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authorSteven Rostedt <rostedt@goodmis.org>2008-05-12 21:20:56 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 21:15:59 +0200
commit30afdcb1de0a37a2086145a82ca3febebe47d019 (patch)
tree866c4d195207ac37d4477f9ce09d429085532180
parentd15f57f23eaba975309a153b23699cd0c0236974 (diff)
ftrace: selftest protect againt max flip
There is a slight race condition in the selftest where the max update of the wakeup and irqs/preemption off tests can be doing a max update as the buffers are being tested. If this happens the system can crash with a GPF. This patch adds the max update spinlock around the checking of the buffers to prevent such a race. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--kernel/trace/trace_selftest.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 83e55a2000cc..395274e783b3 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -82,10 +82,12 @@ trace_test_buffer_cpu(struct trace_array *tr, struct trace_array_cpu *data)
*/
static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
{
- unsigned long cnt = 0;
- int cpu;
- int ret = 0;
+ unsigned long flags, cnt = 0;
+ int cpu, ret = 0;
+ /* Don't allow flipping of max traces now */
+ raw_local_irq_save(flags);
+ __raw_spin_lock(&ftrace_max_lock);
for_each_possible_cpu(cpu) {
if (!head_page(tr->data[cpu]))
continue;
@@ -96,6 +98,8 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
if (ret)
break;
}
+ __raw_spin_unlock(&ftrace_max_lock);
+ raw_local_irq_restore(flags);
if (count)
*count = cnt;