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perf: Fix cgroup scheduling in perf_enable_on_exec() 

There is a comment that states that perf_event_context_sched_in() will
also switch in the cgroup events, I cannot find it does so. Therefore
all the resulting logic goes out the window too.

Clean that up.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-01-08 09:29:16 +01:00 committed by Ingo Molnar
parent 7e41d17753
commit 70a0165752
1 changed files with 7 additions and 24 deletions
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31
kernel/events/core.c
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@ -579,13 +579,7 @@ static inline void perf_cgroup_sched_out(struct task_struct *task,
* we are holding the rcu lock
*/
cgrp1 = perf_cgroup_from_task(task, NULL);
/*
* next is NULL when called from perf_event_enable_on_exec()
* that will systematically cause a cgroup_switch()
*/
if (next)
cgrp2 = perf_cgroup_from_task(next, NULL);
cgrp2 = perf_cgroup_from_task(next, NULL);
/*
* only schedule out current cgroup events if we know
@ -611,8 +605,6 @@ static inline void perf_cgroup_sched_in(struct task_struct *prev,
* we are holding the rcu lock
*/
cgrp1 = perf_cgroup_from_task(task, NULL);
/* prev can never be NULL */
cgrp2 = perf_cgroup_from_task(prev, NULL);
/*
@ -1450,11 +1442,14 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
if (is_cgroup_event(event)) {
ctx->nr_cgroups--;
/*
* Because cgroup events are always per-cpu events, this will
* always be called from the right CPU.
*/
cpuctx = __get_cpu_context(ctx);
/*
* if there are no more cgroup events
* then cler cgrp to avoid stale pointer
* in update_cgrp_time_from_cpuctx()
* If there are no more cgroup events then clear cgrp to avoid
* stale pointer in update_cgrp_time_from_cpuctx().
*/
if (!ctx->nr_cgroups)
cpuctx->cgrp = NULL;
@ -3118,15 +3113,6 @@ static void perf_event_enable_on_exec(int ctxn)
if (!ctx || !ctx->nr_events)
goto out;
/*
* We must ctxsw out cgroup events to avoid conflict
* when invoking perf_task_event_sched_in() later on
* in this function. Otherwise we end up trying to
* ctxswin cgroup events which are already scheduled
* in.
*/
perf_cgroup_sched_out(current, NULL);
raw_spin_lock(&ctx->lock);
task_ctx_sched_out(ctx);
@ -3144,9 +3130,6 @@ static void perf_event_enable_on_exec(int ctxn)
raw_spin_unlock(&ctx->lock);
/*
* Also calls ctxswin for cgroup events, if any:
*/
perf_event_context_sched_in(ctx, ctx->task);
out:
local_irq_restore(flags);