diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2010-06-18 14:58:07 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-10 13:47:44 -0700 |
| commit | 11dbf203922dc70a340417c895c95fb96f6b7068 (patch) | |
| tree | 7c79b79c74a184a7d67d3f54af4e37dee930d11e | |
| parent | a0821df6e57c8af0053963d0d08c8d5198ea077d (diff) | |
| download | linux-11dbf203922dc70a340417c895c95fb96f6b7068.tar.gz linux-11dbf203922dc70a340417c895c95fb96f6b7068.tar.bz2 linux-11dbf203922dc70a340417c895c95fb96f6b7068.zip | |
tty: avoid recursive BTM in pty_close
When the console has been redirected, a hangup of the tty
will cause tty_release to be called under the big tty_mutex,
which leads to a deadlock because hangup is also called
under the BTM.
This moves the BTM deeper into the tty_hangup function so
we can close the redirected tty without holding the BTM.
In case of pty, we now need to drop the BTM before
calling tty_vhangup.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/char/pty.c | 4 | ||||
| -rw-r--r-- | drivers/char/tty_io.c | 24 |
2 files changed, 15 insertions, 13 deletions
diff --git a/drivers/char/pty.c b/drivers/char/pty.c index f2d7a76fab54..ad46eae1f9bb 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -62,7 +62,9 @@ static void pty_close(struct tty_struct *tty, struct file *filp) if (tty->driver == ptm_driver) devpts_pty_kill(tty->link); #endif - tty_vhangup_locked(tty->link); + tty_unlock(); + tty_vhangup(tty->link); + tty_lock(); } } diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index dcf7d368639e..4c4030c12d3a 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -471,7 +471,7 @@ void tty_wakeup(struct tty_struct *tty) EXPORT_SYMBOL_GPL(tty_wakeup); /** - * do_tty_hangup - actual handler for hangup events + * __tty_hangup - actual handler for hangup events * @work: tty device * * This can be called by the "eventd" kernel thread. That is process @@ -492,7 +492,7 @@ EXPORT_SYMBOL_GPL(tty_wakeup); * tasklist_lock to walk task list for hangup event * ->siglock to protect ->signal/->sighand */ -void tty_vhangup_locked(struct tty_struct *tty) +void __tty_hangup(struct tty_struct *tty) { struct file *cons_filp = NULL; struct file *filp, *f = NULL; @@ -512,10 +512,12 @@ void tty_vhangup_locked(struct tty_struct *tty) } spin_unlock(&redirect_lock); + tty_lock(); + /* inuse_filps is protected by the single tty lock, this really needs to change if we want to flush the workqueue with the lock held */ - check_tty_count(tty, "do_tty_hangup"); + check_tty_count(tty, "tty_hangup"); file_list_lock(); /* This breaks for file handles being sent over AF_UNIX sockets ? */ @@ -594,6 +596,9 @@ void tty_vhangup_locked(struct tty_struct *tty) */ set_bit(TTY_HUPPED, &tty->flags); tty_ldisc_enable(tty); + + tty_unlock(); + if (f) fput(f); } @@ -603,9 +608,7 @@ static void do_tty_hangup(struct work_struct *work) struct tty_struct *tty = container_of(work, struct tty_struct, hangup_work); - tty_lock(); - tty_vhangup_locked(tty); - tty_unlock(); + __tty_hangup(tty); } /** @@ -643,13 +646,12 @@ void tty_vhangup(struct tty_struct *tty) printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); #endif - tty_lock(); - tty_vhangup_locked(tty); - tty_unlock(); + __tty_hangup(tty); } EXPORT_SYMBOL(tty_vhangup); + /** * tty_vhangup_self - process vhangup for own ctty * @@ -727,10 +729,8 @@ void disassociate_ctty(int on_exit) if (tty) { tty_pgrp = get_pid(tty->pgrp); if (on_exit) { - tty_lock(); if (tty->driver->type != TTY_DRIVER_TYPE_PTY) - tty_vhangup_locked(tty); - tty_unlock(); + tty_vhangup(tty); } tty_kref_put(tty); } else if (on_exit) { |