[tip:perf/urgent] perf: Fix duplicate events with multiple-pmu vs software events

tip-bot for Peter Zijlstra
2010-12-08T20:40:33Z

Commit-ID: 5167695753c63444a9e6cbbef136200a16c7a225
Gitweb: http://git.kernel.org/tip/5167695753c63444a9e6cbbef136200a16c7a225
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Tue, 7 Dec 2010 14:18:20 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 8 Dec 2010 20:14:08 +0100

perf: Fix duplicate events with multiple-pmu vs software events

Because the multi-pmu bits can share contexts between struct pmu
instances we could get duplicate events by iterating the pmu list.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/perf_event.h | 1 +
kernel/perf_event.c | 35 +++++++++++++++++++++++++++++------
2 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index de2c417..4f1279e 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -887,6 +887,7 @@ struct perf_cpu_context {
int exclusive;
struct list_head rotation_list;
int jiffies_interval;
+ struct pmu *active_pmu;
};

struct perf_output_handle {
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index eac7e33..7b87017 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -3824,6 +3824,8 @@ static void perf_event_task_event(struct perf_task_event *task_event)
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+ if (cpuctx->active_pmu != pmu)
+ goto next;
perf_event_task_ctx(&cpuctx->ctx, task_event);

ctx = task_event->task_ctx;
@@ -3959,6 +3961,8 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event)
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+ if (cpuctx->active_pmu != pmu)
+ goto next;
perf_event_comm_ctx(&cpuctx->ctx, comm_event);

ctxn = pmu->task_ctx_nr;
@@ -4144,6 +4148,8 @@ got_name:
rcu_read_lock();
list_for_each_entry_rcu(pmu, &pmus, entry) {
cpuctx = get_cpu_ptr(pmu->pmu_cpu_context);
+ if (cpuctx->active_pmu != pmu)
+ goto next;
perf_event_mmap_ctx(&cpuctx->ctx, mmap_event,
vma->vm_flags & VM_EXEC);

@@ -5145,20 +5151,36 @@ static void *find_pmu_context(int ctxn)
return NULL;
}

-static void free_pmu_context(void * __percpu cpu_context)
+static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
{
- struct pmu *pmu;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct perf_cpu_context *cpuctx;
+
+ cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+
+ if (cpuctx->active_pmu == old_pmu)
+ cpuctx->active_pmu = pmu;
+ }
+}
+
+static void free_pmu_context(struct pmu *pmu)
+{
+ struct pmu *i;

mutex_lock(&pmus_lock);
/*
* Like a real lame refcount.
*/
- list_for_each_entry(pmu, &pmus, entry) {
- if (pmu->pmu_cpu_context == cpu_context)
+ list_for_each_entry(i, &pmus, entry) {
+ if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
+ update_pmu_context(i, pmu);
goto out;
+ }
}

- free_percpu(cpu_context);
+ free_percpu(pmu->pmu_cpu_context);
out:
mutex_unlock(&pmus_lock);
}
@@ -5190,6 +5212,7 @@ int perf_pmu_register(struct pmu *pmu)
cpuctx->ctx.pmu = pmu;
cpuctx->jiffies_interval = 1;
INIT_LIST_HEAD(&cpuctx->rotation_list);
+ cpuctx->active_pmu = pmu;
}

got_cpu_context:
@@ -5241,7 +5264,7 @@ void perf_pmu_unregister(struct pmu *pmu)
synchronize_rcu();

free_percpu(pmu->pmu_disable_count);
- free_pmu_context(pmu->pmu_cpu_context);
+ free_pmu_context(pmu);
}

struct pmu *perf_init_event(struct perf_event *event)