Hello,
I'm running the Hauppauge USB-Live 2 device on an ARM OMAP3 platform.
After loading the cx231xx driver and launching v4l2grab, I immediately
get:
[ 407.087158] cx231xx #0: setPowerMode::mode = 48, No Change req.
[ 407.145477]
[ 407.147064] ======================================================
[ 407.153533] [ INFO: possible circular locking dependency detected ]
[ 407.160095] 3.2.0-00007-gb928298 #18
[ 407.163848] -------------------------------------------------------
[ 407.170410] v4l2grab/680 is trying to acquire lock:
[ 407.175537] (&mm->mmap_sem){++++++}, at: [<bf03e10c>] videobuf_qbuf+0x298/0x48c [videobuf_core]
[ 407.184783]
[ 407.184783] but task is already holding lock:
[ 407.190887] (&dev->lock#2){+.+.+.}, at: [<bf00e47c>] v4l2_ioctl+0xec/0x150 [videodev]
[ 407.199249]
[ 407.199249] which lock already depends on the new lock.
[ 407.199249]
[ 407.207824]
[ 407.207824] the existing dependency chain (in reverse order) is:
[ 407.215667]
[ 407.215667] -> #1 (&dev->lock#2){+.+.+.}:
[ 407.221435] [<c008bac8>] lock_acquire+0x98/0x100
[ 407.226928] [<c0471594>] mutex_lock_interruptible_nested+0x4c/0x37c
[ 407.234161] [<bf00e378>] v4l2_mmap+0x94/0xac [videodev]
[ 407.240295] [<c00eee5c>] mmap_region+0x2d4/0x468
[ 407.245788] [<c00ef3a0>] sys_mmap_pgoff+0x78/0xc0
[ 407.251342] [<c0013b00>] ret_fast_syscall+0x0/0x3c
[ 407.257019]
[ 407.257019] -> #0 (&mm->mmap_sem){++++++}:
[ 407.262878] [<c008b3f0>] __lock_acquire+0x1d04/0x1d94
[ 407.268829] [<c008bac8>] lock_acquire+0x98/0x100
[ 407.274291] [<c04726cc>] down_read+0x2c/0x3c
[ 407.279418] [<bf03e10c>] videobuf_qbuf+0x298/0x48c [videobuf_core]
[ 407.286529] [<bf00fbf4>] __video_do_ioctl+0x500/0x55a8 [videodev]
[ 407.293579] [<bf00f2d0>] video_usercopy+0x128/0x4d8 [videodev]
[ 407.300354] [<bf00e418>] v4l2_ioctl+0x88/0x150 [videodev]
[ 407.306671] [<c0112cd4>] do_vfs_ioctl+0x7c/0x584
[ 407.312164] [<c0113250>] sys_ioctl+0x74/0x7c
[ 407.317260] [<c0013b00>] ret_fast_syscall+0x0/0x3c
[ 407.322937]
[ 407.322937] other info that might help us debug this:
[ 407.322937]
[ 407.331329] Possible unsafe locking scenario:
[ 407.331329]
[ 407.337524] CPU0 CPU1
[ 407.342285] ---- ----
[ 407.347015] lock(&dev->lock);
[ 407.350311] lock(&mm->mmap_sem);
[ 407.356536] lock(&dev->lock);
[ 407.362457] lock(&mm->mmap_sem);
[ 407.366027]
[ 407.366027] *** DEADLOCK ***
[ 407.366027]
[ 407.372253] 1 lock held by v4l2grab/680:
[ 407.376342] #0: (&dev->lock#2){+.+.+.}, at: [<bf00e47c>] v4l2_ioctl+0xec/0x150 [videodev]
[ 407.385162]
[ 407.385162] stack backtrace:
[ 407.389739] [<c001b3b0>] (unwind_backtrace+0x0/0xf0) from [<c0087c04>] (print_circular_bug+0x1d4/0x2f0)
[ 407.399597] [<c0087c04>] (print_circular_bug+0x1d4/0x2f0) from [<c008b3f0>] (__lock_acquire+0x1d04/0x1d94)
[ 407.409729] [<c008b3f0>] (__lock_acquire+0x1d04/0x1d94) from [<c008bac8>] (lock_acquire+0x98/0x100)
[ 407.419219] [<c008bac8>] (lock_acquire+0x98/0x100) from [<c04726cc>] (down_read+0x2c/0x3c)
[ 407.427886] [<c04726cc>] (down_read+0x2c/0x3c) from [<bf03e10c>] (videobuf_qbuf+0x298/0x48c [videobuf_core])
[ 407.438201] [<bf03e10c>] (videobuf_qbuf+0x298/0x48c [videobuf_core]) from [<bf00fbf4>] (__video_do_ioctl+0x500/0x55a8 [videodev])
[ 407.450469] [<bf00fbf4>] (__video_do_ioctl+0x500/0x55a8 [videodev]) from [<bf00f2d0>] (video_usercopy+0x128/0x4d8 [videodev])
[ 407.462341] [<bf00f2d0>] (video_usercopy+0x128/0x4d8 [videodev]) from [<bf00e418>] (v4l2_ioctl+0x88/0x150 [videodev])
[ 407.473480] [<bf00e418>] (v4l2_ioctl+0x88/0x150 [videodev]) from [<c0112cd4>] (do_vfs_ioctl+0x7c/0x584)
[ 407.483337] [<c0112cd4>] (do_vfs_ioctl+0x7c/0x584) from [<c0113250>] (sys_ioctl+0x74/0x7c)
[ 407.492004] [<c0113250>] (sys_ioctl+0x74/0x7c) from [<c0013b00>] (ret_fast_syscall+0x0/0x3c)
[ 407.500915] cx231xx #0: cx231xx_stop_stream():: ep_mask = 8
Best regards,
Thomas Petazzoni
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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