On Tue, 18 Sep 2018, Dmitry Safonov wrote: > Hi all, > > Three fixes that worth to have in the @stable, as they were hit by > different people, including Arista 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 an optional and probably, timeout can be dropped for > read_lock(). I'll do it if everyone agrees. > (Or as per discussion with Peter in v3, just convert ldisc to > a regular rwsem). > > Thanks, > Dima I confirm that this patch series fixes the crash for me. Tested-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > Changes since v4: > - back to lock ldisc with (5*HZ) timeout in tty_reopen() > (LKP report link: lkml.kernel.org/r/<1536940609.3185.29.camel@xxxxxxxxxx>) > - reordered 3/7 with 2/7 for LKP robot > > Changes since v3: > - Added tested-by Mark Rutland (thanks!) > - Dropped patch with smp_wmb() - wrong idea > - lockdep_assert_held() should be actually lockdep_assert_held_exclusive() > - Described why tty_ldisc_open() can be called without ldisc_sem held > for pty slave end (o_tty). > - Added Peter's patch for dropping self-made lockdep annotations > - Fix for a reader(s) of ldisc semaphore waiting for an active reader(s) > > 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> > v2 link: lkml.kernel.org/r/<20180903165257.29227-1-dima@xxxxxxxxxx> > v3 link: lkml.kernel.org/r/<20180911014821.26286-1-dima@xxxxxxxxxx> > v4 link: lkml.kernel.org/r/<20180912001702.18522-1-dima@xxxxxxxxxx> > > Cc: Daniel Axtens <dja@xxxxxxxxxx> > Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Cc: Mark Rutland <mark.rutland@xxxxxxx> > 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: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > 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: Wake up readers after timed out down_write() > tty: Hold tty_ldisc_lock() during tty_reopen() > tty: Simplify tty->count math in tty_reopen() > tty/ldsem: Add lockdep asserts for ldisc_sem > tty/ldsem: Decrement wait_readers on timeouted down_read() > > Peter Zijlstra (1): > tty/ldsem: Convert to regular lockdep annotations > > drivers/tty/tty_io.c | 13 ++++++++--- > drivers/tty/tty_ldisc.c | 9 +++++++ > drivers/tty/tty_ldsem.c | 62 ++++++++++++++++++++----------------------------- > 3 files changed, 44 insertions(+), 40 deletions(-) > > -- > 2.13.6 >
