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authorSteven Rostedt <srostedt@redhat.com>2009-03-26 10:25:24 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-04-23 23:01:36 -0400
commit9be24414aad047dcf9d8d2a9a929321536c7ebec (patch)
treec4299c263acf1859ff59a3cb03a26826e7d57660 /kernel/trace/trace_sched_wakeup.c
parent6a74aa40907757ec98d8710ff66cd4cfe064e7d8 (diff)
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tracing/wakeup: move access to wakeup_cpu into spinlock
The code had the following outside the lock: if (next != wakeup_task) return; pc = preempt_count(); /* The task we are waiting for is waking up */ data = wakeup_trace->data[wakeup_cpu]; On initialization, wakeup_task is NULL and wakeup_cpu -1. This code is not under a lock. If wakeup_task is set on another CPU as that task is waking up, we can see the wakeup_task before wakeup_cpu is set. If we read wakeup_cpu while it is still -1 then we will have a bad data pointer. This patch moves the reading of wakeup_cpu within the protection of the spinlock used to protect the writing of wakeup_cpu and wakeup_task. [ Impact: remove possible race causing invalid pointer dereference ] Reported-by: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel/trace/trace_sched_wakeup.c')
-rw-r--r--kernel/trace/trace_sched_wakeup.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index b8b13c5540f..eacb2722517 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -138,9 +138,6 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
pc = preempt_count();
- /* The task we are waiting for is waking up */
- data = wakeup_trace->data[wakeup_cpu];
-
/* disable local data, not wakeup_cpu data */
cpu = raw_smp_processor_id();
disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
@@ -154,6 +151,9 @@ probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
if (unlikely(!tracer_enabled || next != wakeup_task))
goto out_unlock;
+ /* The task we are waiting for is waking up */
+ data = wakeup_trace->data[wakeup_cpu];
+
trace_function(wakeup_trace, CALLER_ADDR0, CALLER_ADDR1, flags, pc);
tracing_sched_switch_trace(wakeup_trace, prev, next, flags, pc);