netdev - [PATCH] tun: flag the device as supporting FMODE

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Date:   Tue, 7 Mar 2023 20:45:56 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     netdev <netdev@...r.kernel.org>
Cc:     Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH] tun: flag the device as supporting FMODE_NOWAIT

tun already checks for both O_NONBLOCK and IOCB_NOWAIT in its read
and write iter handlers, so it's fully ready for FMODE_NOWAIT. But
for some reason it doesn't set it. Rectify that oversight.

Signed-off-by: Jens Axboe <axboe@...nel.dk>

---

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index ad653b32b2f0..4c7f74904c25 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3463,6 +3463,8 @@ static int tun_chr_open(struct inode *inode, struct file * file)
 
 	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
 
+	/* tun groks IOCB_NOWAIT just fine, mark it as such */
+	file->f_mode |= FMODE_NOWAIT;
 	return 0;
 }
 
-- 
Jens Axboe