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authorShaohua Li <shaohua.li@intel.com>2012-02-06 08:57:29 +0100
committerJens Axboe <axboe@kernel.dk>2012-02-06 08:57:29 +0100
commit9fa73472ddbcd3da87d35a7f4566eaaf345f798e (patch)
tree6564619c63104411c1370249029f2389510790c6 /block/blk-ioc.c
parent05c30b9551f1904d9950ad0d28e65fc4ff3c8a8e (diff)
downloadlinux-linaro-stable-9fa73472ddbcd3da87d35a7f4566eaaf345f798e.tar.gz
block: fix ioc locking warning
Meelis reported a warning: WARNING: at kernel/timer.c:1122 run_timer_softirq+0x199/0x1ec() Hardware name: 939Dual-SATA2 timer: cfq_idle_slice_timer+0x0/0xaa preempt leak: 00000102 -> 00000103 Modules linked in: sr_mod cdrom videodev media drm_kms_helper ohci_hcd ehci_hcd v4l2_compat_ioctl32 usbcore i2c_ali15x3 snd_seq drm snd_timer snd_seq Pid: 0, comm: swapper Not tainted 3.3.0-rc2-00110-gd125666 #176 Call Trace: <IRQ> [<ffffffff81022aaa>] warn_slowpath_common+0x7e/0x96 [<ffffffff8114c485>] ? cfq_slice_expired+0x1d/0x1d [<ffffffff81022b56>] warn_slowpath_fmt+0x41/0x43 [<ffffffff8114c526>] ? cfq_idle_slice_timer+0xa1/0xaa [<ffffffff8114c485>] ? cfq_slice_expired+0x1d/0x1d [<ffffffff8102c124>] run_timer_softirq+0x199/0x1ec [<ffffffff81047a53>] ? timekeeping_get_ns+0x12/0x31 [<ffffffff810145fd>] ? apic_write+0x11/0x13 [<ffffffff81027475>] __do_softirq+0x74/0xfa [<ffffffff812f337a>] call_softirq+0x1a/0x30 [<ffffffff81002ff9>] do_softirq+0x31/0x68 [<ffffffff810276cf>] irq_exit+0x3d/0xa3 [<ffffffff81014aca>] smp_apic_timer_interrupt+0x6b/0x77 [<ffffffff812f2de9>] apic_timer_interrupt+0x69/0x70 <EOI> [<ffffffff81040136>] ? sched_clock_cpu+0x73/0x7d [<ffffffff81040136>] ? sched_clock_cpu+0x73/0x7d [<ffffffff8100801f>] ? default_idle+0x1e/0x32 [<ffffffff81008019>] ? default_idle+0x18/0x32 [<ffffffff810008b1>] cpu_idle+0x87/0xd1 [<ffffffff812de861>] rest_init+0x85/0x89 [<ffffffff81659a4d>] start_kernel+0x2eb/0x2f8 [<ffffffff8165926e>] x86_64_start_reservations+0x7e/0x82 [<ffffffff81659362>] x86_64_start_kernel+0xf0/0xf7 this_q == locked_q is possible. There are two problems here: 1. In UP case, there is preemption counter issue as spin_trylock always successes. 2. In SMP case, the loop breaks too earlier. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reported-by: Meelis Roos <mroos@linux.ee> Reported-by: Knut Petersen <Knut_Petersen@t-online.de> Tested-by: Knut Petersen <Knut_Petersen@t-online.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-ioc.c')
-rw-r--r--block/blk-ioc.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 27a06e00eaec..7490b6da2453 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -204,7 +204,9 @@ void put_io_context(struct io_context *ioc, struct request_queue *locked_q)
spin_unlock(last_q->queue_lock);
last_q = NULL;
- if (!spin_trylock(this_q->queue_lock))
+ /* spin_trylock() always successes in UP case */
+ if (this_q != locked_q &&
+ !spin_trylock(this_q->queue_lock))
break;
last_q = this_q;
continue;