linux-kernel - [PATCH v2] fsnotify: Add missing annotation for fsnotify_finish_user_wait() and for fsnotify_prepare_user

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Date:   Mon, 13 Apr 2020 22:42:40 +0100
From:   Jules Irenge <jbi.octave@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     boqun.feng@...il.com, Jan Kara <jack@...e.cz>,
        Amir Goldstein <amir73il@...il.com>,
        linux-fsdevel@...r.kernel.org (open list:FSNOTIFY: FILESYSTEM
        NOTIFICATION INFRASTRUCTURE)
Subject: [PATCH v2] fsnotify: Add missing annotation for fsnotify_finish_user_wait() and for fsnotify_prepare_user_wait()

Sparse reports warnings at fsnotify_prepare_user_wait()
	and at fsnotify_finish_user_wait()

warning: context imbalance in fsnotify_finish_user_wait()
	- wrong count at exit
warning: context imbalance in fsnotify_prepare_user_wait()
	- unexpected unlock

The root cause is the missing annotation at fsnotify_finish_user_wait()
	and at fsnotify_prepare_user_wait()
fsnotify_prepare_user_wait() has an extra annotation __release()
 that only tell Sparse and not GCC to shutdown the warning

Add the missing  __acquires(&fsnotify_mark_srcu) annotation
Add the missing __releases(&fsnotify_mark_srcu) annotation
Add the __release(&fsnotify_mark_srcu) annotation.

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
changes since v2
-include annotations for fsnotify_prepare_user_wait()

 fs/notify/mark.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 1d96216dffd1..8387937b9d01 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -325,13 +325,16 @@ static void fsnotify_put_mark_wake(struct fsnotify_mark *mark)
 }
 
 bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info)
+	__releases(&fsnotify_mark_srcu)
 {
 	int type;
 
 	fsnotify_foreach_obj_type(type) {
 		/* This can fail if mark is being removed */
-		if (!fsnotify_get_mark_safe(iter_info->marks[type]))
+		if (!fsnotify_get_mark_safe(iter_info->marks[type])) {
+			__release(&fsnotify_mark_srcu);
 			goto fail;
+		}
 	}
 
 	/*
@@ -350,6 +353,7 @@ bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info)
 }
 
 void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info)
+	__acquires(&fsnotify_mark_srcu)
 {
 	int type;
 
-- 
2.24.1