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perf_counter: fix uninitialized usage of event_list 

Impact: fix boot crash

When doing the generic context switch event I ran into some early
boot hangs, which were caused by inf func recursion (event, fault,
event, fault).

I eventually tracked it down to event_list not being initialized
at the time of the first event. Fix this.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Orig-LKML-Reference: <20090319194233.195392657@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-03-19 20:26:11 +01:00 committed by Ingo Molnar
parent b6c5a71da1
commit 01ef09d9ff
2 changed files with 3 additions and 1 deletions
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2
include/linux/init_task.h
View File

@ -124,6 +124,8 @@ extern struct cred init_cred;
# define INIT_PERF_COUNTERS(tsk) \
.perf_counter_ctx.counter_list = \
LIST_HEAD_INIT(tsk.perf_counter_ctx.counter_list), \
.perf_counter_ctx.event_list = \
LIST_HEAD_INIT(tsk.perf_counter_ctx.event_list), \
.perf_counter_ctx.lock = \
__SPIN_LOCK_UNLOCKED(tsk.perf_counter_ctx.lock),
#else

2
kernel/perf_counter.c
View File

@ -1506,7 +1506,7 @@ static void perf_swcounter_ctx_event(struct perf_counter_context *ctx,
{
struct perf_counter *counter;
if (list_empty(&ctx->event_list))
if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list))
return;
rcu_read_lock();