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perf_events, trace: Fix probe unregister race

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tracepoint_probe_unregister() does not synchronize against the probe
callbacks, so do that explicitly. This properly serializes the callbacks
and the free of the data used therein.

Also, use this_cpu_ptr() where possible.

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1274438476.1674.1702.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-05-21 12:31:09 +02:00 committed by Ingo Molnar
parent 8a49542c05
commit 3771f07711
4 changed files with 13 additions and 7 deletions
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2
include/trace/ftrace.h
View File

@ -725,7 +725,7 @@ perf_trace_##call(void *__data, proto) \
\
{ assign; } \
\
head = per_cpu_ptr(event_call->perf_events, smp_processor_id());\
head = this_cpu_ptr(event_call->perf_events); \
perf_trace_buf_submit(entry, __entry_size, rctx, __addr, \
__count, &__regs, head); \
}

10
kernel/trace/trace_event_perf.c
View File

@ -116,7 +116,7 @@ int perf_trace_enable(struct perf_event *p_event)
if (WARN_ON_ONCE(!list))
return -EINVAL;
list = per_cpu_ptr(list, smp_processor_id());
list = this_cpu_ptr(list);
hlist_add_head_rcu(&p_event->hlist_entry, list);
return 0;
@ -142,6 +142,12 @@ void perf_trace_destroy(struct perf_event *p_event)
tp_event->class->perf_probe,
tp_event);
/*
* Ensure our callback won't be called anymore. See
* tracepoint_probe_unregister() and __DO_TRACE().
*/
synchronize_sched();
free_percpu(tp_event->perf_events);
tp_event->perf_events = NULL;
@ -169,7 +175,7 @@ __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
if (*rctxp < 0)
return NULL;
raw_data = per_cpu_ptr(perf_trace_buf[*rctxp], smp_processor_id());
raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
/* zero the dead bytes from align to not leak stack to user */
memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));

4
kernel/trace/trace_kprobe.c
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@ -1359,7 +1359,7 @@ static __kprobes void kprobe_perf_func(struct kprobe *kp,
for (i = 0; i < tp->nr_args; i++)
call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
head = per_cpu_ptr(call->perf_events, smp_processor_id());
head = this_cpu_ptr(call->perf_events);
perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
}
@ -1392,7 +1392,7 @@ static __kprobes void kretprobe_perf_func(struct kretprobe_instance *ri,
for (i = 0; i < tp->nr_args; i++)
call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
head = per_cpu_ptr(call->perf_events, smp_processor_id());
head = this_cpu_ptr(call->perf_events);
perf_trace_buf_submit(entry, size, rctx, entry->ret_ip, 1, regs, head);
}

4
kernel/trace/trace_syscalls.c
View File

@ -519,7 +519,7 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
syscall_get_arguments(current, regs, 0, sys_data->nb_args,
(unsigned long *)&rec->args);
head = per_cpu_ptr(sys_data->enter_event->perf_events, smp_processor_id());
head = this_cpu_ptr(sys_data->enter_event->perf_events);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
}
@ -595,7 +595,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
rec->nr = syscall_nr;
rec->ret = syscall_get_return_value(current, regs);
head = per_cpu_ptr(sys_data->exit_event->perf_events, smp_processor_id());
head = this_cpu_ptr(sys_data->exit_event->perf_events);
perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
}