Hello Mikulas,
Any chance you could re-test these v6 patches? It seems you're able to relatively easily trigger the bug on your (pa-risc) environment.. I'd be good to have this series finally acked/merged!
Thanks a lot,
-- Pasi
On Thu, Nov 01, 2018 at 12:24:45AM +0000, Dmitry Safonov wrote:
Hi all,
Here are 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.
Mikulas, can you add your tested-by on this patches set again, please? I tried to reproduce reboot issue on qemu-hppa and even built cross-compiler for pa-risc.. but was unlucky in reproducing.
Thanks, Dima
Changes since v5:
- Better commit tags
- Hopefully fixed issue with reboot on pa-risc with Debian 5
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@arista.com)
- 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@arista.com v2 link: lkml.kernel.org/r/20180903165257.29227-1-dima@arista.com v3 link: lkml.kernel.org/r/20180911014821.26286-1-dima@arista.com v4 link: lkml.kernel.org/r/20180912001702.18522-1-dima@arista.com
Cc: Daniel Axtens dja@axtens.net Cc: Dmitry Vyukov dvyukov@google.com Cc: Mark Rutland mark.rutland@arm.com Cc: Michael Neuling mikey@neuling.org Cc: Mikulas Patocka mpatocka@redhat.com Cc: Nathan March nathan@gt.net Cc: Pasi Kärkkäinen pasik@iki.fi Cc: Peter Hurley peter@hurleysoftware.com Cc: Peter Zijlstra peterz@infradead.org Cc: "Rong, Chen" rong.a.chen@intel.com Cc: Sergey Senozhatsky sergey.senozhatsky.work@gmail.com Cc: Tan Xiaojun tanxiaojun@huawei.com Cc: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp (please, ignore if I Cc'ed you mistakenly)
Dmitry Safonov (6): tty/ldsem: Wake up readers after timed out down_write() tty: Hold tty_ldisc_lock() during tty_reopen() tty: Don't block on IO when ldisc change is pending 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/n_hdlc.c | 4 +-- drivers/tty/n_r3964.c | 2 +- drivers/tty/n_tty.c | 8 +++--- drivers/tty/tty_io.c | 14 ++++++---- drivers/tty/tty_ldisc.c | 16 +++++++++++ drivers/tty/tty_ldsem.c | 62 +++++++++++++++++------------------------ include/linux/tty.h | 7 +++++ 7 files changed, 63 insertions(+), 50 deletions(-)
-- 2.19.1