linux-kernel - [PATCH v3 52/57] perf: Simplify perf_event_init

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Message-ID: <20230612093541.311174114@infradead.org>
Date:   Mon, 12 Jun 2023 11:08:05 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     torvalds@...ux-foundation.org, keescook@...omium.org,
        gregkh@...uxfoundation.org, pbonzini@...hat.com
Cc:     masahiroy@...nel.org, nathan@...nel.org, ndesaulniers@...gle.com,
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Subject: [PATCH v3 52/57] perf: Simplify perf_event_init_context()


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/events/core.c |   29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1450,6 +1450,10 @@ static void perf_unpin_context(struct pe
 	raw_spin_unlock_irqrestore(&ctx->lock, flags);
 }
 
+DEFINE_CLASS(pin_task_ctx, struct perf_event_context *,
+	     if (_T) { perf_unpin_context(_T); put_ctx(_T); },
+	     perf_pin_task_context(task), struct task_struct *task)
+
 /*
  * Update the record of the current time in a context.
  */
@@ -7939,18 +7943,13 @@ static void perf_event_addr_filters_exec
 
 void perf_event_exec(void)
 {
-	struct perf_event_context *ctx;
-
-	ctx = perf_pin_task_context(current);
+	CLASS(pin_task_ctx, ctx)(current);
 	if (!ctx)
 		return;
 
 	perf_event_enable_on_exec(ctx);
 	perf_event_remove_on_exec(ctx);
 	perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true);
-
-	perf_unpin_context(ctx);
-	put_ctx(ctx);
 }
 
 struct remote_output {
@@ -13226,8 +13225,7 @@ inherit_task_group(struct perf_event *ev
  */
 static int perf_event_init_context(struct task_struct *child, u64 clone_flags)
 {
-	struct perf_event_context *child_ctx, *parent_ctx;
-	struct perf_event_context *cloned_ctx;
+	struct perf_event_context *child_ctx, *cloned_ctx;
 	struct perf_event *event;
 	struct task_struct *parent = current;
 	int inherited_all = 1;
@@ -13241,7 +13239,7 @@ static int perf_event_init_context(struc
 	 * If the parent's context is a clone, pin it so it won't get
 	 * swapped under us.
 	 */
-	parent_ctx = perf_pin_task_context(parent);
+	CLASS(pin_task_ctx, parent_ctx)(parent);
 	if (!parent_ctx)
 		return 0;
 
@@ -13256,7 +13254,7 @@ static int perf_event_init_context(struc
 	 * Lock the parent list. No need to lock the child - not PID
 	 * hashed yet and not running, so nobody can access it.
 	 */
-	mutex_lock(&parent_ctx->mutex);
+	guard(mutex)(&parent_ctx->mutex);
 
 	/*
 	 * We dont have to disable NMIs - we are only looking at
@@ -13266,7 +13264,7 @@ static int perf_event_init_context(struc
 		ret = inherit_task_group(event, parent, parent_ctx,
 					 child, clone_flags, &inherited_all);
 		if (ret)
-			goto out_unlock;
+			return ret;
 	}
 
 	/*
@@ -13282,7 +13280,7 @@ static int perf_event_init_context(struc
 		ret = inherit_task_group(event, parent, parent_ctx,
 					 child, clone_flags, &inherited_all);
 		if (ret)
-			goto out_unlock;
+			return ret;
 	}
 
 	raw_spin_lock_irqsave(&parent_ctx->lock, flags);
@@ -13310,13 +13308,8 @@ static int perf_event_init_context(struc
 	}
 
 	raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
-out_unlock:
-	mutex_unlock(&parent_ctx->mutex);
-
-	perf_unpin_context(parent_ctx);
-	put_ctx(parent_ctx);
 
-	return ret;
+	return 0;
 }
 
 /*