diff options
| author | Michal Sojka <michal.sojka@cvut.cz> | 2023-03-31 14:55:11 +0200 |
|---|---|---|
| committer | Marc Kleine-Budde <mkl@pengutronix.de> | 2023-04-05 10:52:00 +0200 |
| commit | 79e19fa79cb5d5f1b3bf3e3ae24989ccb93c7b7b (patch) | |
| tree | 3bf6ba506c54594b793de913928857fb72e952f7 /net/can | |
| parent | 0145462fc802cd447ef5d029758043c7f15b4b1e (diff) | |
| download | lwn-79e19fa79cb5d5f1b3bf3e3ae24989ccb93c7b7b.tar.gz lwn-79e19fa79cb5d5f1b3bf3e3ae24989ccb93c7b7b.zip | |
can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events
When using select()/poll()/epoll() with a non-blocking ISOTP socket to
wait for when non-blocking write is possible, a false EPOLLOUT event
is sometimes returned. This can happen at least after sending a
message which must be split to multiple CAN frames.
The reason is that isotp_sendmsg() returns -EAGAIN when tx.state is
not equal to ISOTP_IDLE and this behavior is not reflected in
datagram_poll(), which is used in isotp_ops.
This is fixed by introducing ISOTP-specific poll function, which
suppresses the EPOLLOUT events in that case.
v2: https://lore.kernel.org/all/20230302092812.320643-1-michal.sojka@cvut.cz
v1: https://lore.kernel.org/all/20230224010659.48420-1-michal.sojka@cvut.cz
https://lore.kernel.org/all/b53a04a2-ba1f-3858-84c1-d3eb3301ae15@hartkopp.net
Signed-off-by: Michal Sojka <michal.sojka@cvut.cz>
Reported-by: Jakub Jira <jirajak2@fel.cvut.cz>
Tested-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol")
Link: https://lore.kernel.org/all/20230331125511.372783-1-michal.sojka@cvut.cz
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Diffstat (limited to 'net/can')
| -rw-r--r-- | net/can/isotp.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/net/can/isotp.c b/net/can/isotp.c index 47c2ebad10ed..281b7766c54e 100644 --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -1608,6 +1608,21 @@ static int isotp_init(struct sock *sk) return 0; } +static __poll_t isotp_poll(struct file *file, struct socket *sock, poll_table *wait) +{ + struct sock *sk = sock->sk; + struct isotp_sock *so = isotp_sk(sk); + + __poll_t mask = datagram_poll(file, sock, wait); + poll_wait(file, &so->wait, wait); + + /* Check for false positives due to TX state */ + if ((mask & EPOLLWRNORM) && (so->tx.state != ISOTP_IDLE)) + mask &= ~(EPOLLOUT | EPOLLWRNORM); + + return mask; +} + static int isotp_sock_no_ioctlcmd(struct socket *sock, unsigned int cmd, unsigned long arg) { @@ -1623,7 +1638,7 @@ static const struct proto_ops isotp_ops = { .socketpair = sock_no_socketpair, .accept = sock_no_accept, .getname = isotp_getname, - .poll = datagram_poll, + .poll = isotp_poll, .ioctl = isotp_sock_no_ioctlcmd, .gettstamp = sock_gettstamp, .listen = sock_no_listen, |