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>
Cc: paulus <paulus@samba.org>
Cc: stephane eranian <eranian@googlemail.com>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Yanmin <yanmin_zhang@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index dae0e2f..13d98d7 100644 (file)
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -1959,9 +1959,7 @@ exit_put:
 /*
  * 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);
@@ -1969,7 +1967,25 @@ __perf_event_init_context(struct perf_event_context *ctx,
        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 *
@@ -2036,22 +2052,22 @@ retry:
        }
 
        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);
@@ -5044,7 +5060,7 @@ 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);
@@ -5866,15 +5882,11 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent,
                 * 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,
@@ -5886,7 +5898,6 @@ inherit_task_group(struct perf_event *event, struct task_struct *parent,
        return ret;
 }
 
-
 /*
  * Initialize the perf_event context in task_struct
  */