linux-kernel - [PATCH] fs: Add an explicit might

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Message-Id: <20200527141753.101163-1-kpsingh@chromium.org>
Date:   Wed, 27 May 2020 16:17:53 +0200
From:   KP Singh <kpsingh@...omium.org>
To:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Brendan Jackman <jackmanb@...omium.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@...radead.org>
Subject: [PATCH] fs: Add an explicit might_sleep() to iput

From: KP Singh <kpsingh@...gle.com>

It is currently mentioned in the comments to the function that iput
might sleep when the inode is destroyed. Have it call might_sleep, as
dput already does.

Adding an explicity might_sleep() would help in quickly realizing that
iput is called from a place where sleeping is not allowed when
CONFIG_DEBUG_ATOMIC_SLEEP is enabled as noticed in the dicussion:

  https://lore.kernel.org/bpf/20200527021111.GA197666@google.com/

Signed-off-by: KP Singh <kpsingh@...gle.com>
Reviewed-by: Brendan Jackman <jackmanb@...omium.org>
---
 fs/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/inode.c b/fs/inode.c
index cc6e701b7e5d..f55e72e76266 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1583,6 +1583,7 @@ static void iput_final(struct inode *inode)
  */
 void iput(struct inode *inode)
 {
+	might_sleep();
 	if (!inode)
 		return;
 	BUG_ON(inode->i_state & I_CLEAR);
-- 
2.27.0.rc0.183.gde8f92d652-goog