[PATCH v3 49/57] perf: Simplify perf_event_alloc()

[Peter Zijlstra]

Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
---
 kernel/events/core.c |   47 ++++++++++++++++++-----------------------------
 1 file changed, 18 insertions(+), 29 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5148,6 +5148,8 @@ static void __free_event(struct perf_eve
 	call_rcu(&event->rcu_head, free_event_rcu);
 }
 
+DEFINE_FREE(__free_event, struct perf_event *, if (_T) __free_event(_T))
+
 /* vs perf_event_alloc() success */
 static void _free_event(struct perf_event *event)
 {
@@ -11694,7 +11696,6 @@ perf_event_alloc(struct perf_event_attr
 		 void *context, int cgroup_fd)
 {
 	struct pmu *pmu;
-	struct perf_event *event;
 	struct hw_perf_event *hwc;
 	long err = -EINVAL;
 	int node;
@@ -11709,8 +11710,8 @@ perf_event_alloc(struct perf_event_attr
 	}
 
 	node = (cpu >= 0) ? cpu_to_node(cpu) : -1;
-	event = kmem_cache_alloc_node(perf_event_cache, GFP_KERNEL | __GFP_ZERO,
-				      node);
+	struct perf_event *event __free(__free_event) =
+		kmem_cache_alloc_node(perf_event_cache, GFP_KERNEL | __GFP_ZERO, node);
 	if (!event)
 		return ERR_PTR(-ENOMEM);
 
@@ -11815,51 +11816,43 @@ perf_event_alloc(struct perf_event_attr
 	 * See perf_output_read().
 	 */
 	if (attr->inherit && (attr->sample_type & PERF_SAMPLE_READ))
-		goto err;
+		return ERR_PTR(-EINVAL);
 
 	if (!has_branch_stack(event))
 		event->attr.branch_sample_type = 0;
 
 	pmu = perf_init_event(event);
-	if (IS_ERR(pmu)) {
-		err = PTR_ERR(pmu);
-		goto err;
-	}
+	if (IS_ERR(pmu))
+		return (void*)pmu;
 
 	/*
 	 * Disallow uncore-task events. Similarly, disallow uncore-cgroup
 	 * events (they don't make sense as the cgroup will be different
 	 * on other CPUs in the uncore mask).
 	 */
-	if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) {
-		err = -EINVAL;
-		goto err;
-	}
+	if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1))
+		return ERR_PTR(-EINVAL);
 
 	if (event->attr.aux_output &&
-	    !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
-		err = -EOPNOTSUPP;
-		goto err;
-	}
+	    !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT))
+		return ERR_PTR(-EOPNOTSUPP);
 
 	if (cgroup_fd != -1) {
 		err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader);
 		if (err)
-			goto err;
+			return ERR_PTR(err);
 	}
 
 	err = exclusive_event_init(event);
 	if (err)
-		goto err;
+		return ERR_PTR(err);
 
 	if (has_addr_filter(event)) {
 		event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters,
 						    sizeof(struct perf_addr_filter_range),
 						    GFP_KERNEL);
-		if (!event->addr_filter_ranges) {
-			err = -ENOMEM;
-			goto err;
-		}
+		if (!event->addr_filter_ranges)
+			return ERR_PTR(-ENOMEM);
 
 		/*
 		 * Clone the parent's vma offsets: they are valid until exec()
@@ -11883,22 +11876,18 @@ perf_event_alloc(struct perf_event_attr
 		if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
 			err = get_callchain_buffers(attr->sample_max_stack);
 			if (err)
-				goto err;
+				return ERR_PTR(err);
 		}
 	}
 
 	err = security_perf_event_alloc(event);
 	if (err)
-		goto err;
+		return ERR_PTR(err);
 
 	/* symmetric to unaccount_event() in _free_event() */
 	account_event(event);
 
-	return event;
-
-err:
-	__free_event(event);
-	return ERR_PTR(err);
+	return_ptr(event);
 }
 
 static int perf_copy_attr(struct perf_event_attr __user *uattr,