Commits
Max Filippov committed efefbcc5002
xtensa: ISS: fix timer_lock usage in rs_open
This fixes the following lockdep splat:
[ 66.460000] =================================
[ 66.460000] [ INFO: inconsistent lock state ]
[ 66.460000] 3.9.0-rc5-00161-ga48dd49 #4 Not tainted
[ 66.460000] ---------------------------------
[ 66.460000] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
[ 66.460000] swapper/1 [HC0[0]:SC1[1]:HE1:SE0] takes:
[ 66.460000] (timer_lock){+.?...}, at: [<d0006cde>] rs_poll+0x12/0xdc
[ 66.460000] {SOFTIRQ-ON-W} state was registered at:
[ 66.460000] [<d00421f0>] lock_acquire+0xec/0x13c
[ 66.460000] [<d01ea036>] _raw_spin_lock+0x3a/0x84
[ 66.460000] [<d0006c8c>] rs_open+0x18/0x58
[ 66.460000] [<d0139ea2>] tty_open+0x262/0x3cc
[ 66.460000] [<d00942e0>] chrdev_open+0x8c/0xe0
[ 66.460000] [<d00907b2>] do_dentry_open$isra$16+0x10e/0x190
[ 66.460000] [<d0091141>] finish_open+0x39/0x48
[ 66.460000] [<d009a0b4>] do_last$isra$34+0x6c4/0x824
[ 66.460000] [<d009a27a>] path_openat+0x66/0x310
[ 66.460000] [<d009a53a>] do_filp_open+0x16/0x44
[ 66.460000] [<d0091445>] do_sys_open+0xd5/0x13c
[ 66.460000] [<d00914be>] sys_open+0x12/0x18
[ 66.460000] [<d0413ffc>] kernel_init_freeable+0xe4/0x12c
[ 66.460000] [<d01e2a9c>] kernel_init+0xc/0x9c
[ 66.460000] [<d00044fc>] ret_from_kernel_thread+0x8/0xc
[ 66.460000] irq event stamp: 132542
[ 66.460000] hardirqs last enabled at (132542): [<d01ea2ec>] _raw_spin_unlock_irq+0x30/0x44
[ 66.460000] hardirqs last disabled at (132541): [<d01ea11e>] _raw_spin_lock_irq+0xe/0x8c
[ 66.460000] softirqs last enabled at (132234): [<d0017d32>] __do_softirq+0x216/0x2a4
[ 66.460000] softirqs last disabled at (132539): [<d0018024>] irq_exit+0x38/0x40
[ 66.460000]
[ 66.460000] other info that might help us debug this:
[ 66.460000] Possible unsafe locking scenario:
[ 66.460000]
[ 66.460000] CPU0
[ 66.460000] ----
[ 66.460000] lock(timer_lock);
[ 66.460000] <Interrupt>
[ 66.460000] lock(timer_lock);
[ 66.460000]
[ 66.460000] *** DEADLOCK ***
[ 66.460000]
[ 66.460000] 1 lock held by swapper/1:
[ 66.460000] #0: (((&serial_timer))){+.-...}, at: [<d001c65c>] call_timer_fn+0x0/0x1f0
[ 66.460000]
Stack: d7c2fac0 00000018 00000004 00000001 d7c2faa0 00000004 00000006 d7c2fa90
9003e87c d7c2fae0 d7c30000 d025a87c 00000001 0000000f 00000000 d7c2fac0
9004005d d7c2fb10 d7c30000 d7c30338 00000001 00000001 00000000 d7c30338
[ 66.460000] Call Trace:
[ 66.460000] [<d01e4f93>] print_usage_bug$part$26+0x1c3/0x1c8
[ 66.460000] [<d003e87c>] mark_lock+0x2b4/0x440
[ 66.460000] [<d004005d>] __lock_acquire+0x54d/0x16c4
[ 66.460000] [<d00421f0>] lock_acquire+0xec/0x13c
[ 66.460000] [<d01ea036>] _raw_spin_lock+0x3a/0x84
[ 66.460000] [<d0006cde>] rs_poll+0x12/0xdc
[ 66.460000] [<d001c71a>] call_timer_fn+0xbe/0x1f0
[ 66.460000] [<d001cd90>] run_timer_softirq+0x198/0x1f4
[ 66.460000] [<d0017c30>] __do_softirq+0x114/0x2a4
[ 66.460000] [<d0018024>] irq_exit+0x38/0x40
[ 66.460000] [<d00046c0>] do_IRQ+0x44/0x48
[ 66.460000] [<d0005c58>] do_interrupt+0x4c/0x54
[ 66.460000] [<d0003c80>] common_exception_return+0x0/0x5c
[ 66.460000] [<d006682c>] free_pcppages_bulk+0x254/0x308
[ 66.460000]
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>