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perf_counter: Fix ctx->mutex vs counter->mutex inversion

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Simon triggered a lockdep inversion report about us taking ctx->mutex
vs counter->mutex in inverse orders. Fix that up.

Reported-by: Simon Holm Thøgersen <odie@cs.aau.dk>
Tested-by: Simon Holm Thøgersen <odie@cs.aau.dk>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-06-15 15:05:12 +02:00 committed by Ingo Molnar
parent 613d860229
commit 75f937f24b
1 changed files with 11 additions and 23 deletions
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34
kernel/perf_counter.c
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@ -1620,22 +1620,6 @@ static void perf_counter_reset(struct perf_counter *counter)
perf_counter_update_userpage(counter);
}
static void perf_counter_for_each_sibling(struct perf_counter *counter,
void (*func)(struct perf_counter *))
{
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *sibling;
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
counter = counter->group_leader;
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
func(sibling);
mutex_unlock(&ctx->mutex);
}
/*
* Holding the top-level counter's child_mutex means that any
* descendant process that has inherited this counter will block
@ -1658,14 +1642,18 @@ static void perf_counter_for_each_child(struct perf_counter *counter,
static void perf_counter_for_each(struct perf_counter *counter,
void (*func)(struct perf_counter *))
{
struct perf_counter *child;
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *sibling;
WARN_ON_ONCE(counter->ctx->parent_ctx);
mutex_lock(&counter->child_mutex);
perf_counter_for_each_sibling(counter, func);
list_for_each_entry(child, &counter->child_list, child_list)
perf_counter_for_each_sibling(child, func);
mutex_unlock(&counter->child_mutex);
WARN_ON_ONCE(ctx->parent_ctx);
mutex_lock(&ctx->mutex);
counter = counter->group_leader;
perf_counter_for_each_child(counter, func);
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
perf_counter_for_each_child(counter, func);
mutex_unlock(&ctx->mutex);
}
static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)