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>

1 files changed, 26 insertions, 15 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index dae0e2f3029..13d98d75634 100644
--- 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
  */