From: Alan Cox Date: Tue, 16 Jun 2009 16:01:33 +0000 (+0100) Subject: tty: fix sanity check X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1aa4bed82a684308f54bf782cffaecd4b1dc3cf4;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git tty: fix sanity check The WARN_ON() that was added to tty_reopen can be triggered in the specific case of a hangup occurring during a re-open of a tty which is not in the middle of being otherwise closed. In that case however the WARN() is bogus as we don't hold the neccessary locks to make a correct decision. The case we should be checking is "if the ldisc is not changing and reopen is occuring". We could drop the WARN_ON but for the moment the debug is more valuable even if it means taking a mutex as it will find any other cases. Signed-off-by: Alan Cox Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 939e198d7670..a3afa0c387cd 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1263,7 +1263,9 @@ static int tty_reopen(struct tty_struct *tty) tty->count++; tty->driver = driver; /* N.B. why do this every time?? */ + mutex_lock(&tty->ldisc_mutex); WARN_ON(!test_bit(TTY_LDISC, &tty->flags)); + mutex_unlock(&tty->ldisc_mutex); return 0; }