Commit-ID: 806839b22cbda90176d7f8d421889bddd7826e93 Gitweb: http://git.kernel.org/tip/806839b22cbda90176d7f8d421889bddd7826e93 Author: Oleg Nesterov <oleg@xxxxxxxxxx> AuthorDate: Fri, 21 Jan 2011 18:45:47 +0100 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Fri, 21 Jan 2011 22:08:16 +0100 perf: perf_event_exit_task_context: s/rcu_dereference/rcu_dereference_raw/ In theory, almost every user of task->child->perf_event_ctxp[] is wrong. find_get_context() can install the new context at any moment, we need read_barrier_depends(). dbe08d82ce3967ccdf459f7951d02589cf967300 "perf: Fix find_get_context() vs perf_event_exit_task() race" added rcu_dereference() into perf_event_exit_task_context() to make the precedent, but this makes __rcu_dereference_check() unhappy. Use rcu_dereference_raw() to shut up the warning. Reported-by: Ingo Molnar <mingo@xxxxxxx> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: acme@xxxxxxxxxx Cc: paulus@xxxxxxxxx Cc: stern@xxxxxxxxxxxxxxxxxxx Cc: a.p.zijlstra@xxxxxxxxx Cc: fweisbec@xxxxxxxxx Cc: roland@xxxxxxxxxx Cc: prasad@xxxxxxxxxxxxxxxxxx Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> LKML-Reference: <20110121174547.GA8796@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- kernel/perf_event.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index c5fa717..126a302 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -6136,7 +6136,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn) * scheduled, so we are now safe from rescheduling changing * our context. */ - child_ctx = rcu_dereference(child->perf_event_ctxp[ctxn]); + child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]); task_ctx_sched_out(child_ctx, EVENT_ALL); /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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