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d7b2902c JS |
1 | /* Demo leapsecond deadlock |
2 | * by: John Stultz (john.stultz@linaro.org) | |
3 | * (C) Copyright IBM 2012 | |
4 | * (C) Copyright 2013, 2015 Linaro Limited | |
5 | * Licensed under the GPL | |
6 | * | |
7 | * This test demonstrates leapsecond deadlock that is possibe | |
8 | * on kernels from 2.6.26 to 3.3. | |
9 | * | |
10 | * WARNING: THIS WILL LIKELY HARDHANG SYSTEMS AND MAY LOSE DATA | |
11 | * RUN AT YOUR OWN RISK! | |
12 | * To build: | |
13 | * $ gcc leapcrash.c -o leapcrash -lrt | |
14 | */ | |
15 | ||
16 | ||
17 | ||
18 | #include <stdio.h> | |
19 | #include <stdlib.h> | |
20 | #include <time.h> | |
21 | #include <sys/time.h> | |
22 | #include <sys/timex.h> | |
23 | #include <string.h> | |
24 | #include <signal.h> | |
d7b2902c | 25 | #include "../kselftest.h" |
d7b2902c JS |
26 | |
27 | /* clear NTP time_status & time_state */ | |
28 | int clear_time_state(void) | |
29 | { | |
30 | struct timex tx; | |
31 | int ret; | |
32 | ||
33 | /* | |
34 | * We have to call adjtime twice here, as kernels | |
35 | * prior to 6b1859dba01c7 (included in 3.5 and | |
36 | * -stable), had an issue with the state machine | |
37 | * and wouldn't clear the STA_INS/DEL flag directly. | |
38 | */ | |
39 | tx.modes = ADJ_STATUS; | |
40 | tx.status = STA_PLL; | |
41 | ret = adjtimex(&tx); | |
42 | ||
43 | tx.modes = ADJ_STATUS; | |
44 | tx.status = 0; | |
45 | ret = adjtimex(&tx); | |
46 | ||
47 | return ret; | |
48 | } | |
49 | ||
50 | /* Make sure we cleanup on ctrl-c */ | |
51 | void handler(int unused) | |
52 | { | |
53 | clear_time_state(); | |
54 | exit(0); | |
55 | } | |
56 | ||
57 | ||
58 | int main(void) | |
59 | { | |
60 | struct timex tx; | |
61 | struct timespec ts; | |
62 | time_t next_leap; | |
63 | int count = 0; | |
64 | ||
65 | setbuf(stdout, NULL); | |
66 | ||
67 | signal(SIGINT, handler); | |
68 | signal(SIGKILL, handler); | |
69 | printf("This runs for a few minutes. Press ctrl-c to stop\n"); | |
70 | ||
71 | clear_time_state(); | |
72 | ||
73 | ||
74 | /* Get the current time */ | |
75 | clock_gettime(CLOCK_REALTIME, &ts); | |
76 | ||
77 | /* Calculate the next possible leap second 23:59:60 GMT */ | |
78 | next_leap = ts.tv_sec; | |
79 | next_leap += 86400 - (next_leap % 86400); | |
80 | ||
81 | for (count = 0; count < 20; count++) { | |
82 | struct timeval tv; | |
83 | ||
84 | ||
85 | /* set the time to 2 seconds before the leap */ | |
86 | tv.tv_sec = next_leap - 2; | |
87 | tv.tv_usec = 0; | |
88 | if (settimeofday(&tv, NULL)) { | |
89 | printf("Error: You're likely not running with proper (ie: root) permissions\n"); | |
90 | return ksft_exit_fail(); | |
91 | } | |
92 | tx.modes = 0; | |
93 | adjtimex(&tx); | |
94 | ||
95 | /* hammer on adjtime w/ STA_INS */ | |
96 | while (tx.time.tv_sec < next_leap + 1) { | |
97 | /* Set the leap second insert flag */ | |
98 | tx.modes = ADJ_STATUS; | |
99 | tx.status = STA_INS; | |
100 | adjtimex(&tx); | |
101 | } | |
102 | clear_time_state(); | |
103 | printf("."); | |
19de0f85 | 104 | fflush(stdout); |
d7b2902c JS |
105 | } |
106 | printf("[OK]\n"); | |
107 | return ksft_exit_pass(); | |
108 | } |