The following commit has been merged in the linux branch: commit 97ad5a034dcc164269d0b8a5cb3e827b33455c11 Author: Linus Torvalds torvalds@linux-foundation.org Date: Wed Oct 14 09:20:41 2009 -0700
tty: use the new 'flush_delayed_work()' helper to do ldisc flush
This way all flush_to_ldisc work is always done through the workqueues, and we thus have a single point of serialization. It also means that we can avoid calling flush_to_ldisc() entirely if there was no delayed work pending.
[ Side note: using workqueues and keventd as the single way to enter flush_to_ldisc() still doesn't absolutely guarantee that we can't have concurrency: keventd is multithreaded and has a thread per CPU, and while the WORK_STRUCT_PENDING bit guarantees a single work only being on the pending list once, the work might be both pending and _running_ at the same time. Workqueues are not simple. ]
This was also confirmed to fix bugzilla #14388, even without the earlier locking fix and cleanup (commit c8e331419: "tty: Make flush_to_ldisc() locking more robust"). So both commits fix the same bug differently, and either would have worked on its own. But I'm committing them both since they are cleanups independent of each other.
Reported-and-tested-by: Boyan btanastasov@yahoo.co.uk Acked-by: Alan Cox alan@lxorguk.ukuu.org.uk Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
diff --git a/drivers/char/tty_buffer.c b/drivers/char/tty_buffer.c index 0296612..66fa4e1 100644 --- a/drivers/char/tty_buffer.c +++ b/drivers/char/tty_buffer.c @@ -468,7 +468,7 @@ static void flush_to_ldisc(struct work_struct *work) */ void tty_flush_to_ldisc(struct tty_struct *tty) { - flush_to_ldisc(&tty->buf.work.work); + flush_delayed_work(&tty->buf.work); }
/**