[PATCH 06/14] perf, core: always switch pmu specific data during context switch

[Yan, Zheng]

If two tasks were both forked from the same parent task, Events in their perf
task contexts can be the same. Perf core optimizes context switch oout in this
case.

Previous patch inroduces pmu specific data. The data is task specific, so we
should switch the data even when context switch is optimized out.

Signed-off-by: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
---
 kernel/events/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index b6650ab..d6d8dea 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2319,6 +2319,8 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
 			next->perf_event_ctxp[ctxn] = ctx;
 			ctx->task = next;
 			next_ctx->task = task;
+			ctx->task_ctx_data = xchg(&next_ctx->task_ctx_data,
+						  ctx->task_ctx_data);
 			do_switch = 0;
 
 			perf_event_sync_stat(ctx, next_ctx);
-- 
1.8.4.2

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