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tun: honor IOCB_NOWAIT flag 

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@kernel.dk>
Link: https://lore.kernel.org/r/e9451860-96cc-c7c7-47b8-fe42cadd5f4c@kernel.dk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jens Axboe 2020-11-20 07:59:54 -07:00 committed by Jakub Kicinski
parent c5dab0941f
commit 5aac0390a6
1 changed files with 11 additions and 3 deletions
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14
drivers/net/tun.c
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@ -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;