perf_counter: Sanitize context locking
Ensure we're consistent with the context locks.
context->mutex
context->lock
list_{add,del}_counter();
so that either lock is sufficient to stabilize the context.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.618790733@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 679c3b5..d162d2f 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -597,6 +597,8 @@
/*
* Cross CPU call to install and enable a performance counter
+ *
+ * Must be called with ctx->mutex held
*/
static void __perf_install_in_context(void *info)
{
@@ -1496,13 +1498,13 @@
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *sibling;
- spin_lock_irq(&ctx->lock);
+ mutex_lock(&ctx->mutex);
counter = counter->group_leader;
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
func(sibling);
- spin_unlock_irq(&ctx->lock);
+ mutex_unlock(&ctx->mutex);
}
static void perf_counter_for_each_child(struct perf_counter *counter,
@@ -3414,7 +3416,10 @@
struct perf_counter *parent_counter;
update_counter_times(child_counter);
+
+ spin_lock_irq(&child_ctx->lock);
list_del_counter(child_counter, child_ctx);
+ spin_unlock_irq(&child_ctx->lock);
parent_counter = child_counter->parent;
/*