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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - kernel/trace/trace_event_profile.c
2 * trace event based perf counter profiling
4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
8 #include <linux/module.h>
12 * We can't use a size but a type in alloc_percpu()
13 * So let's create a dummy type that matches the desired size
15 typedef struct {char buf
[FTRACE_MAX_PROFILE_SIZE
];} profile_buf_t
;
17 char *trace_profile_buf
;
18 EXPORT_SYMBOL_GPL(trace_profile_buf
);
20 char *trace_profile_buf_nmi
;
21 EXPORT_SYMBOL_GPL(trace_profile_buf_nmi
);
23 /* Count the events in use (per event id, not per instance) */
24 static int total_profile_count
;
26 static int ftrace_profile_enable_event(struct ftrace_event_call
*event
)
31 if (atomic_inc_return(&event
->profile_count
))
34 if (!total_profile_count
) {
35 buf
= (char *)alloc_percpu(profile_buf_t
);
39 rcu_assign_pointer(trace_profile_buf
, buf
);
41 buf
= (char *)alloc_percpu(profile_buf_t
);
45 rcu_assign_pointer(trace_profile_buf_nmi
, buf
);
48 ret
= event
->profile_enable();
50 total_profile_count
++;
55 if (!total_profile_count
) {
56 free_percpu(trace_profile_buf_nmi
);
57 free_percpu(trace_profile_buf
);
58 trace_profile_buf_nmi
= NULL
;
59 trace_profile_buf
= NULL
;
62 atomic_dec(&event
->profile_count
);
67 int ftrace_profile_enable(int event_id
)
69 struct ftrace_event_call
*event
;
72 mutex_lock(&event_mutex
);
73 list_for_each_entry(event
, &ftrace_events
, list
) {
74 if (event
->id
== event_id
&& event
->profile_enable
&&
75 try_module_get(event
->mod
)) {
76 ret
= ftrace_profile_enable_event(event
);
80 mutex_unlock(&event_mutex
);
85 static void ftrace_profile_disable_event(struct ftrace_event_call
*event
)
89 if (!atomic_add_negative(-1, &event
->profile_count
))
92 event
->profile_disable();
94 if (!--total_profile_count
) {
95 buf
= trace_profile_buf
;
96 rcu_assign_pointer(trace_profile_buf
, NULL
);
98 nmi_buf
= trace_profile_buf_nmi
;
99 rcu_assign_pointer(trace_profile_buf_nmi
, NULL
);
102 * Ensure every events in profiling have finished before
103 * releasing the buffers
108 free_percpu(nmi_buf
);
112 void ftrace_profile_disable(int event_id
)
114 struct ftrace_event_call
*event
;
116 mutex_lock(&event_mutex
);
117 list_for_each_entry(event
, &ftrace_events
, list
) {
118 if (event
->id
== event_id
) {
119 ftrace_profile_disable_event(event
);
120 module_put(event
->mod
);
124 mutex_unlock(&event_mutex
);