This is a note to let you know that I've just added the patch titled
tun: honor IOCB_NOWAIT flag
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tun-honor-iocb_nowait-flag.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Dec 2 12:09:18 PM CET 2020
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Fri, 20 Nov 2020 07:59:54 -0700
Subject: tun: honor IOCB_NOWAIT flag
From: Jens Axboe <axboe@xxxxxxxxx>
[ Upstream commit 5aac0390a63b8718237a61dd0d24a29201d1c94a ]
tun only checks the file O_NONBLOCK flag, but it should also be checking
the iocb IOCB_NOWAIT flag. Any fops using ->read/write_iter() should check
both, otherwise it breaks users that correctly expect O_NONBLOCK semantics
if IOCB_NOWAIT is set.
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Link: https://lore.kernel.org/r/e9451860-96cc-c7c7-47b8-fe42cadd5f4c@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/tun.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1601,12 +1601,15 @@ static ssize_t tun_chr_write_iter(struct
struct tun_struct *tun = tun_get(file);
struct tun_file *tfile = file->private_data;
ssize_t result;
+ int noblock = 0;
if (!tun)
return -EBADFD;
- result = tun_get_user(tun, tfile, NULL, from,
- file->f_flags & O_NONBLOCK, false);
+ if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+ noblock = 1;
+
+ result = tun_get_user(tun, tfile, NULL, from, noblock, false);
tun_put(tun);
return result;
@@ -1789,10 +1792,15 @@ static ssize_t tun_chr_read_iter(struct
struct tun_file *tfile = file->private_data;
struct tun_struct *tun = __tun_get(tfile);
ssize_t len = iov_iter_count(to), ret;
+ int noblock = 0;
if (!tun)
return -EBADFD;
- ret = tun_do_read(tun, tfile, to, file->f_flags & O_NONBLOCK, NULL);
+
+ if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
+ noblock = 1;
+
+ ret = tun_do_read(tun, tfile, to, noblock, NULL);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
iocb->ki_pos = ret;
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-4.14/tun-honor-iocb_nowait-flag.patch
