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Subject[RFC][PATCH 16/19] perf: Clean up perf_event_context allocation
Unify the two perf_event_context allocation sites.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
kernel/perf_event.c | 41 ++++++++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 15 deletions(-)
Index: linux-2.6/kernel/perf_event.c
===================================================================
--- linux-2.6.orig/kernel/perf_event.c
+++ linux-2.6/kernel/perf_event.c
@@ -1936,9 +1936,7 @@ static struct perf_callchain_entry *perf
/*
* Initialize the perf_event context in a task_struct:
*/
-static void
-__perf_event_init_context(struct perf_event_context *ctx,
- struct task_struct *task)
+static void __perf_event_init_context(struct perf_event_context *ctx)
{
raw_spin_lock_init(&ctx->lock);
mutex_init(&ctx->mutex);
@@ -1946,7 +1944,25 @@ __perf_event_init_context(struct perf_ev
INIT_LIST_HEAD(&ctx->flexible_groups);
INIT_LIST_HEAD(&ctx->event_list);
atomic_set(&ctx->refcount, 1);
- ctx->task = task;
+}
+
+static struct perf_event_context *
+alloc_perf_context(struct pmu *pmu, struct task_struct *task)
+{
+ struct perf_event_context *ctx;
+
+ ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+ if (!ctx)
+ return NULL;
+
+ __perf_event_init_context(ctx);
+ if (task) {
+ ctx->task = task;
+ get_task_struct(task);
+ }
+ ctx->pmu = pmu;
+
+ return ctx;
}

static struct perf_event_context *
@@ -2013,22 +2029,22 @@ find_get_default_context(struct pmu *pmu
}

if (!ctx) {
- ctx = kzalloc(sizeof(struct perf_event_context), GFP_KERNEL);
+ ctx = alloc_perf_context(pmu, task);
err = -ENOMEM;
if (!ctx)
goto errout;
- __perf_event_init_context(ctx, task);
- ctx->pmu = pmu;
+
get_ctx(ctx);
+
if (cmpxchg(&task->perf_event_ctxp, NULL, ctx)) {
/*
* We raced with some other task; use
* the context they set.
*/
+ put_task_struct(task);
kfree(ctx);
goto retry;
}
- get_task_struct(task);
}

put_task_struct(task);
@@ -5021,7 +5037,7 @@ int perf_pmu_register(struct pmu *pmu)
struct perf_cpu_context *cpuctx;

cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
- __perf_event_init_context(&cpuctx->ctx, NULL);
+ __perf_event_init_context(&cpuctx->ctx);
cpuctx->ctx.pmu = pmu;
cpuctx->timer_interval = TICK_NSEC;
hrtimer_init(&cpuctx->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
@@ -5848,15 +5864,11 @@ inherit_task_group(struct perf_event *ev
* child.
*/

- child_ctx = kzalloc(sizeof(struct perf_event_context),
- GFP_KERNEL);
+ child_ctx = alloc_perf_context(event->pmu, child);
if (!child_ctx)
return -ENOMEM;

- __perf_event_init_context(child_ctx, child);
- child_ctx->pmu = event->pmu;
child->perf_event_ctxp = child_ctx;
- get_task_struct(child);
}

ret = inherit_group(event, parent, parent_ctx,
@@ -5868,7 +5880,6 @@ inherit_task_group(struct perf_event *ev
return ret;
}

-
/*
* Initialize the perf_event context in task_struct
*/



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