linux-kernel - [PATCH v3 27/57] perf: Simplify perf_cgroup

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Message-ID: <20230612093539.452507393@infradead.org>
Date:   Mon, 12 Jun 2023 11:07:40 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     torvalds@...ux-foundation.org, keescook@...omium.org,
        gregkh@...uxfoundation.org, pbonzini@...hat.com
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Subject: [PATCH v3 27/57] perf: Simplify perf_cgroup_connect()

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 include/linux/file.h |    2 +-
 kernel/events/core.c |   19 ++++++++-----------
 2 files changed, 9 insertions(+), 12 deletions(-)

--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -936,22 +936,20 @@ static inline int perf_cgroup_connect(in
 {
 	struct perf_cgroup *cgrp;
 	struct cgroup_subsys_state *css;
-	struct fd f = fdget(fd);
-	int ret = 0;
+	int ret;
 
+	CLASS(fd, f)(fd);
 	if (!f.file)
 		return -EBADF;
 
 	css = css_tryget_online_from_dir(f.file->f_path.dentry,
 					 &perf_event_cgrp_subsys);
-	if (IS_ERR(css)) {
-		ret = PTR_ERR(css);
-		goto out;
-	}
+	if (IS_ERR(css))
+		return PTR_ERR(css);
 
 	ret = perf_cgroup_ensure_storage(event, css);
 	if (ret)
-		goto out;
+		return ret;
 
 	cgrp = container_of(css, struct perf_cgroup, css);
 	event->cgrp = cgrp;
@@ -963,11 +961,10 @@ static inline int perf_cgroup_connect(in
 	 */
 	if (group_leader && group_leader->cgrp != cgrp) {
 		perf_detach_cgroup(event);
-		ret = -EINVAL;
+		return -EINVAL;
 	}
-out:
-	fdput(f);
-	return ret;
+
+	return 0;
 }
 
 static inline void