linux-stable/net
Michal Sojka 9c5df2f14e can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events
commit 79e19fa79c 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: e057dd3fc2 ("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>
2023-04-20 12:10:23 +02:00
..
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9p
802
8021q
appletalk
atm
ax25
batman-adv
bluetooth
bpf
bpfilter
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can can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events 2023-04-20 12:10:23 +02:00
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