[PATCH v2 2/2] perf/core: Remove perf_cpu_context::unique_pmu

David Carrillo-Cisneros
2017-01-18T19:26:04Z

cpuctx->unique_pmu was originally introduced as a way to identify cpuctxs
with shared pmus in order to avoid visiting the same cpuctx more than once
in a for_each_pmu loop.

cpuctx->unique_pmu == cpuctx->pmu in non-software task contexts since they
have only one pmu per cpuctx. Since perf_pmu_sched_task is only called in
hw contexts, this patch replaces cpuctx->unique_pmu by cpuctx->pmu in it.

The change above, together with the previous patch in this series, removed
the remaining uses of cpuctx->unique_pmu, so we remove it altogether.

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
include/linux/perf_event.h | 1 -
kernel/events/core.c | 31 +------------------------------
2 files changed, 1 insertion(+), 31 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 10d223572855..4f8a1f681aac 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -785,7 +785,6 @@ struct perf_cpu_context {
ktime_t hrtimer_interval;
unsigned int hrtimer_active;

- struct pmu *unique_pmu;
#ifdef CONFIG_CGROUP_PERF
struct perf_cgroup *cgrp;
struct list_head cgrp_cpuctx_entry;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5f5b760bc25b..65b706d25422 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2883,7 +2883,7 @@ static void perf_pmu_sched_task(struct task_struct *prev,
return;

list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {
- pmu = cpuctx->unique_pmu; /* software PMUs will not have sched_task */
+ pmu = cpuctx->ctx.pmu; /* software PMUs will not have sched_task */

if (WARN_ON_ONCE(!pmu->sched_task))
continue;
@@ -8572,37 +8572,10 @@ static struct perf_cpu_context __percpu *find_pmu_context(int ctxn)
return NULL;
}

-static void update_pmu_context(struct pmu *pmu, struct pmu *old_pmu)
-{
- int cpu;
-
- for_each_possible_cpu(cpu) {
- struct perf_cpu_context *cpuctx;
-
- cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-
- if (cpuctx->unique_pmu == old_pmu)
- cpuctx->unique_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(i, &pmus, entry) {
- if (i->pmu_cpu_context == pmu->pmu_cpu_context) {
- update_pmu_context(i, pmu);
- goto out;
- }
- }
-
free_percpu(pmu->pmu_cpu_context);
-out:
mutex_unlock(&pmus_lock);
}

@@ -8806,8 +8779,6 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
cpuctx->ctx.pmu = pmu;

__perf_mux_hrtimer_init(cpuctx, cpu);
-
- cpuctx->unique_pmu = pmu;
}

got_cpu_context:
--
2.11.0.483.g087da7b7c-goog