Commit-ID: b58f6b0dd3d677338b9065388cc2cc942b86338e
Gitweb: http://git.kernel.org/tip/b58f6b0dd3d677338b9065388cc2cc942b86338e
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 7 Jun 2011 00:23:28 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 7 Jun 2011 13:02:41 +0200
perf, core: Fix initial task_ctx/event installation
A lost Quilt refresh of 2c29ef0fef8 (perf: Simplify and fix
__perf_install_in_context()) is causing grief and lockups,
reported by Jiri Olsa.
When installing an event in a task context, there's a number of
issues:
- there might not be an existing task context, in which case
we should install the now current context;
- there might already be a context, not the current one, in
which case we should de-schedule the old and install the new;
these cases were dealt with in the lost refresh, however there is one
further case that was found in testing:
- there might already be a context, the current one, in which
case we should still de-schedule, and should take care
to re-install it (note that task_ctx_sched_out() clears
cpuctx->task_ctx).
Reported-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1307399008.2497.971.camel@laptop
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/events/core.c | 28 +++++++++++++++++-----------
1 files changed, 17 insertions(+), 11 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ba89f40..5e8c7b1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1505,25 +1505,31 @@ static int __perf_install_in_context(void *info)
struct perf_event_context *task_ctx = cpuctx->task_ctx;
struct task_struct *task = current;
- perf_ctx_lock(cpuctx, cpuctx->task_ctx);
+ perf_ctx_lock(cpuctx, task_ctx);
perf_pmu_disable(cpuctx->ctx.pmu);
/*
* If there was an active task_ctx schedule it out.
*/
- if (task_ctx) {
+ if (task_ctx)
task_ctx_sched_out(task_ctx);
- /*
- * If the context we're installing events in is not the
- * active task_ctx, flip them.
- */
- if (ctx->task && task_ctx != ctx) {
- raw_spin_unlock(&cpuctx->ctx.lock);
- raw_spin_lock(&ctx->lock);
- cpuctx->task_ctx = task_ctx = ctx;
- }
+
+ /*
+ * If the context we're installing events in is not the
+ * active task_ctx, flip them.
+ */
+ if (ctx->task && task_ctx != ctx) {
+ if (task_ctx)
+ raw_spin_unlock(&task_ctx->lock);
+ raw_spin_lock(&ctx->lock);
+ task_ctx = ctx;
+ }
+
+ if (task_ctx) {
+ cpuctx->task_ctx = task_ctx;
task = task_ctx->task;
}
+
cpu_ctx_sched_out(cpuctx, EVENT_ALL);
update_context_time(ctx);
--
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