can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events
commit 79e19fa7 upstream. 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: e057dd3f ("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> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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