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| author | Oleg Nesterov <oleg@redhat.com> | 2011-01-21 17:45:47 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-01-21 21:08:16 (GMT) |
| commit | 806839b22cbda90176d7f8d421889bddd7826e93 (patch) | |
| tree | 3ee967f97fa5e29ada85fb1d60142c75503e0ffd | |
| parent | 547e9fd7d328af261f184bf66effc5033c886498 (diff) | |
| download | linux-806839b22cbda90176d7f8d421889bddd7826e93.tar.xz | |
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@elte.hu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: acme@redhat.com
Cc: paulus@samba.org
Cc: stern@rowland.harvard.edu
Cc: a.p.zijlstra@chello.nl
Cc: fweisbec@gmail.com
Cc: roland@redhat.com
Cc: prasad@linux.vnet.ibm.com
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
LKML-Reference: <20110121174547.GA8796@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | 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); /* |