Hi all, Three fixes that worth to have in the @stable, as we've hit them on v4.9 stable. And for linux-next - adding lockdep asserts for line discipline changing code, verifying that write ldisc sem will be held forthwith. The last patch is optional and probably, timeout can be dropped for read_lock(). I'll do it if everyone agrees. Rong Chen, could you kindly re-run this version to see if the lockup from v1 still happens? I wasn't able to reproduce it.. Thanks, Dima Changes since v2: - Added reviewed-by tags - Hopefully, fixed reported by 0-day issue. - Added optional fix for wait_readers decrement Changes since v1: - Added tested-by/reported-by tags - Dropped 3/4 (locking tty pair for lockdep sake), Because of that - not adding lockdep_assert_held() in tty_ldisc_open() - Added 4/4 cleanup to inc tty->count only on success of tty_ldisc_reinit() - lock ldisc without (5*HZ) timeout in tty_reopen() v1 link: lkml.kernel.org/r/<20180829022353.23568-1-dima@xxxxxxxxxx> Huuge cc list: Cc: Daniel Axtens <dja@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Michael Neuling <mikey@xxxxxxxxxxx> Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx> Cc: Nathan March <nathan@xxxxxx> Cc: Pasi Kärkkäinen <pasik@xxxxxx> Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> Cc: "Rong, Chen" <rong.a.chen@xxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx> Cc: Tan Xiaojun <tanxiaojun@xxxxxxxxxx> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> (please, ignore if I Cc'ed you mistakenly) Dmitry Safonov (6): tty: Drop tty->count on tty_reopen() failure tty/ldsem: Update waiter->task before waking up reader tty: Hold tty_ldisc_lock() during tty_reopen() tty/lockdep: Add ldisc_sem asserts tty: Simplify tty->count math in tty_reopen() tty/ldsem: Decrement wait_readers on timeouted down_read() drivers/tty/tty_io.c | 12 ++++++++---- drivers/tty/tty_ldisc.c | 5 +++++ drivers/tty/tty_ldsem.c | 5 ++++- 3 files changed, 17 insertions(+), 5 deletions(-) -- 2.13.6
