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tty: n_gsm: fix missing corner cases in gsmld_poll()

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[ Upstream commit 7e5b4322cde067e1d0f1bf8f490e93f664a7c843 ]

gsmld_poll() currently fails to handle the following corner cases correctly:
- remote party closed the associated tty

Add the missing checks and map those to EPOLLHUP.
Reorder the checks to group them by their reaction.

Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220707113223.3685-4-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Daniel Starke 2022-07-07 13:32:23 +02:00 committed by Greg Kroah-Hartman
parent ae9bfcbfd7
commit 44913ccfa1
1 changed files with 5 additions and 2 deletions
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7
drivers/tty/n_gsm.c
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@ -2693,12 +2693,15 @@ static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
poll_wait(file, &tty->read_wait, wait);
poll_wait(file, &tty->write_wait, wait);
if (gsm->dead)
mask |= EPOLLHUP;
if (tty_hung_up_p(file))
mask |= EPOLLHUP;
if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
mask |= EPOLLHUP;
if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
mask |= EPOLLOUT | EPOLLWRNORM;
if (gsm->dead)
mask |= EPOLLHUP;
return mask;
}