https://github.com/torvalds/linux
Revision 0b5759c654e74c8dc317ea2c6b3a7476160f688a authored by Linus Torvalds on 04 October 2009, 04:44:21 UTC, committed by Linus Torvalds on 04 October 2009, 04:44:21 UTC
A couple of people have hit the WARN_ON() in drivers/char/tty_io.c, tty_open() that is unhappy about seeing the tty line discipline go away during the tty hangup. See for example http://bugzilla.kernel.org/show_bug.cgi?id=14255 and the reason is that we do the tty_ldisc_halt() outside the ldisc_mutex in order to be able to flush the scheduled work without a deadlock with vhangup_work. However, it turns out that we can solve this particular case by - using "cancel_delayed_work_sync()" in tty_ldisc_halt(), which waits for just the particular work, rather than synchronizing with any random outstanding pending work. This won't deadlock, since the buf.work we synchronize with doesn't care about the ldisc_mutex, it just flushes the tty ldisc buffers. - realize that for this particular case, we don't need to wait for any hangup work, because we are inside the hangup codepaths ourselves. so as a result we can just drop the flush_scheduled_work() entirely, and then move the tty_ldisc_halt() call to inside the mutex. That way we never expose the partially torn down ldisc state to tty_open(), and hold the ldisc_mutex over the whole sequence. Reported-by: Ingo Molnar <mingo@elte.hu> Reported-by: Heinz Diehl <htd@fancy-poultry.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent f0a221e
Tip revision: 0b5759c654e74c8dc317ea2c6b3a7476160f688a authored by Linus Torvalds on 04 October 2009, 04:44:21 UTC
tty: Avoid dropping ldisc_mutex over hangup tty re-initialization
tty: Avoid dropping ldisc_mutex over hangup tty re-initialization
Tip revision: 0b5759c
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arch | ||
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crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
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.gitignore | -rw-r--r-- | 952 bytes |
.mailmap | -rw-r--r-- | 3.9 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 91.8 KB |
Kbuild | -rw-r--r-- | 2.4 KB |
MAINTAINERS | -rw-r--r-- | 154.0 KB |
Makefile | -rw-r--r-- | 55.4 KB |
README | -rw-r--r-- | 17.0 KB |
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