linux-kernel - [RFC PATCH 25/27] lift rcu_read_lock() into reverse_path

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Message-Id: <20201004023929.2740074-25-viro@ZenIV.linux.org.uk>
Date:   Sun,  4 Oct 2020 03:39:27 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>
Subject: [RFC PATCH 25/27] lift rcu_read_lock() into reverse_path_check()

From: Al Viro <viro@...iv.linux.org.uk>

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 fs/eventpoll.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 78b8769b72dc..8a7ad752befd 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1257,7 +1257,6 @@ static int reverse_path_check_proc(struct file *file, int depth)
 		return -1;
 
 	/* CTL_DEL can remove links here, but that can't increase our count */
-	rcu_read_lock();
 	hlist_for_each_entry_rcu(epi, &file->f_ep_links, fllink) {
 		struct file *recepient = epi->ep->file;
 		if (WARN_ON(!is_file_epoll(recepient)))
@@ -1269,7 +1268,6 @@ static int reverse_path_check_proc(struct file *file, int depth)
 		if (error != 0)
 			break;
 	}
-	rcu_read_unlock();
 	return error;
 }
 
@@ -1291,7 +1289,9 @@ static int reverse_path_check(void)
 	/* let's call this for all tfiles */
 	list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) {
 		path_count_init();
+		rcu_read_lock();
 		error = reverse_path_check_proc(current_file, 0);
+		rcu_read_unlock();
 		if (error)
 			break;
 	}
-- 
2.11.0