mirror of
https://github.com/torvalds/linux
synced 2024-10-25 12:49:03 +00:00
fe8e5b5a60
When we call the profile_enable() callback of an event, we release the shared perf event tracing buffers unconditionnaly in the failure path. This is wrong because there may be other users of these. Then check the total refcount before doing this. Reported-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Li Zefan <lizf@cn.fujitsu.com>
126 lines
2.5 KiB
C
126 lines
2.5 KiB
C
/*
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* trace event based perf counter profiling
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*
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* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
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*
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*/
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#include <linux/module.h>
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#include "trace.h"
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/*
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* We can't use a size but a type in alloc_percpu()
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* So let's create a dummy type that matches the desired size
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*/
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typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
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char *trace_profile_buf;
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EXPORT_SYMBOL_GPL(trace_profile_buf);
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char *trace_profile_buf_nmi;
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EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
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/* Count the events in use (per event id, not per instance) */
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static int total_profile_count;
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static int ftrace_profile_enable_event(struct ftrace_event_call *event)
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{
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char *buf;
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int ret = -ENOMEM;
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if (atomic_inc_return(&event->profile_count))
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return 0;
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if (!total_profile_count) {
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buf = (char *)alloc_percpu(profile_buf_t);
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if (!buf)
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goto fail_buf;
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rcu_assign_pointer(trace_profile_buf, buf);
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buf = (char *)alloc_percpu(profile_buf_t);
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if (!buf)
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goto fail_buf_nmi;
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rcu_assign_pointer(trace_profile_buf_nmi, buf);
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}
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ret = event->profile_enable();
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if (!ret) {
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total_profile_count++;
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return 0;
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}
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fail_buf_nmi:
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if (!total_profile_count) {
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kfree(trace_profile_buf_nmi);
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kfree(trace_profile_buf);
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trace_profile_buf_nmi = NULL;
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trace_profile_buf = NULL;
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}
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fail_buf:
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atomic_dec(&event->profile_count);
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return ret;
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}
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int ftrace_profile_enable(int event_id)
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{
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struct ftrace_event_call *event;
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int ret = -EINVAL;
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mutex_lock(&event_mutex);
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list_for_each_entry(event, &ftrace_events, list) {
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if (event->id == event_id && event->profile_enable &&
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try_module_get(event->mod)) {
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ret = ftrace_profile_enable_event(event);
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break;
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}
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}
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mutex_unlock(&event_mutex);
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return ret;
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}
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static void ftrace_profile_disable_event(struct ftrace_event_call *event)
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{
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char *buf, *nmi_buf;
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if (!atomic_add_negative(-1, &event->profile_count))
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return;
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event->profile_disable();
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if (!--total_profile_count) {
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buf = trace_profile_buf;
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rcu_assign_pointer(trace_profile_buf, NULL);
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nmi_buf = trace_profile_buf_nmi;
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rcu_assign_pointer(trace_profile_buf_nmi, NULL);
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/*
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* Ensure every events in profiling have finished before
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* releasing the buffers
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*/
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synchronize_sched();
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free_percpu(buf);
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free_percpu(nmi_buf);
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}
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}
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void ftrace_profile_disable(int event_id)
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{
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struct ftrace_event_call *event;
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mutex_lock(&event_mutex);
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list_for_each_entry(event, &ftrace_events, list) {
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if (event->id == event_id) {
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ftrace_profile_disable_event(event);
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module_put(event->mod);
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break;
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}
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}
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mutex_unlock(&event_mutex);
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}
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