diff options
author | Arnd Bergmann <arnd@arndb.de> | 2010-06-18 08:58:07 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-08-10 16:47:44 -0400 |
commit | 11dbf203922dc70a340417c895c95fb96f6b7068 (patch) | |
tree | 7c79b79c74a184a7d67d3f54af4e37dee930d11e /drivers/char | |
parent | a0821df6e57c8af0053963d0d08c8d5198ea077d (diff) |
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>
Diffstat (limited to 'drivers/char')
-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) | |||
62 | if (tty->driver == ptm_driver) | 62 | if (tty->driver == ptm_driver) |
63 | devpts_pty_kill(tty->link); | 63 | devpts_pty_kill(tty->link); |
64 | #endif | 64 | #endif |
65 | tty_vhangup_locked(tty->link); | 65 | tty_unlock(); |
66 | tty_vhangup(tty->link); | ||
67 | tty_lock(); | ||
66 | } | 68 | } |
67 | } | 69 | } |
68 | 70 | ||
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) | |||
471 | EXPORT_SYMBOL_GPL(tty_wakeup); | 471 | EXPORT_SYMBOL_GPL(tty_wakeup); |
472 | 472 | ||
473 | /** | 473 | /** |
474 | * do_tty_hangup - actual handler for hangup events | 474 | * __tty_hangup - actual handler for hangup events |
475 | * @work: tty device | 475 | * @work: tty device |
476 | * | 476 | * |
477 | * This can be called by the "eventd" kernel thread. That is process | 477 | * This can be called by the "eventd" kernel thread. That is process |
@@ -492,7 +492,7 @@ EXPORT_SYMBOL_GPL(tty_wakeup); | |||
492 | * tasklist_lock to walk task list for hangup event | 492 | * tasklist_lock to walk task list for hangup event |
493 | * ->siglock to protect ->signal/->sighand | 493 | * ->siglock to protect ->signal/->sighand |
494 | */ | 494 | */ |
495 | void tty_vhangup_locked(struct tty_struct *tty) | 495 | void __tty_hangup(struct tty_struct *tty) |
496 | { | 496 | { |
497 | struct file *cons_filp = NULL; | 497 | struct file *cons_filp = NULL; |
498 | struct file *filp, *f = NULL; | 498 | struct file *filp, *f = NULL; |
@@ -512,10 +512,12 @@ void tty_vhangup_locked(struct tty_struct *tty) | |||
512 | } | 512 | } |
513 | spin_unlock(&redirect_lock); | 513 | spin_unlock(&redirect_lock); |
514 | 514 | ||
515 | tty_lock(); | ||
516 | |||
515 | /* inuse_filps is protected by the single tty lock, | 517 | /* inuse_filps is protected by the single tty lock, |
516 | this really needs to change if we want to flush the | 518 | this really needs to change if we want to flush the |
517 | workqueue with the lock held */ | 519 | workqueue with the lock held */ |
518 | check_tty_count(tty, "do_tty_hangup"); | 520 | check_tty_count(tty, "tty_hangup"); |
519 | 521 | ||
520 | file_list_lock(); | 522 | file_list_lock(); |
521 | /* This breaks for file handles being sent over AF_UNIX sockets ? */ | 523 | /* This breaks for file handles being sent over AF_UNIX sockets ? */ |
@@ -594,6 +596,9 @@ void tty_vhangup_locked(struct tty_struct *tty) | |||
594 | */ | 596 | */ |
595 | set_bit(TTY_HUPPED, &tty->flags); | 597 | set_bit(TTY_HUPPED, &tty->flags); |
596 | tty_ldisc_enable(tty); | 598 | tty_ldisc_enable(tty); |
599 | |||
600 | tty_unlock(); | ||
601 | |||
597 | if (f) | 602 | if (f) |
598 | fput(f); | 603 | fput(f); |
599 | } | 604 | } |
@@ -603,9 +608,7 @@ static void do_tty_hangup(struct work_struct *work) | |||
603 | struct tty_struct *tty = | 608 | struct tty_struct *tty = |
604 | container_of(work, struct tty_struct, hangup_work); | 609 | container_of(work, struct tty_struct, hangup_work); |
605 | 610 | ||
606 | tty_lock(); | 611 | __tty_hangup(tty); |
607 | tty_vhangup_locked(tty); | ||
608 | tty_unlock(); | ||
609 | } | 612 | } |
610 | 613 | ||
611 | /** | 614 | /** |
@@ -643,13 +646,12 @@ void tty_vhangup(struct tty_struct *tty) | |||
643 | 646 | ||
644 | printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); | 647 | printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf)); |
645 | #endif | 648 | #endif |
646 | tty_lock(); | 649 | __tty_hangup(tty); |
647 | tty_vhangup_locked(tty); | ||
648 | tty_unlock(); | ||
649 | } | 650 | } |
650 | 651 | ||
651 | EXPORT_SYMBOL(tty_vhangup); | 652 | EXPORT_SYMBOL(tty_vhangup); |
652 | 653 | ||
654 | |||
653 | /** | 655 | /** |
654 | * tty_vhangup_self - process vhangup for own ctty | 656 | * tty_vhangup_self - process vhangup for own ctty |
655 | * | 657 | * |
@@ -727,10 +729,8 @@ void disassociate_ctty(int on_exit) | |||
727 | if (tty) { | 729 | if (tty) { |
728 | tty_pgrp = get_pid(tty->pgrp); | 730 | tty_pgrp = get_pid(tty->pgrp); |
729 | if (on_exit) { | 731 | if (on_exit) { |
730 | tty_lock(); | ||
731 | if (tty->driver->type != TTY_DRIVER_TYPE_PTY) | 732 | if (tty->driver->type != TTY_DRIVER_TYPE_PTY) |
732 | tty_vhangup_locked(tty); | 733 | tty_vhangup(tty); |
733 | tty_unlock(); | ||
734 | } | 734 | } |
735 | tty_kref_put(tty); | 735 | tty_kref_put(tty); |
736 | } else if (on_exit) { | 736 | } else if (on_exit) { |