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authorAndrew Morton <akpm@linux-foundation.org>2008-05-14 16:05:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-14 19:11:15 -0700
commit9ffee4cbc51907755809d98613d9e7133612803a (patch)
treef282b916b8ff63d9e70d0f7f134baf1b81e94301
parente7e72bf641b1fc7b9df6f40bd2c36dfccd8d647c (diff)
downloadlinux-stericsson-9ffee4cbc51907755809d98613d9e7133612803a.tar.gz
tty_check_change(): avoid taking tasklist_lock while holding tty->ctrl_lock
May 11 09:42:27 [kernel] [ 1104.496819] rarian-sk-get-c[5630]: segfault at 0 ip 7f478556caf0 sp 7fff8e3fe338 error 4 in libc-2.6.1.so[7f47854f9000+136000] May 11 10:59:48 [kernel] [ 2494.165792] May 11 10:59:48 [kernel] [ 2494.165794] ======================================================= May 11 10:59:48 [kernel] [ 2494.165801] [ INFO: possible circular locking dependency detected ] May 11 10:59:48 [kernel] [ 2494.165805] 2.6.26-rc1-00007-g91b3a7a #217 May 11 10:59:48 [kernel] [ 2494.165807] ------------------------------------------------------- May 11 10:59:48 [kernel] [ 2494.165809] less/7053 is trying to acquire lock: May 11 10:59:48 [kernel] [ 2494.165812] (tasklist_lock){..??}, at: [<ffffffff80232e95>] is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.165821] May 11 10:59:48 [kernel] [ 2494.165822] but task is already holding lock: May 11 10:59:48 [kernel] [ 2494.165824] (&tty->ctrl_lock){....}, at: [<ffffffff803d5f31>] tty_check_change+0x61/0x110 May 11 10:59:48 [kernel] [ 2494.165831] May 11 10:59:48 [kernel] [ 2494.165832] which lock already depends on the new lock. May 11 10:59:48 [kernel] [ 2494.165833] May 11 10:59:48 [kernel] [ 2494.165835] May 11 10:59:48 [kernel] [ 2494.165836] the existing dependency chain (in reverse order) is: May 11 10:59:48 [kernel] [ 2494.165838] May 11 10:59:48 [kernel] [ 2494.165839] -> #2 (&tty->ctrl_lock){....}: May 11 10:59:48 [kernel] [ 2494.165843] [<ffffffff80253796>] __lock_acquire+0xf86/0x1080 May 11 10:59:48 [kernel] [ 2494.165851] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.165858] [<ffffffff804deee0>] _spin_lock_irqsave+0x40/0x60 May 11 10:59:48 [kernel] [ 2494.165866] [<ffffffff803d31b5>] __proc_set_tty+0x35/0xe0 May 11 10:59:48 [kernel] [ 2494.165873] [<ffffffff803d76d4>] tty_ioctl+0xbf4/0xfe0 May 11 10:59:48 [kernel] [ 2494.165880] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.165888] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.165895] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.165902] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.165910] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.165924] May 11 10:59:48 [kernel] [ 2494.165925] -> #1 (&sighand->siglock){++..}: May 11 10:59:48 [kernel] [ 2494.165929] [<ffffffff80253796>] __lock_acquire+0xf86/0x1080 May 11 10:59:48 [kernel] [ 2494.165936] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.165943] [<ffffffff804dec1f>] _spin_lock+0x2f/0x40 May 11 10:59:48 [kernel] [ 2494.165951] [<ffffffff8022d5a3>] copy_process+0x973/0x1210 May 11 10:59:48 [kernel] [ 2494.165959] [<ffffffff8022df12>] do_fork+0x82/0x2f0 May 11 10:59:48 [kernel] [ 2494.165967] [<ffffffff8020bfe1>] kernel_thread+0x81/0xde May 11 10:59:48 [kernel] [ 2494.165974] [<ffffffff8020c048>] child_rip+0xa/0x12 May 11 10:59:48 [kernel] [ 2494.165981] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.166038] May 11 10:59:48 [kernel] [ 2494.166039] -> #0 (tasklist_lock){..??}: May 11 10:59:48 [kernel] [ 2494.166043] [<ffffffff802535ab>] __lock_acquire+0xd9b/0x1080 May 11 10:59:48 [kernel] [ 2494.166050] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.166057] [<ffffffff804dede2>] _read_lock+0x32/0x50 May 11 10:59:48 [kernel] [ 2494.166063] [<ffffffff80232e95>] is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.166071] [<ffffffff803d5f80>] tty_check_change+0xb0/0x110 May 11 10:59:48 [kernel] [ 2494.166078] [<ffffffff803dac5f>] set_termios+0x1f/0x4c0 May 11 10:59:48 [kernel] [ 2494.166085] [<ffffffff803db379>] tty_mode_ioctl+0x279/0x3e0 May 11 10:59:48 [kernel] [ 2494.166092] [<ffffffff803db51d>] n_tty_ioctl+0x3d/0x260 May 11 10:59:48 [kernel] [ 2494.166100] [<ffffffff803d6c34>] tty_ioctl+0x154/0xfe0 May 11 10:59:48 [kernel] [ 2494.166107] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.166114] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.166121] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.166128] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.166135] [<ffffffffffffffff>] 0xffffffffffffffff May 11 10:59:48 [kernel] [ 2494.166142] May 11 10:59:48 [kernel] [ 2494.166143] other info that might help us debug this: May 11 10:59:48 [kernel] [ 2494.166144] May 11 10:59:48 [kernel] [ 2494.166146] 1 lock held by less/7053: May 11 10:59:48 [kernel] [ 2494.166148] #0: (&tty->ctrl_lock){....}, at: [<ffffffff803d5f31>] tty_check_change+0x61/0x110 May 11 10:59:48 [kernel] [ 2494.166155] May 11 10:59:48 [kernel] [ 2494.166156] stack backtrace: May 11 10:59:48 [kernel] [ 2494.166159] Pid: 7053, comm: less Not tainted 2.6.26-rc1-00007-g91b3a7a #217 May 11 10:59:48 [kernel] [ 2494.166161] May 11 10:59:48 [kernel] [ 2494.166162] Call Trace: May 11 10:59:48 [kernel] [ 2494.166168] [<ffffffff80251223>] print_circular_bug_tail+0x83/0x90 May 11 10:59:48 [kernel] [ 2494.166172] [<ffffffff80250889>] ? print_circular_bug_entry+0x49/0x60 May 11 10:59:48 [kernel] [ 2494.166178] [<ffffffff802535ab>] __lock_acquire+0xd9b/0x1080 May 11 10:59:48 [kernel] [ 2494.166184] [<ffffffff80232e95>] ? is_current_pgrp_orphaned+0x15/0x50 May 11 10:59:48 [kernel] [ 2494.166189] [<ffffffff80253922>] lock_acquire+0x92/0xc0 May 11 10:59:48 [kernel] [ 2494.166206] [<ffffffff803d5f80>] tty_check_change+0xb0/0x110 May 11 10:59:48 [kernel] [ 2494.166211] [<ffffffff803dac5f>] set_termios+0x1f/0x4c0 May 11 10:59:48 [kernel] [ 2494.166216] [<ffffffff803d3423>] ? tty_ldisc_try+0x23/0x60 May 11 10:59:48 [kernel] [ 2494.166220] [<ffffffff803d3444>] ? tty_ldisc_try+0x44/0x60 May 11 10:59:48 [kernel] [ 2494.166224] [<ffffffff804df2c5>] ? _spin_unlock_irqrestore+0x65/0x80 May 11 10:59:48 [kernel] [ 2494.166230] [<ffffffff803db379>] tty_mode_ioctl+0x279/0x3e0 May 11 10:59:48 [kernel] [ 2494.166234] [<ffffffff803d3444>] ? tty_ldisc_try+0x44/0x60 May 11 10:59:48 [kernel] [ 2494.166239] [<ffffffff803db51d>] n_tty_ioctl+0x3d/0x260 May 11 10:59:48 [kernel] [ 2494.166244] [<ffffffff803d6c34>] tty_ioctl+0x154/0xfe0 May 11 10:59:48 [kernel] [ 2494.166249] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166256] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166263] [<ffffffff80252baa>] ? __lock_acquire+0x39a/0x1080 May 11 10:59:48 [kernel] [ 2494.166269] [<ffffffff802a05e1>] vfs_ioctl+0x31/0x90 May 11 10:59:48 [kernel] [ 2494.166274] [<ffffffff802a06b3>] do_vfs_ioctl+0x73/0x2d0 May 11 10:59:48 [kernel] [ 2494.166280] [<ffffffff802a095a>] sys_ioctl+0x4a/0x80 May 11 10:59:48 [kernel] [ 2494.166286] [<ffffffff8020b5ab>] system_call_after_swapgs+0x7b/0x80 May 11 10:59:48 [kernel] [ 2494.166292] Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Reported-by: Marcin Slusarz <marcin.slusarz@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/char/tty_io.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 49c1a2267a55..e94bee032314 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1215,10 +1215,11 @@ int tty_check_change(struct tty_struct *tty)
if (!tty->pgrp) {
printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
- goto out;
+ goto out_unlock;
}
if (task_pgrp(current) == tty->pgrp)
- goto out;
+ goto out_unlock;
+ spin_unlock_irqrestore(&tty->ctrl_lock, flags);
if (is_ignored(SIGTTOU))
goto out;
if (is_current_pgrp_orphaned()) {
@@ -1229,6 +1230,8 @@ int tty_check_change(struct tty_struct *tty)
set_thread_flag(TIF_SIGPENDING);
ret = -ERESTARTSYS;
out:
+ return ret;
+out_unlock:
spin_unlock_irqrestore(&tty->ctrl_lock, flags);
return ret;
}