summaryrefslogtreecommitdiff
path: root/kernel
diff options
context:
space:
mode:
authorStephane Eranian <eranian@google.com>2015-11-12 10:00:04 (GMT)
committerIngo Molnar <mingo@kernel.org>2015-11-23 08:21:03 (GMT)
commit614e4c4ebc75517295bccd29b20ddbc5b52af6fc (patch)
tree67931aaaac4c9e81176140293348f3582ef2a742 /kernel
parentddaaf4e291dd63db0667991e4a335fcf3a7df13e (diff)
downloadlinux-614e4c4ebc75517295bccd29b20ddbc5b52af6fc.tar.xz
perf/core: Robustify the perf_cgroup_from_task() RCU checks
This patch reinforces the lockdep checks performed by perf_cgroup_from_tsk() by passing the perf_event_context whenever possible. It is okay to not hold the RCU read lock when we know we hold the ctx->lock. This patch makes sure this property holds. In some functions, such as perf_cgroup_sched_in(), we do not pass the context because we are sure we are holding the RCU read lock. Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: edumazet@google.com Link: http://lkml.kernel.org/r/1447322404-10920-3-git-send-email-eranian@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 60e71ca..1ac857a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -435,7 +435,7 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
if (!is_cgroup_event(event))
return;
- cgrp = perf_cgroup_from_task(current);
+ cgrp = perf_cgroup_from_task(current, event->ctx);
/*
* Do not update time when cgroup is not active
*/
@@ -458,7 +458,7 @@ perf_cgroup_set_timestamp(struct task_struct *task,
if (!task || !ctx->nr_cgroups)
return;
- cgrp = perf_cgroup_from_task(task);
+ cgrp = perf_cgroup_from_task(task, ctx);
info = this_cpu_ptr(cgrp->info);
info->timestamp = ctx->timestamp;
}
@@ -521,8 +521,10 @@ static void perf_cgroup_switch(struct task_struct *task, int mode)
* set cgrp before ctxsw in to allow
* event_filter_match() to not have to pass
* task around
+ * we pass the cpuctx->ctx to perf_cgroup_from_task()
+ * because cgorup events are only per-cpu
*/
- cpuctx->cgrp = perf_cgroup_from_task(task);
+ cpuctx->cgrp = perf_cgroup_from_task(task, &cpuctx->ctx);
cpu_ctx_sched_in(cpuctx, EVENT_ALL, task);
}
perf_pmu_enable(cpuctx->ctx.pmu);
@@ -542,15 +544,17 @@ static inline void perf_cgroup_sched_out(struct task_struct *task,
rcu_read_lock();
/*
* we come here when we know perf_cgroup_events > 0
+ * we do not need to pass the ctx here because we know
+ * we are holding the rcu lock
*/
- cgrp1 = perf_cgroup_from_task(task);
+ 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);
+ cgrp2 = perf_cgroup_from_task(next, NULL);
/*
* only schedule out current cgroup events if we know
@@ -572,11 +576,13 @@ static inline void perf_cgroup_sched_in(struct task_struct *prev,
rcu_read_lock();
/*
* we come here when we know perf_cgroup_events > 0
+ * we do not need to pass the ctx here because we know
+ * we are holding the rcu lock
*/
- cgrp1 = perf_cgroup_from_task(task);
+ cgrp1 = perf_cgroup_from_task(task, NULL);
/* prev can never be NULL */
- cgrp2 = perf_cgroup_from_task(prev);
+ cgrp2 = perf_cgroup_from_task(prev, NULL);
/*
* only need to schedule in cgroup events if we are changing