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authorTomas Melin <tomas.melin@iki.fi>2014-09-30 10:32:08 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2014-10-30 16:57:43 -0200
commit37fa8716e2d4c4155205aa4a904835de09edbb88 (patch)
treebb1283d67250aca733e3e06ed4264554999d8d82 /drivers/media/rc
parent2279948735609d0d17d7384e776b674619f792ef (diff)
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[media] rc-main: fix lockdep splash for rc-main
lockdep reports a potential circular dependecy deadlock when registering input device. Unlock mutex rc_dev->lock prior to calling ir_raw_event_register to avoid the circular dependency since that function also calls input_register_device and rc_open. ====================================================== [ INFO: possible circular locking dependency detected ] 3.17.0-rc7+ #24 Not tainted ------------------------------------------------------- modprobe/647 is trying to acquire lock: (input_mutex){+.+.+.}, at: [<ffffffff812ed81c>] input_register_device+0x2ba/0x381 but task is already holding lock: (ir_raw_handler_lock){+.+.+.}, at: [<ffffffff813186ed>] ir_raw_event_register+0x102/0x190 which lock already depends on the new lock. [cut text] other info that might help us debug this: Chain exists of: input_mutex --> &dev->lock --> ir_raw_handler_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ir_raw_handler_lock); lock(&dev->lock); lock(ir_raw_handler_lock); lock(input_mutex); *** DEADLOCK *** 4 locks held by modprobe/647: #0: (&dev->mutex){......}, at: [<ffffffff812d19f3>] device_lock+0xf/0x11 #1: (&dev->mutex){......}, at: [<ffffffff812d19f3>] device_lock+0xf/0x11 #2: (&dev->lock){+.+.+.}, at: [<ffffffff81317fff>] rc_register_device+0x55d/0x58a #3: (ir_raw_handler_lock){+.+.+.}, at: [<ffffffff813186ed>] ir_raw_event_register+0x102/0x190 stack backtrace: CPU: 0 PID: 647 Comm: modprobe Not tainted 3.17.0-rc7+ #24 Call Trace: [<ffffffff81489d6a>] dump_stack+0x46/0x58 [<ffffffff81487699>] print_circular_bug+0x1f8/0x209 [<ffffffff81074353>] __lock_acquire+0xb54/0xeda [<ffffffff81080f17>] ? console_unlock+0x34d/0x399 [<ffffffff81074c01>] lock_acquire+0xd9/0x111 [<ffffffff812ed81c>] ? input_register_device+0x2ba/0x381 [<ffffffff8148e650>] mutex_lock_interruptible_nested+0x57/0x381 [<ffffffff812ed81c>] ? input_register_device+0x2ba/0x381 [<ffffffff81124e03>] ? kfree+0x7c/0x96 [<ffffffff812ed81c>] ? input_register_device+0x2ba/0x381 [<ffffffff81072531>] ? trace_hardirqs_on+0xd/0xf [<ffffffff812ed81c>] input_register_device+0x2ba/0x381 [<ffffffff8131a537>] ir_mce_kbd_register+0x109/0x139 [<ffffffff81318728>] ir_raw_event_register+0x13d/0x190 [<ffffffff81317e40>] rc_register_device+0x39e/0x58a [<ffffffff81072531>] ? trace_hardirqs_on+0xd/0xf [<ffffffffa00cf2e3>] nvt_probe+0x5ad/0xd52 [nuvoton_cir] [<ffffffffa00ced36>] ? nvt_resume+0x80/0x80 [nuvoton_cir] [<ffffffff81296003>] pnp_device_probe+0x8c/0xa9 [<ffffffff812d1b94>] ? driver_sysfs_add+0x6e/0x93 [<ffffffff812d203a>] driver_probe_device+0xa1/0x1e3 [<ffffffff812d217c>] ? driver_probe_device+0x1e3/0x1e3 [<ffffffff812d21ca>] __driver_attach+0x4e/0x6f [<ffffffff812d075b>] bus_for_each_dev+0x5a/0x8c [<ffffffff812d1b24>] driver_attach+0x19/0x1b [<ffffffff812d1879>] bus_add_driver+0xf1/0x1d6 [<ffffffff812d2817>] driver_register+0x87/0xbe [<ffffffffa0120000>] ? 0xffffffffa0120000 [<ffffffff81295da4>] pnp_register_driver+0x1c/0x1e [<ffffffffa0120010>] nvt_init+0x10/0x1000 [nuvoton_cir] [<ffffffff8100030e>] do_one_initcall+0xea/0x18c [<ffffffff8111497f>] ? __vunmap+0x9d/0xc7 [<ffffffff810a3ca1>] load_module+0x1c21/0x1f2c [<ffffffff810a0bce>] ? show_initstate+0x44/0x44 [<ffffffff810a404e>] SyS_init_module+0xa2/0xb1 [<ffffffff81490ed2>] system_call_fastpath+0x16/0x1b Signed-off-by: Tomas Melin <tomas.melin@iki.fi> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/media/rc')
-rw-r--r--drivers/media/rc/rc-main.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index a7991c7d010a..296de853a25d 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -1414,7 +1414,10 @@ int rc_register_device(struct rc_dev *dev)
ir_raw_init();
raw_init = true;
}
+ /* calls ir_register_device so unlock mutex here*/
+ mutex_unlock(&dev->lock);
rc = ir_raw_event_register(dev);
+ mutex_lock(&dev->lock);
if (rc < 0)
goto out_input;
}