kernel/git/stable/linux.git/drivers/char/tty_ldisc.c, branch master

TTY: create drivers/tty and move the tty core files there

2010-11-05T15:10:33+00:00

The tty code should be in its own subdirectory and not in the char driver with all of the cruft that is currently there. Based on work done by Arnd Bergmann Acked-by: Arnd Bergmann Cc: Jiri Slaby Cc: Alan Cox Signed-off-by: Greg Kroah-Hartman

tty: remove tty_lock_nested

2010-08-10T20:47:44+00:00

This changes all remaining users of tty_lock_nested to be non-recursive, which lets us kill this function. As a consequence, we won't need to keep the lock count any more, which allows more simplifications later. Signed-off-by: Arnd Bergmann Cc: Alan Cox Signed-off-by: Greg Kroah-Hartman

tty: reorder ldisc locking

2010-08-10T20:47:43+00:00

We need to release the BTM in paste_selection() when sleeping in tty_ldisc_ref_wait to avoid deadlocks with tty_ldisc_enable. In tty_set_ldisc, we now always grab the BTM before taking the ldisc_mutex in order to avoid AB-BA deadlocks between the two. tty_ldisc_halt potentially blocks on a workqueue function that takes the BTM, so we must release the BTM before calling it. Signed-off-by: Arnd Bergmann Cc: Alan Cox Signed-off-by: Greg Kroah-Hartman

tty: replace BKL with a new tty_lock

2010-08-10T20:47:43+00:00

As a preparation for replacing the big kernel lock in the TTY layer, wrap all the callers in new macros tty_lock, tty_lock_nested and tty_unlock. Signed-off-by: Arnd Bergmann Cc: Alan Cox Signed-off-by: Greg Kroah-Hartman

tty: Fix the ldisc hangup race

2010-03-02T22:43:22+00:00

This was noticed by Matthias Urlichs and he proposed a fix. This patch does the fixing a different way to avoid introducing several new race conditions into the code. The problem case is TTY_DRIVER_RESET_TERMIOS = 0. In that case while we abort the ldisc change, the hangup processing has not cleaned up and restarted the ldisc either. We can't restart the ldisc stuff in the set_ldisc as we don't know what the hangup did and may touch stuff we shouldn't as we are no longer supposed to influence the tty at that point in case it has been re-opened before we get rescheduled. Instead do it the simple way. Always re-init the ldisc on the hangup, but use TTY_DRIVER_RESET_TERMIOS to indicate that we should force N_TTY. Signed-off-by: Alan Cox Cc: stable Signed-off-by: Greg Kroah-Hartman

tty: Push the lock down further into the ldisc code

2009-12-11T23:18:08+00:00

Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman

tty: push the BKL down into the handlers a bit

2009-12-11T23:18:08+00:00

Start trying to untangle the remaining BKL mess Updated to fix missing unlock_kernel noted by Dan Carpenter Signed-off-by: Alan "I must be out of my tree" Cox Signed-off-by: Greg Kroah-Hartman

tty: Avoid dropping ldisc_mutex over hangup tty re-initialization

2009-10-04T04:44:21+00:00

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 Reported-by: Heinz Diehl Cc: stable@kernel.org Signed-off-by: Linus Torvalds

tty-ldisc: get rid of tty_ldisc_try_get() helper function

2009-09-19T20:13:10+00:00

Now that the /proc/tty/ldiscs handling doesn't play games with 'struct ldisc' any more, the only remaining user of 'tty_ldisc_try_get()' is 'tty_ldisc_get()' (note the lack of 'try'). And we're actually much better off folding the logic directly into that file, since the 'try' part was always about trying to get the ldisc operations, not the ldisc itself: and making that explicit inside of 'tty_ldisc_get()' clarifies the whole semantics. Signed-off-by: Linus Torvalds Cc: Alan Cox Cc: OGAWA Hirofumi , Tested-by: Sergey Senozhatsky Signed-off-by: Greg Kroah-Hartman

tty-ldisc: make /proc/tty/ldiscs use ldisc_ops instead of ldiscs

2009-09-19T20:13:10+00:00

The /proc/tty/ldiscs file is totally and utterly un-interested in the "struct tty_ldisc" structures, and only cares about the underlying ldisc operations. So don't make it create a dummy 'struct ldisc' only to get a pointer to the operations, and then destroy it. Instead, we split up the function 'tty_ldisc_try_get()', and create a 'get_ldops()' helper that just looks up the ldisc operations based on the ldisc number. That makes the code simpler to read (smaller and more well-defined helper functions), and allows the /proc functions to avoid creating that useless dummy only to immediately free it again. Signed-off-by: Linus Torvalds Tested-by: Sergey Senozhatsky Cc: Alan Cox Cc: OGAWA Hirofumi Signed-off-by: Greg Kroah-Hartman