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perf: Sanitize the RCU logic 

Simplify things and simply synchronize against two RCU variants for
PMU unregister -- we don't care about performance, its module unload
if anything.

Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-09-13 11:06:55 +02:00 committed by Ingo Molnar
parent b0b2072df3
commit cde8e88498
1 changed files with 9 additions and 8 deletions
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17
kernel/perf_event.c
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@ -3810,7 +3810,7 @@ static void perf_event_task_event(struct perf_task_event *task_event)
struct pmu *pmu;
int ctxn;
rcu_read_lock_sched();
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
perf_event_task_ctx(&cpuctx->ctx, task_event);
@ -3825,7 +3825,7 @@ static void perf_event_task_event(struct perf_task_event *task_event)
if (ctx)
perf_event_task_ctx(ctx, task_event);
}
rcu_read_unlock_sched();
rcu_read_unlock();
}
static void perf_event_task(struct task_struct *task,
@ -3943,7 +3943,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
comm_event->event_id.header.size = sizeof(comm_event->event_id) + size;
rcu_read_lock_sched();
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
perf_event_comm_ctx(&cpuctx->ctx, comm_event);
@ -3956,7 +3956,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
if (ctx)
perf_event_comm_ctx(ctx, comm_event);
}
rcu_read_unlock_sched();
rcu_read_unlock();
}
void perf_event_comm(struct task_struct *task)
@ -4126,7 +4126,7 @@ got_name:
mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;
rcu_read_lock_sched();
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
@ -4142,7 +4142,7 @@ got_name:
vma->vm_flags & VM_EXEC);
}
}
rcu_read_unlock_sched();
rcu_read_unlock();
kfree(buf);
}
@ -5218,10 +5218,11 @@ void perf_pmu_unregister(struct pmu *pmu)
mutex_unlock(&pmus_lock);
/*
* We use the pmu list either under SRCU or preempt_disable,
* synchronize_srcu() implies synchronize_sched() so we're good.
* We dereference the pmu list under both SRCU and regular RCU, so
* synchronize against both of those.
*/
synchronize_srcu(&pmus_srcu);
synchronize_rcu();
free_percpu(pmu->pmu_disable_count);
free_pmu_context(pmu->pmu_cpu_context);