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* [PATCH] tun: honor IOCB_NOWAIT flag
@ 2020-11-20 14:59 Jens Axboe
  2020-11-21 23:19 ` Jakub Kicinski
  0 siblings, 1 reply; 3+ messages in thread
From: Jens Axboe @ 2020-11-20 14:59 UTC (permalink / raw)
  To: Networking; +Cc: Jakub Kicinski

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.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

Had a bug report on io_uring, and it's due to tun not honoring
IOCB_NOWAIT. Let's get this fixed.

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index be69d272052f..cd06cae76035 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1961,12 +1961,15 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct tun_file *tfile = file->private_data;
 	struct tun_struct *tun = tun_get(tfile);
 	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;
@@ -2185,10 +2188,15 @@ static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	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;

-- 
Jens Axboe


^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] tun: honor IOCB_NOWAIT flag
  2020-11-20 14:59 [PATCH] tun: honor IOCB_NOWAIT flag Jens Axboe
@ 2020-11-21 23:19 ` Jakub Kicinski
  0 siblings, 0 replies; 3+ messages in thread
From: Jakub Kicinski @ 2020-11-21 23:19 UTC (permalink / raw)
  To: Jens Axboe; +Cc: Networking

On Fri, 20 Nov 2020 07:59:54 -0700 Jens Axboe wrote:
> 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.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

Applied, thanks!

^ permalink raw reply	[flat|nested] 3+ messages in thread
* [PATCH] tun: honor IOCB_NOWAIT flag
@ 2020-11-20 14:59 Jens Axboe
  0 siblings, 0 replies; 3+ messages in thread
From: Jens Axboe @ 2020-11-20 14:59 UTC (permalink / raw)
  To: Networking; +Cc: Jakub Kicinski

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.

Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

Had a bug report on io_uring, and it's due to tun not honoring
IOCB_NOWAIT. Let's get this fixed.

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index be69d272052f..cd06cae76035 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1961,12 +1961,15 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct tun_file *tfile = file->private_data;
 	struct tun_struct *tun = tun_get(tfile);
 	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;
@@ -2185,10 +2188,15 @@ static ssize_t tun_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	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;

-- 
Jens Axboe


^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-11-21 23:40 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2020-11-20 14:59 [PATCH] tun: honor IOCB_NOWAIT flag Jens Axboe
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2020-11-20 14:59 Jens Axboe

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