(j, raw_smp_processor_id(), true); | |
434 | } | |
435 | EXPORT_SYMBOL_GPL(round_jiffies_up); | |
436 | ||
437 | /** | |
438 | * round_jiffies_up_relative - function to round jiffies up to a full second | |
439 | * @j: the time in (relative) jiffies that should be rounded | |
440 | * | |
441 | * This is the same as round_jiffies_relative() except that it will never | |
442 | * round down. This is useful for timeouts for which the exact time | |
443 | * of firing does not matter too much, as long as they don't fire too | |
444 | * early. | |
445 | */ | |
446 | unsigned long round_jiffies_up_relative(unsigned long j) | |
447 | { | |
448 | return __round_jiffies_up_relative(j, raw_smp_processor_id()); | |
449 | } | |
450 | EXPORT_SYMBOL_GPL(round_jiffies_up_relative); | |
451 | ||
3bbb9ec9 | 452 | |
500462a9 | 453 | static inline unsigned int timer_get_idx(struct timer_list *timer) |
3bbb9ec9 | 454 | { |
500462a9 | 455 | return (timer->flags & TIMER_ARRAYMASK) >> TIMER_ARRAYSHIFT; |
3bbb9ec9 | 456 | } |
3bbb9ec9 | 457 | |
500462a9 | 458 | static inline void timer_set_idx(struct timer_list *timer, unsigned int idx) |
1da177e4 | 459 | { |
500462a9 TG |
460 | timer->flags = (timer->flags & ~TIMER_ARRAYMASK) | |
461 | idx << TIMER_ARRAYSHIFT; | |
462 | } | |
1da177e4 | 463 | |
500462a9 TG |
464 | /* |
465 | * Helper function to calculate the array index for a given expiry | |
466 | * time. | |
467 | */ | |
468 | static inline unsigned calc_index(unsigned expires, unsigned lvl) | |
469 | { | |
470 | expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl); | |
471 | return LVL_OFFS(lvl) + (expires & LVL_MASK); | |
472 | } | |
473 | ||
ffdf0477 | 474 | static int calc_wheel_index(unsigned long expires, unsigned long clk) |
1da177e4 | 475 | { |
ffdf0477 | 476 | unsigned long delta = expires - clk; |
500462a9 TG |
477 | unsigned int idx; |
478 | ||
479 | if (delta < LVL_START(1)) { | |
480 | idx = calc_index(expires, 0); | |
481 | } else if (delta < LVL_START(2)) { | |
482 | idx = calc_index(expires, 1); | |
483 | } else if (delta < LVL_START(3)) { | |
484 | idx = calc_index(expires, 2); | |
485 | } else if (delta < LVL_START(4)) { | |
486 | idx = calc_index(expires, 3); | |
487 | } else if (delta < LVL_START(5)) { | |
488 | idx = calc_index(expires, 4); | |
489 | } else if (delta < LVL_START(6)) { | |
490 | idx = calc_index(expires, 5); | |
491 | } else if (delta < LVL_START(7)) { | |
492 | idx = calc_index(expires, 6); | |
493 | } else if (LVL_DEPTH > 8 && delta < LVL_START(8)) { | |
494 | idx = calc_index(expires, 7); | |
495 | } else if ((long) delta < 0) { | |
ffdf0477 | 496 | idx = clk & LVL_MASK; |
1da177e4 | 497 | } else { |
500462a9 TG |
498 | /* |
499 | * Force expire obscene large timeouts to expire at the | |
500 | * capacity limit of the wheel. | |
1da177e4 | 501 | */ |
500462a9 TG |
502 | if (expires >= WHEEL_TIMEOUT_CUTOFF) |
503 | expires = WHEEL_TIMEOUT_MAX; | |
1bd04bf6 | 504 | |
500462a9 | 505 | idx = calc_index(expires, LVL_DEPTH - 1); |
1da177e4 | 506 | } |
ffdf0477 AMG |
507 | return idx; |
508 | } | |
1bd04bf6 | 509 | |
ffdf0477 AMG |
510 | /* |
511 | * Enqueue the timer into the hash bucket, mark it pending in | |
512 | * the bitmap and store the index in the timer flags. | |
513 | */ | |
514 | static void enqueue_timer(struct timer_base *base, struct timer_list *timer, | |
515 | unsigned int idx) | |
516 | { | |
517 | hlist_add_head(&timer->entry, base->vectors + idx); | |
500462a9 TG |
518 | __set_bit(idx, base->pending_map); |
519 | timer_set_idx(timer, idx); | |
1da177e4 LT |
520 | } |
521 | ||
ffdf0477 AMG |
522 | static void |
523 | __internal_add_timer(struct timer_base *base, struct timer_list *timer) | |
facbb4a7 | 524 | { |
ffdf0477 AMG |
525 | unsigned int idx; |
526 | ||
527 | idx = calc_wheel_index(timer->expires, base->clk); | |
528 | enqueue_timer(base, timer, idx); | |
529 | } | |
9f6d9baa | 530 | |
ffdf0477 AMG |
531 | static void |
532 | trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) | |
533 | { | |
a683f390 TG |
534 | if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->nohz_active) |
535 | return; | |
3bb475a3 | 536 | |
facbb4a7 | 537 | /* |
a683f390 TG |
538 | * TODO: This wants some optimizing similar to the code below, but we |
539 | * will do that when we switch from push to pull for deferrable timers. | |
facbb4a7 | 540 | */ |
a683f390 TG |
541 | if (timer->flags & TIMER_DEFERRABLE) { |
542 | if (tick_nohz_full_cpu(base->cpu)) | |
683be13a | 543 | wake_up_nohz_cpu(base->cpu); |
a683f390 | 544 | return; |
99d5f3aa | 545 | } |
9f6d9baa VK |
546 | |
547 | /* | |
a683f390 TG |
548 | * We might have to IPI the remote CPU if the base is idle and the |
549 | * timer is not deferrable. If the other CPU is on the way to idle | |
550 | * then it can't set base->is_idle as we hold the base lock: | |
9f6d9baa | 551 | */ |
a683f390 TG |
552 | if (!base->is_idle) |
553 | return; | |
554 | ||
555 | /* Check whether this is the new first expiring timer: */ | |
556 | if (time_after_eq(timer->expires, base->next_expiry)) | |
557 | return; | |
558 | ||
559 | /* | |
560 | * Set the next expiry time and kick the CPU so it can reevaluate the | |
561 | * wheel: | |
562 | */ | |
563 | base->next_expiry = timer->expires; | |
ffdf0477 AMG |
564 | wake_up_nohz_cpu(base->cpu); |
565 | } | |
566 | ||
567 | static void | |
568 | internal_add_timer(struct timer_base *base, struct timer_list *timer) | |
569 | { | |
570 | __internal_add_timer(base, timer); | |
571 | trigger_dyntick_cpu(base, timer); | |
facbb4a7 TG |
572 | } |
573 | ||
c6f3a97f TG |
574 | #ifdef CONFIG_DEBUG_OBJECTS_TIMERS |
575 | ||
576 | static struct debug_obj_descr timer_debug_descr; | |
577 | ||
99777288 SG |
578 | static void *timer_debug_hint(void *addr) |
579 | { | |
580 | return ((struct timer_list *) addr)->function; | |
581 | } | |
582 | ||
b9fdac7f DC |
583 | static bool timer_is_static_object(void *addr) |
584 | { | |
585 | struct timer_list *timer = addr; | |
586 | ||
587 | return (timer->entry.pprev == NULL && | |
588 | timer->entry.next == TIMER_ENTRY_STATIC); | |
589 | } | |
590 | ||
c6f3a97f TG |
591 | /* |
592 | * fixup_init is called when: | |
593 | * - an active object is initialized | |
55c888d6 | 594 | */ |
e3252464 | 595 | static bool timer_fixup_init(void *addr, enum debug_obj_state state) |
c6f3a97f TG |
596 | { |
597 | struct timer_list *timer = addr; | |
598 | ||
599 | switch (state) { | |
600 | case ODEBUG_STATE_ACTIVE: | |
601 | del_timer_sync(timer); | |
602 | debug_object_init(timer, &timer_debug_descr); | |
e3252464 | 603 | return true; |
c6f3a97f | 604 | default: |
e3252464 | 605 | return false; |
c6f3a97f TG |
606 | } |
607 | } | |
608 | ||
fb16b8cf SB |
609 | /* Stub timer callback for improperly used timers. */ |
610 | static void stub_timer(unsigned long data) | |
611 | { | |
612 | WARN_ON(1); | |
613 | } | |
614 | ||
c6f3a97f TG |
615 | /* |
616 | * fixup_activate is called when: | |
617 | * - an active object is activated | |
b9fdac7f | 618 | * - an unknown non-static object is activated |
c6f3a97f | 619 | */ |
e3252464 | 620 | static bool timer_fixup_activate(void *addr, enum debug_obj_state state) |
c6f3a97f TG |
621 | { |
622 | struct timer_list *timer = addr; | |
623 | ||
624 | switch (state) { | |
c6f3a97f | 625 | case ODEBUG_STATE_NOTAVAILABLE: |
b9fdac7f DC |
626 | setup_timer(timer, stub_timer, 0); |
627 | return true; | |
c6f3a97f TG |
628 | |
629 | case ODEBUG_STATE_ACTIVE: | |
630 | WARN_ON(1); | |
631 | ||
632 | default: | |
e3252464 | 633 | return false; |
c6f3a97f TG |
634 | } |
635 | } | |
636 | ||
637 | /* | |
638 | * fixup_free is called when: | |
639 | * - an active object is freed | |
640 | */ | |
e3252464 | 641 | static bool timer_fixup_free(void *addr, enum debug_obj_state state) |
c6f3a97f TG |
642 | { |
643 | struct timer_list *timer = addr; | |
644 | ||
645 | switch (state) { | |
646 | case ODEBUG_STATE_ACTIVE: | |
647 | del_timer_sync(timer); | |
648 | debug_object_free(timer, &timer_debug_descr); | |
e3252464 | 649 | return true; |
c6f3a97f | 650 | default: |
e3252464 | 651 | return false; |
c6f3a97f TG |
652 | } |
653 | } | |
654 | ||
dc4218bd CC |
655 | /* |
656 | * fixup_assert_init is called when: | |
657 | * - an untracked/uninit-ed object is found | |
658 | */ | |
e3252464 | 659 | static bool timer_fixup_assert_init(void *addr, enum debug_obj_state state) |
dc4218bd CC |
660 | { |
661 | struct timer_list *timer = addr; | |
662 | ||
663 | switch (state) { | |
664 | case ODEBUG_STATE_NOTAVAILABLE: | |
b9fdac7f DC |
665 | setup_timer(timer, stub_timer, 0); |
666 | return true; | |
dc4218bd | 667 | default: |
e3252464 | 668 | return false; |
dc4218bd CC |
669 | } |
670 | } | |
671 | ||
c6f3a97f | 672 | static struct debug_obj_descr timer_debug_descr = { |
dc4218bd CC |
673 | .name = "timer_list", |
674 | .debug_hint = timer_debug_hint, | |
b9fdac7f | 675 | .is_static_object = timer_is_static_object, |
dc4218bd CC |
676 | .fixup_init = timer_fixup_init, |
677 | .fixup_activate = timer_fixup_activate, | |
678 | .fixup_free = timer_fixup_free, | |
679 | .fixup_assert_init = timer_fixup_assert_init, | |
c6f3a97f TG |
680 | }; |
681 | ||
682 | static inline void debug_timer_init(struct timer_list *timer) | |
683 | { | |
684 | debug_object_init(timer, &timer_debug_descr); | |
685 | } | |
686 | ||
687 | static inline void debug_timer_activate(struct timer_list *timer) | |
688 | { | |
689 | debug_object_activate(timer, &timer_debug_descr); | |
690 | } | |
691 | ||
692 | static inline void debug_timer_deactivate(struct timer_list *timer) | |
693 | { | |
694 | debug_object_deactivate(timer, &timer_debug_descr); | |
695 | } | |
696 | ||
697 | static inline void debug_timer_free(struct timer_list *timer) | |
698 | { | |
699 | debug_object_free(timer, &timer_debug_descr); | |
700 | } | |
701 | ||
dc4218bd CC |
702 | static inline void debug_timer_assert_init(struct timer_list *timer) |
703 | { | |
704 | debug_object_assert_init(timer, &timer_debug_descr); | |
705 | } | |
706 | ||
fc683995 TH |
707 | static void do_init_timer(struct timer_list *timer, unsigned int flags, |
708 | const char *name, struct lock_class_key *key); | |
c6f3a97f | 709 | |
fc683995 TH |
710 | void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags, |
711 | const char *name, struct lock_class_key *key) | |
c6f3a97f TG |
712 | { |
713 | debug_object_init_on_stack(timer, &timer_debug_descr); | |
fc683995 | 714 | do_init_timer(timer, flags, name, key); |
c6f3a97f | 715 | } |
6f2b9b9a | 716 | EXPORT_SYMBOL_GPL(init_timer_on_stack_key); |
c6f3a97f TG |
717 | |
718 | void destroy_timer_on_stack(struct timer_list *timer) | |
719 | { | |
720 | debug_object_free(timer, &timer_debug_descr); | |
721 | } | |
722 | EXPORT_SYMBOL_GPL(destroy_timer_on_stack); | |
723 | ||
724 | #else | |
725 | static inline void debug_timer_init(struct timer_list *timer) { } | |
726 | static inline void debug_timer_activate(struct timer_list *timer) { } | |
727 | static inline void debug_timer_deactivate(struct timer_list *timer) { } | |
dc4218bd | 728 | static inline void debug_timer_assert_init(struct timer_list *timer) { } |
c6f3a97f TG |
729 | #endif |
730 | ||
2b022e3d XG |
731 | static inline void debug_init(struct timer_list *timer) |
732 | { | |
733 | debug_timer_init(timer); | |
734 | trace_timer_init(timer); | |
735 | } | |
736 | ||
737 | static inline void | |
738 | debug_activate(struct timer_list *timer, unsigned long expires) | |
739 | { | |
740 | debug_timer_activate(timer); | |
0eeda71b | 741 | trace_timer_start(timer, expires, timer->flags); |
2b022e3d XG |
742 | } |
743 | ||
744 | static inline void debug_deactivate(struct timer_list *timer) | |
745 | { | |
746 | debug_timer_deactivate(timer); | |
747 | trace_timer_cancel(timer); | |
748 | } | |
749 | ||
dc4218bd CC |
750 | static inline void debug_assert_init(struct timer_list *timer) |
751 | { | |
752 | debug_timer_assert_init(timer); | |
753 | } | |
754 | ||
fc683995 TH |
755 | static void do_init_timer(struct timer_list *timer, unsigned int flags, |
756 | const char *name, struct lock_class_key *key) | |
55c888d6 | 757 | { |
1dabbcec | 758 | timer->entry.pprev = NULL; |
0eeda71b | 759 | timer->flags = flags | raw_smp_processor_id(); |
6f2b9b9a | 760 | lockdep_init_map(&timer->lockdep_map, name, key, 0); |
55c888d6 | 761 | } |
c6f3a97f TG |
762 | |
763 | /** | |
633fe795 | 764 | * init_timer_key - initialize a timer |
c6f3a97f | 765 | * @timer: the timer to be initialized |
fc683995 | 766 | * @flags: timer flags |
633fe795 RD |
767 | * @name: name of the timer |
768 | * @key: lockdep class key of the fake lock used for tracking timer | |
769 | * sync lock dependencies | |
c6f3a97f | 770 | * |
633fe795 | 771 | * init_timer_key() must be done to a timer prior calling *any* of the |
c6f3a97f TG |
772 | * other timer functions. |
773 | */ | |
fc683995 TH |
774 | void init_timer_key(struct timer_list *timer, unsigned int flags, |
775 | const char *name, struct lock_class_key *key) | |
c6f3a97f | 776 | { |
2b022e3d | 777 | debug_init(timer); |
fc683995 | 778 | do_init_timer(timer, flags, name, key); |
c6f3a97f | 779 | } |
6f2b9b9a | 780 | EXPORT_SYMBOL(init_timer_key); |
55c888d6 | 781 | |
ec44bc7a | 782 | static inline void detach_timer(struct timer_list *timer, bool clear_pending) |
55c888d6 | 783 | { |
1dabbcec | 784 | struct hlist_node *entry = &timer->entry; |
55c888d6 | 785 | |
2b022e3d | 786 | debug_deactivate(timer); |
c6f3a97f | 787 | |
1dabbcec | 788 | __hlist_del(entry); |
55c888d6 | 789 | if (clear_pending) |
1dabbcec TG |
790 | entry->pprev = NULL; |
791 | entry->next = LIST_POISON2; | |
55c888d6 ON |
792 | } |
793 | ||
494af3ed | 794 | static int detach_if_pending(struct timer_list *timer, struct timer_base *base, |
ec44bc7a TG |
795 | bool clear_pending) |
796 | { | |
500462a9 TG |
797 | unsigned idx = timer_get_idx(timer); |
798 | ||
ec44bc7a TG |
799 | if (!timer_pending(timer)) |
800 | return 0; | |
801 | ||
500462a9 TG |
802 | if (hlist_is_singular_node(&timer->entry, base->vectors + idx)) |
803 | __clear_bit(idx, base->pending_map); | |
804 | ||
ec44bc7a | 805 | detach_timer(timer, clear_pending); |
ec44bc7a TG |
806 | return 1; |
807 | } | |
808 | ||
500462a9 TG |
809 | static inline struct timer_base *get_timer_cpu_base(u32 tflags, u32 cpu) |
810 | { | |
811 | struct timer_base *base = per_cpu_ptr(&timer_bases[BASE_STD], cpu); | |
812 | ||
813 | /* | |
814 | * If the timer is deferrable and nohz is active then we need to use | |
815 | * the deferrable base. | |
816 | */ | |
817 | if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && base->nohz_active && | |
818 | (tflags & TIMER_DEFERRABLE)) | |
819 | base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu); | |
820 | return base; | |
821 | } | |
822 | ||
823 | static inline struct timer_base *get_timer_this_cpu_base(u32 tflags) | |
824 | { | |
825 | struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); | |
826 | ||
827 | /* | |
828 | * If the timer is deferrable and nohz is active then we need to use | |
829 | * the deferrable base. | |
830 | */ | |
831 | if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && base->nohz_active && | |
832 | (tflags & TIMER_DEFERRABLE)) | |
833 | base = this_cpu_ptr(&timer_bases[BASE_DEF]); | |
834 | return base; | |
835 | } | |
836 | ||
837 | static inline struct timer_base *get_timer_base(u32 tflags) | |
838 | { | |
839 | return get_timer_cpu_base(tflags, tflags & TIMER_CPUMASK); | |
840 | } | |
841 | ||
a683f390 TG |
842 | #ifdef CONFIG_NO_HZ_COMMON |
843 | static inline struct timer_base * | |
6bad6bcc | 844 | get_target_base(struct timer_base *base, unsigned tflags) |
500462a9 | 845 | { |
a683f390 | 846 | #ifdef CONFIG_SMP |
500462a9 TG |
847 | if ((tflags & TIMER_PINNED) || !base->migration_enabled) |
848 | return get_timer_this_cpu_base(tflags); | |
849 | return get_timer_cpu_base(tflags, get_nohz_timer_target()); | |
850 | #else | |
851 | return get_timer_this_cpu_base(tflags); | |
852 | #endif | |
853 | } | |
854 | ||
a683f390 TG |
855 | static inline void forward_timer_base(struct timer_base *base) |
856 | { | |
6bad6bcc TG |
857 | unsigned long jnow = READ_ONCE(jiffies); |
858 | ||
a683f390 TG |
859 | /* |
860 | * We only forward the base when it's idle and we have a delta between | |
861 | * base clock and jiffies. | |
862 | */ | |
6bad6bcc | 863 | if (!base->is_idle || (long) (jnow - base->clk) < 2) |
a683f390 TG |
864 | return; |
865 | ||
866 | /* | |
867 | * If the next expiry value is > jiffies, then we fast forward to | |
868 | * jiffies otherwise we forward to the next expiry value. | |
869 | */ | |
6bad6bcc TG |
870 | if (time_after(base->next_expiry, jnow)) |
871 | base->clk = jnow; | |
a683f390 TG |
872 | else |
873 | base->clk = base->next_expiry; | |
874 | } | |
875 | #else | |
876 | static inline struct timer_base * | |
6bad6bcc | 877 | get_target_base(struct timer_base *base, unsigned tflags) |
a683f390 TG |
878 | { |
879 | return get_timer_this_cpu_base(tflags); | |
880 | } | |
881 | ||
882 | static inline void forward_timer_base(struct timer_base *base) { } | |
883 | #endif | |
884 | ||
a683f390 | 885 | |
55c888d6 | 886 | /* |
500462a9 TG |
887 | * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means |
888 | * that all timers which are tied to this base are locked, and the base itself | |
889 | * is locked too. | |
55c888d6 ON |
890 | * |
891 | * So __run_timers/migrate_timers can safely modify all timers which could | |
500462a9 | 892 | * be found in the base->vectors array. |
55c888d6 | 893 | * |
500462a9 TG |
894 | * When a timer is migrating then the TIMER_MIGRATING flag is set and we need |
895 | * to wait until the migration is done. | |
55c888d6 | 896 | */ |
494af3ed | 897 | static struct timer_base *lock_timer_base(struct timer_list *timer, |
500462a9 | 898 | unsigned long *flags) |
89e7e374 | 899 | __acquires(timer->base->lock) |
55c888d6 | 900 | { |
55c888d6 | 901 | for (;;) { |
494af3ed | 902 | struct timer_base *base; |
b831275a TG |
903 | u32 tf; |
904 | ||
905 | /* | |
906 | * We need to use READ_ONCE() here, otherwise the compiler | |
907 | * might re-read @tf between the check for TIMER_MIGRATING | |
908 | * and spin_lock(). | |
909 | */ | |
910 | tf = READ_ONCE(timer->flags); | |
0eeda71b TG |
911 | |
912 | if (!(tf & TIMER_MIGRATING)) { | |
500462a9 | 913 | base = get_timer_base(tf); |
55c888d6 | 914 | spin_lock_irqsave(&base->lock, *flags); |
0eeda71b | 915 | if (timer->flags == tf) |
55c888d6 | 916 | return base; |
55c888d6 ON |
917 | spin_unlock_irqrestore(&base->lock, *flags); |
918 | } | |
919 | cpu_relax(); | |
920 | } | |
921 | } | |
922 | ||
74019224 | 923 | static inline int |
177ec0a0 | 924 | __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only) |
1da177e4 | 925 | { |
494af3ed | 926 | struct timer_base *base, *new_base; |
f00c0afd AMG |
927 | unsigned int idx = UINT_MAX; |
928 | unsigned long clk = 0, flags; | |
bc7a34b8 | 929 | int ret = 0; |
1da177e4 | 930 | |
4da9152a TG |
931 | BUG_ON(!timer->function); |
932 | ||
500462a9 | 933 | /* |
f00c0afd AMG |
934 | * This is a common optimization triggered by the networking code - if |
935 | * the timer is re-modified to have the same timeout or ends up in the | |
936 | * same array bucket then just return: | |
500462a9 TG |
937 | */ |
938 | if (timer_pending(timer)) { | |
939 | if (timer->expires == expires) | |
940 | return 1; | |
4da9152a | 941 | |
f00c0afd | 942 | /* |
4da9152a TG |
943 | * We lock timer base and calculate the bucket index right |
944 | * here. If the timer ends up in the same bucket, then we | |
945 | * just update the expiry time and avoid the whole | |
946 | * dequeue/enqueue dance. | |
f00c0afd | 947 | */ |
4da9152a | 948 | base = lock_timer_base(timer, &flags); |
f00c0afd | 949 | |
4da9152a | 950 | clk = base->clk; |
f00c0afd AMG |
951 | idx = calc_wheel_index(expires, clk); |
952 | ||
953 | /* | |
954 | * Retrieve and compare the array index of the pending | |
955 | * timer. If it matches set the expiry to the new value so a | |
956 | * subsequent call will exit in the expires check above. | |
957 | */ | |
958 | if (idx == timer_get_idx(timer)) { | |
959 | timer->expires = expires; | |
4da9152a TG |
960 | ret = 1; |
961 | goto out_unlock; | |
f00c0afd | 962 | } |
4da9152a TG |
963 | } else { |
964 | base = lock_timer_base(timer, &flags); | |
500462a9 TG |
965 | } |
966 | ||
ec44bc7a TG |
967 | ret = detach_if_pending(timer, base, false); |
968 | if (!ret && pending_only) | |
969 | goto out_unlock; | |
55c888d6 | 970 | |
2b022e3d | 971 | debug_activate(timer, expires); |
c6f3a97f | 972 | |
500462a9 | 973 | new_base = get_target_base(base, timer->flags); |
eea08f32 | 974 | |
3691c519 | 975 | if (base != new_base) { |
1da177e4 | 976 | /* |
500462a9 | 977 | * We are trying to schedule the timer on the new base. |
55c888d6 ON |
978 | * However we can't change timer's base while it is running, |
979 | * otherwise del_timer_sync() can't detect that the timer's | |
500462a9 TG |
980 | * handler yet has not finished. This also guarantees that the |
981 | * timer is serialized wrt itself. | |
1da177e4 | 982 | */ |
a2c348fe | 983 | if (likely(base->running_timer != timer)) { |
55c888d6 | 984 | /* See the comment in lock_timer_base() */ |
0eeda71b TG |
985 | timer->flags |= TIMER_MIGRATING; |
986 | ||
55c888d6 | 987 | spin_unlock(&base->lock); |
a2c348fe ON |
988 | base = new_base; |
989 | spin_lock(&base->lock); | |
d0023a14 ED |
990 | WRITE_ONCE(timer->flags, |
991 | (timer->flags & ~TIMER_BASEMASK) | base->cpu); | |
1da177e4 LT |
992 | } |
993 | } | |
994 | ||
6bad6bcc TG |
995 | /* Try to forward a stale timer base clock */ |
996 | forward_timer_base(base); | |
997 | ||
1da177e4 | 998 | timer->expires = expires; |
f00c0afd AMG |
999 | /* |
1000 | * If 'idx' was calculated above and the base time did not advance | |
4da9152a TG |
1001 | * between calculating 'idx' and possibly switching the base, only |
1002 | * enqueue_timer() and trigger_dyntick_cpu() is required. Otherwise | |
1003 | * we need to (re)calculate the wheel index via | |
1004 | * internal_add_timer(). | |
f00c0afd AMG |
1005 | */ |
1006 | if (idx != UINT_MAX && clk == base->clk) { | |
1007 | enqueue_timer(base, timer, idx); | |
1008 | trigger_dyntick_cpu(base, timer); | |
1009 | } else { | |
1010 | internal_add_timer(base, timer); | |
1011 | } | |
74019224 IM |
1012 | |
1013 | out_unlock: | |
a2c348fe | 1014 | spin_unlock_irqrestore(&base->lock, flags); |
1da177e4 LT |
1015 | |
1016 | return ret; | |
1017 | } | |
1018 | ||
2aae4a10 | 1019 | /** |
74019224 IM |
1020 | * mod_timer_pending - modify a pending timer's timeout |
1021 | * @timer: the pending timer to be modified | |
1022 | * @expires: new timeout in jiffies | |
1da177e4 | 1023 | * |
74019224 IM |
1024 | * mod_timer_pending() is the same for pending timers as mod_timer(), |
1025 | * but will not re-activate and modify already deleted timers. | |
1026 | * | |
1027 | * It is useful for unserialized use of timers. | |
1da177e4 | 1028 | */ |
74019224 | 1029 | int mod_timer_pending(struct timer_list *timer, unsigned long expires) |
1da177e4 | 1030 | { |
177ec0a0 | 1031 | return __mod_timer(timer, expires, true); |
1da177e4 | 1032 | } |
74019224 | 1033 | EXPORT_SYMBOL(mod_timer_pending); |
1da177e4 | 1034 | |
2aae4a10 | 1035 | /** |
1da177e4 LT |
1036 | * mod_timer - modify a timer's timeout |
1037 | * @timer: the timer to be modified | |
2aae4a10 | 1038 | * @expires: new timeout in jiffies |
1da177e4 | 1039 | * |
72fd4a35 | 1040 | * mod_timer() is a more efficient way to update the expire field of an |
1da177e4 LT |
1041 | * active timer (if the timer is inactive it will be activated) |
1042 | * | |
1043 | * mod_timer(timer, expires) is equivalent to: | |
1044 | * | |
1045 | * del_timer(timer); timer->expires = expires; add_timer(timer); | |
1046 | * | |
1047 | * Note that if there are multiple unserialized concurrent users of the | |
1048 | * same timer, then mod_timer() is the only safe way to modify the timeout, | |
1049 | * since add_timer() cannot modify an already running timer. | |
1050 | * | |
1051 | * The function returns whether it has modified a pending timer or not. | |
1052 | * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an | |
1053 | * active timer returns 1.) | |
1054 | */ | |
1055 | int mod_timer(struct timer_list *timer, unsigned long expires) | |
1056 | { | |
177ec0a0 | 1057 | return __mod_timer(timer, expires, false); |
1da177e4 | 1058 | } |
1da177e4 LT |
1059 | EXPORT_SYMBOL(mod_timer); |
1060 | ||
74019224 IM |
1061 | /** |
1062 | * add_timer - start a timer | |
1063 | * @timer: the timer to be added | |
1064 | * | |
1065 | * The kernel will do a ->function(->data) callback from the | |
1066 | * timer interrupt at the ->expires point in the future. The | |
1067 | * current time is 'jiffies'. | |
1068 | * | |
1069 | * The timer's ->expires, ->function (and if the handler uses it, ->data) | |
1070 | * fields must be set prior calling this function. | |
1071 | * | |
1072 | * Timers with an ->expires field in the past will be executed in the next | |
1073 | * timer tick. | |
1074 | */ | |
1075 | void add_timer(struct timer_list *timer) | |
1076 | { | |
1077 | BUG_ON(timer_pending(timer)); | |
1078 | mod_timer(timer, timer->expires); | |
1079 | } | |
1080 | EXPORT_SYMBOL(add_timer); | |
1081 | ||
1082 | /** | |
1083 | * add_timer_on - start a timer on a particular CPU | |
1084 | * @timer: the timer to be added | |
1085 | * @cpu: the CPU to start it on | |
1086 | * | |
1087 | * This is not very scalable on SMP. Double adds are not possible. | |
1088 | */ | |
1089 | void add_timer_on(struct timer_list *timer, int cpu) | |
1090 | { | |
500462a9 | 1091 | struct timer_base *new_base, *base; |
74019224 IM |
1092 | unsigned long flags; |
1093 | ||
74019224 | 1094 | BUG_ON(timer_pending(timer) || !timer->function); |
22b886dd | 1095 | |
500462a9 TG |
1096 | new_base = get_timer_cpu_base(timer->flags, cpu); |
1097 | ||
22b886dd TH |
1098 | /* |
1099 | * If @timer was on a different CPU, it should be migrated with the | |
1100 | * old base locked to prevent other operations proceeding with the | |
1101 | * wrong base locked. See lock_timer_base(). | |
1102 | */ | |
1103 | base = lock_timer_base(timer, &flags); | |
1104 | if (base != new_base) { | |
1105 | timer->flags |= TIMER_MIGRATING; | |
1106 | ||
1107 | spin_unlock(&base->lock); | |
1108 | base = new_base; | |
1109 | spin_lock(&base->lock); | |
1110 | WRITE_ONCE(timer->flags, | |
1111 | (timer->flags & ~TIMER_BASEMASK) | cpu); | |
1112 | } | |
1113 | ||
2b022e3d | 1114 | debug_activate(timer, timer->expires); |
74019224 | 1115 | internal_add_timer(base, timer); |
74019224 IM |
1116 | spin_unlock_irqrestore(&base->lock, flags); |
1117 | } | |
a9862e05 | 1118 | EXPORT_SYMBOL_GPL(add_timer_on); |
74019224 | 1119 | |
2aae4a10 | 1120 | /** |
1da177e4 LT |
1121 | * del_timer - deactive a timer. |
1122 | * @timer: the timer to be deactivated | |
1123 | * | |
1124 | * del_timer() deactivates a timer - this works on both active and inactive | |
1125 | * timers. | |
1126 | * | |
1127 | * The function returns whether it has deactivated a pending timer or not. | |
1128 | * (ie. del_timer() of an inactive timer returns 0, del_timer() of an | |
1129 | * active timer returns 1.) | |
1130 | */ | |
1131 | int del_timer(struct timer_list *timer) | |
1132 | { | |
494af3ed | 1133 | struct timer_base *base; |
1da177e4 | 1134 | unsigned long flags; |
55c888d6 | 1135 | int ret = 0; |
1da177e4 | 1136 | |
dc4218bd CC |
1137 | debug_assert_init(timer); |
1138 | ||
55c888d6 ON |
1139 | if (timer_pending(timer)) { |
1140 | base = lock_timer_base(timer, &flags); | |
ec44bc7a | 1141 | ret = detach_if_pending(timer, base, true); |
1da177e4 | 1142 | spin_unlock_irqrestore(&base->lock, flags); |
1da177e4 | 1143 | } |
1da177e4 | 1144 | |
55c888d6 | 1145 | return ret; |
1da177e4 | 1146 | } |
1da177e4 LT |
1147 | EXPORT_SYMBOL(del_timer); |
1148 | ||
2aae4a10 REB |
1149 | /** |
1150 | * try_to_del_timer_sync - Try to deactivate a timer | |
1151 | * @timer: timer do del | |
1152 | * | |
fd450b73 ON |
1153 | * This function tries to deactivate a timer. Upon successful (ret >= 0) |
1154 | * exit the timer is not queued and the handler is not running on any CPU. | |
fd450b73 ON |
1155 | */ |
1156 | int try_to_del_timer_sync(struct timer_list *timer) | |
1157 | { | |
494af3ed | 1158 | struct timer_base *base; |
fd450b73 ON |
1159 | unsigned long flags; |
1160 | int ret = -1; | |
1161 | ||
dc4218bd CC |
1162 | debug_assert_init(timer); |
1163 | ||
fd450b73 ON |
1164 | base = lock_timer_base(timer, &flags); |
1165 | ||
dfb4357d | 1166 | if (base->running_timer != timer) |
ec44bc7a | 1167 | ret = detach_if_pending(timer, base, true); |
dfb4357d | 1168 | |
fd450b73 ON |
1169 | spin_unlock_irqrestore(&base->lock, flags); |
1170 | ||
1171 | return ret; | |
1172 | } | |
e19dff1f DH |
1173 | EXPORT_SYMBOL(try_to_del_timer_sync); |
1174 | ||
6f1bc451 | 1175 | #ifdef CONFIG_SMP |
2aae4a10 | 1176 | /** |
1da177e4 LT |
1177 | * del_timer_sync - deactivate a timer and wait for the handler to finish. |
1178 | * @timer: the timer to be deactivated | |
1179 | * | |
1180 | * This function only differs from del_timer() on SMP: besides deactivating | |
1181 | * the timer it also makes sure the handler has finished executing on other | |
1182 | * CPUs. | |
1183 | * | |
72fd4a35 | 1184 | * Synchronization rules: Callers must prevent restarting of the timer, |
1da177e4 | 1185 | * otherwise this function is meaningless. It must not be called from |
c5f66e99 TH |
1186 | * interrupt contexts unless the timer is an irqsafe one. The caller must |
1187 | * not hold locks which would prevent completion of the timer's | |
1188 | * handler. The timer's handler must not call add_timer_on(). Upon exit the | |
1189 | * timer is not queued and the handler is not running on any CPU. | |
1da177e4 | 1190 | * |
c5f66e99 TH |
1191 | * Note: For !irqsafe timers, you must not hold locks that are held in |
1192 | * interrupt context while calling this function. Even if the lock has | |
1193 | * nothing to do with the timer in question. Here's why: | |
48228f7b SR |
1194 | * |
1195 | * CPU0 CPU1 | |
1196 | * ---- ---- | |
1197 | * <SOFTIRQ> | |
1198 | * call_timer_fn(); | |
1199 | * base->running_timer = mytimer; | |
1200 | * spin_lock_irq(somelock); | |
1201 | * <IRQ> | |
1202 | * spin_lock(somelock); | |
1203 | * del_timer_sync(mytimer); | |
1204 | * while (base->running_timer == mytimer); | |
1205 | * | |
1206 | * Now del_timer_sync() will never return and never release somelock. | |
1207 | * The interrupt on the other CPU is waiting to grab somelock but | |
1208 | * it has interrupted the softirq that CPU0 is waiting to finish. | |
1209 | * | |
1da177e4 | 1210 | * The function returns whether it has deactivated a pending timer or not. |
1da177e4 LT |
1211 | */ |
1212 | int del_timer_sync(struct timer_list *timer) | |
1213 | { | |
6f2b9b9a | 1214 | #ifdef CONFIG_LOCKDEP |
f266a511 PZ |
1215 | unsigned long flags; |
1216 | ||
48228f7b SR |
1217 | /* |
1218 | * If lockdep gives a backtrace here, please reference | |
1219 | * the synchronization rules above. | |
1220 | */ | |
7ff20792 | 1221 | local_irq_save(flags); |
6f2b9b9a JB |
1222 | lock_map_acquire(&timer->lockdep_map); |
1223 | lock_map_release(&timer->lockdep_map); | |
7ff20792 | 1224 | local_irq_restore(flags); |
6f2b9b9a | 1225 | #endif |
466bd303 YZ |
1226 | /* |
1227 | * don't use it in hardirq context, because it | |
1228 | * could lead to deadlock. | |
1229 | */ | |
0eeda71b | 1230 | WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE)); |
fd450b73 ON |
1231 | for (;;) { |
1232 | int ret = try_to_del_timer_sync(timer); | |
1233 | if (ret >= 0) | |
1234 | return ret; | |
a0009652 | 1235 | cpu_relax(); |
fd450b73 | 1236 | } |
1da177e4 | 1237 | } |
55c888d6 | 1238 | EXPORT_SYMBOL(del_timer_sync); |
1da177e4 LT |
1239 | #endif |
1240 | ||
576da126 TG |
1241 | static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long), |
1242 | unsigned long data) | |
1243 | { | |
4a2b4b22 | 1244 | int count = preempt_count(); |
576da126 TG |
1245 | |
1246 | #ifdef CONFIG_LOCKDEP | |
1247 | /* | |
1248 | * It is permissible to free the timer from inside the | |
1249 | * function that is called from it, this we need to take into | |
1250 | * account for lockdep too. To avoid bogus "held lock freed" | |
1251 | * warnings as well as problems when looking into | |
1252 | * timer->lockdep_map, make a copy and use that here. | |
1253 | */ | |
4d82a1de PZ |
1254 | struct lockdep_map lockdep_map; |
1255 | ||
1256 | lockdep_copy_map(&lockdep_map, &timer->lockdep_map); | |
576da126 TG |
1257 | #endif |
1258 | /* | |
1259 | * Couple the lock chain with the lock chain at | |
1260 | * del_timer_sync() by acquiring the lock_map around the fn() | |
1261 | * call here and in del_timer_sync(). | |
1262 | */ | |
1263 | lock_map_acquire(&lockdep_map); | |
1264 | ||
1265 | trace_timer_expire_entry(timer); | |
1266 | fn(data); | |
1267 | trace_timer_expire_exit(timer); | |
1268 | ||
1269 | lock_map_release(&lockdep_map); | |
1270 | ||
4a2b4b22 | 1271 | if (count != preempt_count()) { |
802702e0 | 1272 | WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n", |
4a2b4b22 | 1273 | fn, count, preempt_count()); |
802702e0 TG |
1274 | /* |
1275 | * Restore the preempt count. That gives us a decent | |
1276 | * chance to survive and extract information. If the | |
1277 | * callback kept a lock held, bad luck, but not worse | |
1278 | * than the BUG() we had. | |
1279 | */ | |
4a2b4b22 | 1280 | preempt_count_set(count); |
576da126 TG |
1281 | } |
1282 | } | |
1283 | ||
500462a9 | 1284 | static void expire_timers(struct timer_base *base, struct hlist_head *head) |
1da177e4 | 1285 | { |
500462a9 TG |
1286 | while (!hlist_empty(head)) { |
1287 | struct timer_list *timer; | |
1288 | void (*fn)(unsigned long); | |
1289 | unsigned long data; | |
1da177e4 | 1290 | |
500462a9 | 1291 | timer = hlist_entry(head->first, struct timer_list, entry); |
3bb475a3 | 1292 | |
500462a9 TG |
1293 | base->running_timer = timer; |
1294 | detach_timer(timer, true); | |
3bb475a3 | 1295 | |
500462a9 TG |
1296 | fn = timer->function; |
1297 | data = timer->data; | |
1298 | ||
1299 | if (timer->flags & TIMER_IRQSAFE) { | |
1300 | spin_unlock(&base->lock); | |
1301 | call_timer_fn(timer, fn, data); | |
1302 | spin_lock(&base->lock); | |
1303 | } else { | |
1304 | spin_unlock_irq(&base->lock); | |
1305 | call_timer_fn(timer, fn, data); | |
1306 | spin_lock_irq(&base->lock); | |
3bb475a3 | 1307 | } |
500462a9 TG |
1308 | } |
1309 | } | |
3bb475a3 | 1310 | |
23696838 AMG |
1311 | static int __collect_expired_timers(struct timer_base *base, |
1312 | struct hlist_head *heads) | |
500462a9 TG |
1313 | { |
1314 | unsigned long clk = base->clk; | |
1315 | struct hlist_head *vec; | |
1316 | int i, levels = 0; | |
1317 | unsigned int idx; | |
626ab0e6 | 1318 | |
500462a9 TG |
1319 | for (i = 0; i < LVL_DEPTH; i++) { |
1320 | idx = (clk & LVL_MASK) + i * LVL_SIZE; | |
1321 | ||
1322 | if (__test_and_clear_bit(idx, base->pending_map)) { | |
1323 | vec = base->vectors + idx; | |
1324 | hlist_move_list(vec, heads++); | |
1325 | levels++; | |
1da177e4 | 1326 | } |
500462a9 TG |
1327 | /* Is it time to look at the next level? */ |
1328 | if (clk & LVL_CLK_MASK) | |
1329 | break; | |
1330 | /* Shift clock for the next level granularity */ | |
1331 | clk >>= LVL_CLK_SHIFT; | |
1da177e4 | 1332 | } |
500462a9 | 1333 | return levels; |
1da177e4 LT |
1334 | } |
1335 | ||
3451d024 | 1336 | #ifdef CONFIG_NO_HZ_COMMON |
1da177e4 | 1337 | /* |
23696838 AMG |
1338 | * Find the next pending bucket of a level. Search from level start (@offset) |
1339 | * + @clk upwards and if nothing there, search from start of the level | |
1340 | * (@offset) up to @offset + clk. | |
1da177e4 | 1341 | */ |
500462a9 TG |
1342 | static int next_pending_bucket(struct timer_base *base, unsigned offset, |
1343 | unsigned clk) | |
1344 | { | |
1345 | unsigned pos, start = offset + clk; | |
1346 | unsigned end = offset + LVL_SIZE; | |
1347 | ||
1348 | pos = find_next_bit(base->pending_map, end, start); | |
1349 | if (pos < end) | |
1350 | return pos - start; | |
1351 | ||
1352 | pos = find_next_bit(base->pending_map, start, offset); | |
1353 | return pos < start ? pos + LVL_SIZE - start : -1; | |
1354 | } | |
1355 | ||
1356 | /* | |
23696838 AMG |
1357 | * Search the first expiring timer in the various clock levels. Caller must |
1358 | * hold base->lock. | |
1da177e4 | 1359 | */ |
494af3ed | 1360 | static unsigned long __next_timer_interrupt(struct timer_base *base) |
1da177e4 | 1361 | { |
500462a9 TG |
1362 | unsigned long clk, next, adj; |
1363 | unsigned lvl, offset = 0; | |
1364 | ||
500462a9 TG |
1365 | next = base->clk + NEXT_TIMER_MAX_DELTA; |
1366 | clk = base->clk; | |
1367 | for (lvl = 0; lvl < LVL_DEPTH; lvl++, offset += LVL_SIZE) { | |
1368 | int pos = next_pending_bucket(base, offset, clk & LVL_MASK); | |
1369 | ||
1370 | if (pos >= 0) { | |
1371 | unsigned long tmp = clk + (unsigned long) pos; | |
1372 | ||
1373 | tmp <<= LVL_SHIFT(lvl); | |
1374 | if (time_before(tmp, next)) | |
1375 | next = tmp; | |
1da177e4 | 1376 | } |
500462a9 TG |
1377 | /* |
1378 | * Clock for the next level. If the current level clock lower | |
1379 | * bits are zero, we look at the next level as is. If not we | |
1380 | * need to advance it by one because that's going to be the | |
1381 | * next expiring bucket in that level. base->clk is the next | |
1382 | * expiring jiffie. So in case of: | |
1383 | * | |
1384 | * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 | |
1385 | * 0 0 0 0 0 0 | |
1386 | * | |
1387 | * we have to look at all levels @index 0. With | |
1388 | * | |
1389 | * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 | |
1390 | * 0 0 0 0 0 2 | |
1391 | * | |
1392 | * LVL0 has the next expiring bucket @index 2. The upper | |
1393 | * levels have the next expiring bucket @index 1. | |
1394 | * | |
1395 | * In case that the propagation wraps the next level the same | |
1396 | * rules apply: | |
1397 | * | |
1398 | * LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 | |
1399 | * 0 0 0 0 F 2 | |
1400 | * | |
1401 | * So after looking at LVL0 we get: | |
1402 | * | |
1403 | * LVL5 LVL4 LVL3 LVL2 LVL1 | |
1404 | * 0 0 0 1 0 | |
1405 | * | |
1406 | * So no propagation from LVL1 to LVL2 because that happened | |
1407 | * with the add already, but then we need to propagate further | |
1408 | * from LVL2 to LVL3. | |
1409 | * | |
1410 | * So the simple check whether the lower bits of the current | |
1411 | * level are 0 or not is sufficient for all cases. | |
1412 | */ | |
1413 | adj = clk & LVL_CLK_MASK ? 1 : 0; | |
1414 | clk >>= LVL_CLK_SHIFT; | |
1415 | clk += adj; | |
1da177e4 | 1416 | } |
500462a9 | 1417 | return next; |
1cfd6849 | 1418 | } |
69239749 | 1419 | |
1cfd6849 TG |
1420 | /* |
1421 | * Check, if the next hrtimer event is before the next timer wheel | |
1422 | * event: | |
1423 | */ | |
c1ad348b | 1424 | static u64 cmp_next_hrtimer_event(u64 basem, u64 expires) |
1cfd6849 | 1425 | { |
c1ad348b | 1426 | u64 nextevt = hrtimer_get_next_event(); |
0662b713 | 1427 | |
9501b6cf | 1428 | /* |
c1ad348b TG |
1429 | * If high resolution timers are enabled |
1430 | * hrtimer_get_next_event() returns KTIME_MAX. | |
9501b6cf | 1431 | */ |
c1ad348b TG |
1432 | if (expires <= nextevt) |
1433 | return expires; | |
eaad084b TG |
1434 | |
1435 | /* | |
c1ad348b TG |
1436 | * If the next timer is already expired, return the tick base |
1437 | * time so the tick is fired immediately. | |
eaad084b | 1438 | */ |
c1ad348b TG |
1439 | if (nextevt <= basem) |
1440 | return basem; | |
eaad084b | 1441 | |
9501b6cf | 1442 | /* |
c1ad348b TG |
1443 | * Round up to the next jiffie. High resolution timers are |
1444 | * off, so the hrtimers are expired in the tick and we need to | |
1445 | * make sure that this tick really expires the timer to avoid | |
1446 | * a ping pong of the nohz stop code. | |
1447 | * | |
1448 | * Use DIV_ROUND_UP_ULL to prevent gcc calling __divdi3 | |
9501b6cf | 1449 | */ |
c1ad348b | 1450 | return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC; |
1da177e4 | 1451 | } |
1cfd6849 TG |
1452 | |
1453 | /** | |
c1ad348b TG |
1454 | * get_next_timer_interrupt - return the time (clock mono) of the next timer |
1455 | * @basej: base time jiffies | |
1456 | * @basem: base time clock monotonic | |
1457 | * | |
1458 | * Returns the tick aligned clock monotonic time of the next pending | |
1459 | * timer or KTIME_MAX if no timer is pending. | |
1cfd6849 | 1460 | */ |
c1ad348b | 1461 | u64 get_next_timer_interrupt(unsigned long basej, u64 basem) |
1cfd6849 | 1462 | { |
500462a9 | 1463 | struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
c1ad348b TG |
1464 | u64 expires = KTIME_MAX; |
1465 | unsigned long nextevt; | |
46c8f0b0 | 1466 | bool is_max_delta; |
1cfd6849 | 1467 | |
dbd87b5a HC |
1468 | /* |
1469 | * Pretend that there is no timer pending if the cpu is offline. | |
1470 | * Possible pending timers will be migrated later to an active cpu. | |
1471 | */ | |
1472 | if (cpu_is_offline(smp_processor_id())) | |
e40468a5 TG |
1473 | return expires; |
1474 | ||
1cfd6849 | 1475 | spin_lock(&base->lock); |
500462a9 | 1476 | nextevt = __next_timer_interrupt(base); |
46c8f0b0 | 1477 | is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA); |
a683f390 TG |
1478 | base->next_expiry = nextevt; |
1479 | /* | |
041ad7bc TG |
1480 | * We have a fresh next event. Check whether we can forward the |
1481 | * base. We can only do that when @basej is past base->clk | |
1482 | * otherwise we might rewind base->clk. | |
a683f390 | 1483 | */ |
041ad7bc TG |
1484 | if (time_after(basej, base->clk)) { |
1485 | if (time_after(nextevt, basej)) | |
1486 | base->clk = basej; | |
1487 | else if (time_after(nextevt, base->clk)) | |
1488 | base->clk = nextevt; | |
1489 | } | |
23696838 | 1490 | |
a683f390 | 1491 | if (time_before_eq(nextevt, basej)) { |
500462a9 | 1492 | expires = basem; |
a683f390 TG |
1493 | base->is_idle = false; |
1494 | } else { | |
46c8f0b0 CM |
1495 | if (!is_max_delta) |
1496 | expires = basem + (nextevt - basej) * TICK_NSEC; | |
a683f390 TG |
1497 | /* |
1498 | * If we expect to sleep more than a tick, mark the base idle: | |
1499 | */ | |
1500 | if ((expires - basem) > TICK_NSEC) | |
1501 | base->is_idle = true; | |
e40468a5 | 1502 | } |
1cfd6849 TG |
1503 | spin_unlock(&base->lock); |
1504 | ||
c1ad348b | 1505 | return cmp_next_hrtimer_event(basem, expires); |
1cfd6849 | 1506 | } |
23696838 | 1507 | |
a683f390 TG |
1508 | /** |
1509 | * timer_clear_idle - Clear the idle state of the timer base | |
1510 | * | |
1511 | * Called with interrupts disabled | |
1512 | */ | |
1513 | void timer_clear_idle(void) | |
1514 | { | |
1515 | struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); | |
1516 | ||
1517 | /* | |
1518 | * We do this unlocked. The worst outcome is a remote enqueue sending | |
1519 | * a pointless IPI, but taking the lock would just make the window for | |
1520 | * sending the IPI a few instructions smaller for the cost of taking | |
1521 | * the lock in the exit from idle path. | |
1522 | */ | |
1523 | base->is_idle = false; | |
1524 | } | |
1525 | ||
23696838 AMG |
1526 | static int collect_expired_timers(struct timer_base *base, |
1527 | struct hlist_head *heads) | |
1528 | { | |
1529 | /* | |
1530 | * NOHZ optimization. After a long idle sleep we need to forward the | |
1531 | * base to current jiffies. Avoid a loop by searching the bitfield for | |
1532 | * the next expiring timer. | |
1533 | */ | |
1534 | if ((long)(jiffies - base->clk) > 2) { | |
1535 | unsigned long next = __next_timer_interrupt(base); | |
1536 | ||
1537 | /* | |
1538 | * If the next timer is ahead of time forward to current | |
a683f390 | 1539 | * jiffies, otherwise forward to the next expiry time: |
23696838 AMG |
1540 | */ |
1541 | if (time_after(next, jiffies)) { | |
1542 | /* The call site will increment clock! */ | |
1543 | base->clk = jiffies - 1; | |
1544 | return 0; | |
1545 | } | |
1546 | base->clk = next; | |
1547 | } | |
1548 | return __collect_expired_timers(base, heads); | |
1549 | } | |
1550 | #else | |
1551 | static inline int collect_expired_timers(struct timer_base *base, | |
1552 | struct hlist_head *heads) | |
1553 | { | |
1554 | return __collect_expired_timers(base, heads); | |
1555 | } | |
1da177e4 LT |
1556 | #endif |
1557 | ||
1da177e4 | 1558 | /* |
5b4db0c2 | 1559 | * Called from the timer interrupt handler to charge one tick to the current |
1da177e4 LT |
1560 | * process. user_tick is 1 if the tick is user time, 0 for system. |
1561 | */ | |
1562 | void update_process_times(int user_tick) | |
1563 | { | |
1564 | struct task_struct *p = current; | |
1da177e4 LT |
1565 | |
1566 | /* Note: this timer irq context must be accounted for as well. */ | |
fa13a5a1 | 1567 | account_process_tick(p, user_tick); |
1da177e4 | 1568 | run_local_timers(); |
c3377c2d | 1569 | rcu_check_callbacks(user_tick); |
e360adbe PZ |
1570 | #ifdef CONFIG_IRQ_WORK |
1571 | if (in_irq()) | |
76a33061 | 1572 | irq_work_tick(); |
e360adbe | 1573 | #endif |
1da177e4 | 1574 | scheduler_tick(); |
baa73d9e NP |
1575 | if (IS_ENABLED(CONFIG_POSIX_TIMERS)) |
1576 | run_posix_cpu_timers(p); | |
1da177e4 LT |
1577 | } |
1578 | ||
73420fea AMG |
1579 | /** |
1580 | * __run_timers - run all expired timers (if any) on this CPU. | |
1581 | * @base: the timer vector to be processed. | |
1582 | */ | |
1583 | static inline void __run_timers(struct timer_base *base) | |
1584 | { | |
1585 | struct hlist_head heads[LVL_DEPTH]; | |
1586 | int levels; | |
1587 | ||
1588 | if (!time_after_eq(jiffies, base->clk)) | |
1589 | return; | |
1590 | ||
1591 | spin_lock_irq(&base->lock); | |
1592 | ||
1593 | while (time_after_eq(jiffies, base->clk)) { | |
1594 | ||
1595 | levels = collect_expired_timers(base, heads); | |
1596 | base->clk++; | |
1597 | ||
1598 | while (levels--) | |
1599 | expire_timers(base, heads + levels); | |
1600 | } | |
1601 | base->running_timer = NULL; | |
1602 | spin_unlock_irq(&base->lock); | |
1603 | } | |
1604 | ||
1da177e4 LT |
1605 | /* |
1606 | * This function runs timers and the timer-tq in bottom half context. | |
1607 | */ | |
0766f788 | 1608 | static __latent_entropy void run_timer_softirq(struct softirq_action *h) |
1da177e4 | 1609 | { |
500462a9 | 1610 | struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
1da177e4 | 1611 | |
500462a9 TG |
1612 | __run_timers(base); |
1613 | if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && base->nohz_active) | |
1614 | __run_timers(this_cpu_ptr(&timer_bases[BASE_DEF])); | |
1da177e4 LT |
1615 | } |
1616 | ||
1617 | /* | |
1618 | * Called by the local, per-CPU timer interrupt on SMP. | |
1619 | */ | |
1620 | void run_local_timers(void) | |
1621 | { | |
4e85876a TG |
1622 | struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
1623 | ||
d3d74453 | 1624 | hrtimer_run_queues(); |
4e85876a TG |
1625 | /* Raise the softirq only if required. */ |
1626 | if (time_before(jiffies, base->clk)) { | |
1627 | if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->nohz_active) | |
1628 | return; | |
1629 | /* CPU is awake, so check the deferrable base. */ | |
1630 | base++; | |
1631 | if (time_before(jiffies, base->clk)) | |
1632 | return; | |
1633 | } | |
1da177e4 LT |
1634 | raise_softirq(TIMER_SOFTIRQ); |
1635 | } | |
1636 | ||
1da177e4 LT |
1637 | static void process_timeout(unsigned long __data) |
1638 | { | |
36c8b586 | 1639 | wake_up_process((struct task_struct *)__data); |
1da177e4 LT |
1640 | } |
1641 | ||
1642 | /** | |
1643 | * schedule_timeout - sleep until timeout | |
1644 | * @timeout: timeout value in jiffies | |
1645 | * | |
1646 | * Make the current task sleep until @timeout jiffies have | |
1647 | * elapsed. The routine will return immediately unless | |
1648 | * the current task state has been set (see set_current_state()). | |
1649 | * | |
1650 | * You can set the task state as follows - | |
1651 | * | |
1652 | * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to | |
4b7e9cf9 DA |
1653 | * pass before the routine returns unless the current task is explicitly |
1654 | * woken up, (e.g. by wake_up_process())". | |
1da177e4 LT |
1655 | * |
1656 | * %TASK_INTERRUPTIBLE - the routine may return early if a signal is | |
4b7e9cf9 DA |
1657 | * delivered to the current task or the current task is explicitly woken |
1658 | * up. | |
1da177e4 LT |
1659 | * |
1660 | * The current task state is guaranteed to be TASK_RUNNING when this | |
1661 | * routine returns. | |
1662 | * | |
1663 | * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule | |
1664 | * the CPU away without a bound on the timeout. In this case the return | |
1665 | * value will be %MAX_SCHEDULE_TIMEOUT. | |
1666 | * | |
4b7e9cf9 DA |
1667 | * Returns 0 when the timer has expired otherwise the remaining time in |
1668 | * jiffies will be returned. In all cases the return value is guaranteed | |
1669 | * to be non-negative. | |
1da177e4 | 1670 | */ |
7ad5b3a5 | 1671 | signed long __sched schedule_timeout(signed long timeout) |
1da177e4 LT |
1672 | { |
1673 | struct timer_list timer; | |
1674 | unsigned long expire; | |
1675 | ||
1676 | switch (timeout) | |
1677 | { | |
1678 | case MAX_SCHEDULE_TIMEOUT: | |
1679 | /* | |
1680 | * These two special cases are useful to be comfortable | |
1681 | * in the caller. Nothing more. We could take | |
1682 | * MAX_SCHEDULE_TIMEOUT from one of the negative value | |
1683 | * but I' d like to return a valid offset (>=0) to allow | |
1684 | * the caller to do everything it want with the retval. | |
1685 | */ | |
1686 | schedule(); | |
1687 | goto out; | |
1688 | default: | |
1689 | /* | |
1690 | * Another bit of PARANOID. Note that the retval will be | |
1691 | * 0 since no piece of kernel is supposed to do a check | |
1692 | * for a negative retval of schedule_timeout() (since it | |
1693 | * should never happens anyway). You just have the printk() | |
1694 | * that will tell you if something is gone wrong and where. | |
1695 | */ | |
5b149bcc | 1696 | if (timeout < 0) { |
1da177e4 | 1697 | printk(KERN_ERR "schedule_timeout: wrong timeout " |
5b149bcc AM |
1698 | "value %lx\n", timeout); |
1699 | dump_stack(); | |
1da177e4 LT |
1700 | current->state = TASK_RUNNING; |
1701 | goto out; | |
1702 | } | |
1703 | } | |
1704 | ||
1705 | expire = timeout + jiffies; | |
1706 | ||
c6f3a97f | 1707 | setup_timer_on_stack(&timer, process_timeout, (unsigned long)current); |
177ec0a0 | 1708 | __mod_timer(&timer, expire, false); |
1da177e4 LT |
1709 | schedule(); |
1710 | del_singleshot_timer_sync(&timer); | |
1711 | ||
c6f3a97f TG |
1712 | /* Remove the timer from the object tracker */ |
1713 | destroy_timer_on_stack(&timer); | |
1714 | ||
1da177e4 LT |
1715 | timeout = expire - jiffies; |
1716 | ||
1717 | out: | |
1718 | return timeout < 0 ? 0 : timeout; | |
1719 | } | |
1da177e4 LT |
1720 | EXPORT_SYMBOL(schedule_timeout); |
1721 | ||
8a1c1757 AM |
1722 | /* |
1723 | * We can use __set_current_state() here because schedule_timeout() calls | |
1724 | * schedule() unconditionally. | |
1725 | */ | |
64ed93a2 NA |
1726 | signed long __sched schedule_timeout_interruptible(signed long timeout) |
1727 | { | |
a5a0d52c AM |
1728 | __set_current_state(TASK_INTERRUPTIBLE); |
1729 | return schedule_timeout(timeout); | |
64ed93a2 NA |
1730 | } |
1731 | EXPORT_SYMBOL(schedule_timeout_interruptible); | |
1732 | ||
294d5cc2 MW |
1733 | signed long __sched schedule_timeout_killable(signed long timeout) |
1734 | { | |
1735 | __set_current_state(TASK_KILLABLE); | |
1736 | return schedule_timeout(timeout); | |
1737 | } | |
1738 | EXPORT_SYMBOL(schedule_timeout_killable); | |
1739 | ||
64ed93a2 NA |
1740 | signed long __sched schedule_timeout_uninterruptible(signed long timeout) |
1741 | { | |
a5a0d52c AM |
1742 | __set_current_state(TASK_UNINTERRUPTIBLE); |
1743 | return schedule_timeout(timeout); | |
64ed93a2 NA |
1744 | } |
1745 | EXPORT_SYMBOL(schedule_timeout_uninterruptible); | |
1746 | ||
69b27baf AM |
1747 | /* |
1748 | * Like schedule_timeout_uninterruptible(), except this task will not contribute | |
1749 | * to load average. | |
1750 | */ | |
1751 | signed long __sched schedule_timeout_idle(signed long timeout) | |
1752 | { | |
1753 | __set_current_state(TASK_IDLE); | |
1754 | return schedule_timeout(timeout); | |
1755 | } | |
1756 | EXPORT_SYMBOL(schedule_timeout_idle); | |
1757 | ||
1da177e4 | 1758 | #ifdef CONFIG_HOTPLUG_CPU |
494af3ed | 1759 | static void migrate_timer_list(struct timer_base *new_base, struct hlist_head *head) |
1da177e4 LT |
1760 | { |
1761 | struct timer_list *timer; | |
0eeda71b | 1762 | int cpu = new_base->cpu; |
1da177e4 | 1763 | |
1dabbcec TG |
1764 | while (!hlist_empty(head)) { |
1765 | timer = hlist_entry(head->first, struct timer_list, entry); | |
ec44bc7a | 1766 | detach_timer(timer, false); |
0eeda71b | 1767 | timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu; |
1da177e4 | 1768 | internal_add_timer(new_base, timer); |
1da177e4 | 1769 | } |
1da177e4 LT |
1770 | } |
1771 | ||
24f73b99 | 1772 | int timers_dead_cpu(unsigned int cpu) |
1da177e4 | 1773 | { |
494af3ed TG |
1774 | struct timer_base *old_base; |
1775 | struct timer_base *new_base; | |
500462a9 | 1776 | int b, i; |
1da177e4 LT |
1777 | |
1778 | BUG_ON(cpu_online(cpu)); | |
55c888d6 | 1779 | |
500462a9 TG |
1780 | for (b = 0; b < NR_BASES; b++) { |
1781 | old_base = per_cpu_ptr(&timer_bases[b], cpu); | |
1782 | new_base = get_cpu_ptr(&timer_bases[b]); | |
1783 | /* | |
1784 | * The caller is globally serialized and nobody else | |
1785 | * takes two locks at once, deadlock is not possible. | |
1786 | */ | |
1787 | spin_lock_irq(&new_base->lock); | |
1788 | spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); | |
1789 | ||
1790 | BUG_ON(old_base->running_timer); | |
1791 | ||
1792 | for (i = 0; i < WHEEL_SIZE; i++) | |
1793 | migrate_timer_list(new_base, old_base->vectors + i); | |
8def9060 | 1794 | |
500462a9 TG |
1795 | spin_unlock(&old_base->lock); |
1796 | spin_unlock_irq(&new_base->lock); | |
1797 | put_cpu_ptr(&timer_bases); | |
1798 | } | |
24f73b99 | 1799 | return 0; |
1da177e4 | 1800 | } |
1da177e4 | 1801 | |
3650b57f | 1802 | #endif /* CONFIG_HOTPLUG_CPU */ |
1da177e4 | 1803 | |
0eeda71b | 1804 | static void __init init_timer_cpu(int cpu) |
8def9060 | 1805 | { |
500462a9 TG |
1806 | struct timer_base *base; |
1807 | int i; | |
8def9060 | 1808 | |
500462a9 TG |
1809 | for (i = 0; i < NR_BASES; i++) { |
1810 | base = per_cpu_ptr(&timer_bases[i], cpu); | |
1811 | base->cpu = cpu; | |
1812 | spin_lock_init(&base->lock); | |
1813 | base->clk = jiffies; | |
1814 | } | |
8def9060 VK |
1815 | } |
1816 | ||
1817 | static void __init init_timer_cpus(void) | |
1da177e4 | 1818 | { |
8def9060 VK |
1819 | int cpu; |
1820 | ||
0eeda71b TG |
1821 | for_each_possible_cpu(cpu) |
1822 | init_timer_cpu(cpu); | |
8def9060 | 1823 | } |
e52b1db3 | 1824 | |
8def9060 VK |
1825 | void __init init_timers(void) |
1826 | { | |
8def9060 | 1827 | init_timer_cpus(); |
962cf36c | 1828 | open_softirq(TIMER_SOFTIRQ, run_timer_softirq); |
1da177e4 LT |
1829 | } |
1830 | ||
1da177e4 LT |
1831 | /** |
1832 | * msleep - sleep safely even with waitqueue interruptions | |
1833 | * @msecs: Time in milliseconds to sleep for | |
1834 | */ | |
1835 | void msleep(unsigned int msecs) | |
1836 | { | |
1837 | unsigned long timeout = msecs_to_jiffies(msecs) + 1; | |
1838 | ||
75bcc8c5 NA |
1839 | while (timeout) |
1840 | timeout = schedule_timeout_uninterruptible(timeout); | |
1da177e4 LT |
1841 | } |
1842 | ||
1843 | EXPORT_SYMBOL(msleep); | |
1844 | ||
1845 | /** | |
96ec3efd | 1846 | * msleep_interruptible - sleep waiting for signals |
1da177e4 LT |
1847 | * @msecs: Time in milliseconds to sleep for |
1848 | */ | |
1849 | unsigned long msleep_interruptible(unsigned int msecs) | |
1850 | { | |
1851 | unsigned long timeout = msecs_to_jiffies(msecs) + 1; | |
1852 | ||
75bcc8c5 NA |
1853 | while (timeout && !signal_pending(current)) |
1854 | timeout = schedule_timeout_interruptible(timeout); | |
1da177e4 LT |
1855 | return jiffies_to_msecs(timeout); |
1856 | } | |
1857 | ||
1858 | EXPORT_SYMBOL(msleep_interruptible); | |
5e7f5a17 | 1859 | |
5e7f5a17 | 1860 | /** |
b5227d03 | 1861 | * usleep_range - Sleep for an approximate time |
5e7f5a17 PP |
1862 | * @min: Minimum time in usecs to sleep |
1863 | * @max: Maximum time in usecs to sleep | |
b5227d03 BH |
1864 | * |
1865 | * In non-atomic context where the exact wakeup time is flexible, use | |
1866 | * usleep_range() instead of udelay(). The sleep improves responsiveness | |
1867 | * by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces | |
1868 | * power usage by allowing hrtimers to take advantage of an already- | |
1869 | * scheduled interrupt instead of scheduling a new one just for this sleep. | |
5e7f5a17 | 1870 | */ |
2ad5d327 | 1871 | void __sched usleep_range(unsigned long min, unsigned long max) |
5e7f5a17 | 1872 | { |
6c5e9059 DA |
1873 | ktime_t exp = ktime_add_us(ktime_get(), min); |
1874 | u64 delta = (u64)(max - min) * NSEC_PER_USEC; | |
1875 | ||
1876 | for (;;) { | |
1877 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
1878 | /* Do not return before the requested sleep time has elapsed */ | |
1879 | if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS)) | |
1880 | break; | |
1881 | } | |
5e7f5a17 PP |
1882 | } |
1883 | EXPORT_SYMBOL(usleep_range); |