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authorMichal Sojka <[email protected]>2023-03-31 14:55:11 +0200
committerMarc Kleine-Budde <[email protected]>2023-04-05 10:52:00 +0200
commit79e19fa79cb5d5f1b3bf3e3ae24989ccb93c7b7b (patch)
tree3bf6ba506c54594b793de913928857fb72e952f7
parent0145462fc802cd447ef5d029758043c7f15b4b1e (diff)
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/[email protected] v1: https://lore.kernel.org/all/[email protected] https://lore.kernel.org/all/[email protected] Signed-off-by: Michal Sojka <[email protected]> Reported-by: Jakub Jira <[email protected]> Tested-by: Oliver Hartkopp <[email protected]> Acked-by: Oliver Hartkopp <[email protected]> Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Link: https://lore.kernel.org/all/[email protected] Cc: [email protected] Signed-off-by: Marc Kleine-Budde <[email protected]>
-rw-r--r--net/can/isotp.c17
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,