The lockdep hunter mentions a non consistent usage of spin_lock and
spin_lock_irqsafe in the composite_disconnect and usb_function_activate
function:

[   15.700897] =================================
[   15.705255] [ INFO: inconsistent lock state ]
[   15.709617] 3.5.0-rc5+ #413 Not tainted
[   15.713453] ---------------------------------
[   15.717812] inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
[   15.723822] uvc-gadget/116 [HC1[1]:SC0[0]:HE0:SE1] takes:
[   15.729222]  (&(&cdev->lock)->rlock){?.+...}, at: [<7f0049e8>] composite_disconnect+0x2c/0x74 [g_webcam]
[   15.738797] {HARDIRQ-ON-W} state was registered at:
[   15.743677]   [<8006de3c>] mark_lock+0x148/0x688
[   15.748325]   [<8006ecb0>] __lock_acquire+0x934/0x1b74
[   15.753481]   [<8007047c>] lock_acquire+0x98/0x138
[   15.758288]   [<804c776c>] _raw_spin_lock+0x4c/0x84
[   15.763188]   [<7f006ae4>] usb_function_activate+0x28/0x94 [g_webcam]
[   15.769652]   [<7f00820c>] usb_ep_autoconfig_reset+0x78/0x98 [g_webcam]
[   15.776287]   [<7f0082a4>] uvc_v4l2_open+0x78/0x94 [g_webcam]
[   15.782054]   [<80366a38>] v4l2_open+0x104/0x130
[   15.786697]   [<800efd30>] chrdev_open+0xa0/0x170
[   15.791423]   [<800e9718>] do_dentry_open.isra.13+0x1e8/0x264
[   15.797186]   [<800ea5d4>] nameidata_to_filp+0x58/0x94
[   15.802340]   [<800fa29c>] do_last.isra.31+0x2a0/0x808
[   15.807497]   [<800faa40>] path_openat+0xc8/0x3e8
[   15.812216]   [<800fae90>] do_filp_open+0x3c/0x90
[   15.816936]   [<800ea6fc>] do_sys_open+0xec/0x184
[   15.821655]   [<800ea7c4>] sys_open+0x30/0x34
[   15.826027]   [<8000e5c0>] ret_fast_syscall+0x0/0x48
[   15.831015] irq event stamp: 6048
[   15.834330] hardirqs last  enabled at (6047): [<804c81b8>] _raw_spin_unlock_irqrestore+0x40/0x54
[   15.843132] hardirqs last disabled at (6048): [<8000e174>] __irq_svc+0x34/0x60
[   15.850370] softirqs last  enabled at (5940): [<80028380>] __do_softirq+0x188/0x270
[   15.858043] softirqs last disabled at (5935): [<80028944>] irq_exit+0xa0/0xa8
[   15.865195]
[   15.865195] other info that might help us debug this:
[   15.871724]  Possible unsafe locking scenario:
[   15.871724]
[   15.877645]        CPU0
[   15.880091]        ----
[   15.882537]   lock(&(&cdev->lock)->rlock);
[   15.886659]   <Interrupt>
[   15.889278]     lock(&(&cdev->lock)->rlock);
[   15.893573]
[   15.893573]  *** DEADLOCK ***
[   15.893573]
[   15.899496] no locks held by uvc-gadget/116.
[   15.903765]
[   15.903765] stack backtrace:
[   15.908125] Backtrace:
[   15.910604] [<80012038>] (dump_backtrace+0x0/0x114) from [<804bf8a4>] (dump_stack+0x20/0x24)
[   15.919043]  r6:dfb8e6f0 r5:dfb8e400 r4:809717ec r3:60000193
[   15.924766] [<804bf884>] (dump_stack+0x0/0x24) from [<804c0c0c>] (print_usage_bug+0x258/0x2c0)
[   15.933388] [<804c09b4>] (print_usage_bug+0x0/0x2c0) from [<8006e240>] (mark_lock+0x54c/0x688)
[   15.942006] [<8006dcf4>] (mark_lock+0x0/0x688) from [<8006edb8>] (__lock_acquire+0xa3c/0x1b74)
[   15.950625] [<8006e37c>] (__lock_acquire+0x0/0x1b74) from [<8007047c>] (lock_acquire+0x98/0x138)
[   15.959418] [<800703e4>] (lock_acquire+0x0/0x138) from [<804c78fc>] (_raw_spin_lock_irqsave+0x58/0x94)
[   15.968736] [<804c78a4>] (_raw_spin_lock_irqsave+0x0/0x94) from [<7f0049e8>] (composite_disconnect+0x2c/0x74 [g_webcam])
[   15.979605]  r7:00000012 r6:df82b0c4 r5:ded755bc r4:ded75580
[   15.985331] [<7f0049bc>] (composite_disconnect+0x0/0x74 [g_webcam]) from [<8033c170>] (_gadget_stop_activity+0xc4/0x120)
[   15.996200]  r6:df82b0c4 r5:df82b0c8 r4:df82b0d0 r3:7f0049bc
[   16.001919] [<8033c0ac>] (_gadget_stop_activity+0x0/0x120) from [<8033e390>] (udc_irq+0x724/0xcb8)
[   16.010877]  r6:df82b010 r5:00000000 r4:df82b010 r3:00000000
[   16.016595] [<8033dc6c>] (udc_irq+0x0/0xcb8) from [<8033baec>] (ci_irq+0x64/0xdc)
[   16.024086] [<8033ba88>] (ci_irq+0x0/0xdc) from [<80086538>] (handle_irq_event_percpu+0x74/0x298)
[   16.032958]  r5:807fd414 r4:df38fdc0
[   16.036566] [<800864c4>] (handle_irq_event_percpu+0x0/0x298) from [<800867a8>] (handle_irq_event+0x4c/0x6c)
[   16.046315] [<8008675c>] (handle_irq_event+0x0/0x6c) from [<80089318>] (handle_level_irq+0xbc/0x11c)
[   16.055447]  r6:def04000 r5:807fd414 r4:807fd3c0 r3:00020000
[   16.061166] [<8008925c>] (handle_level_irq+0x0/0x11c) from [<80085cc8>] (generic_handle_irq+0x38/0x4c)
[   16.070472]  r5:807f7f64 r4:8081e9f8
[   16.074082] [<80085c90>] (generic_handle_irq+0x0/0x4c) from [<8000ef98>] (handle_IRQ+0x5c/0xbc)
[   16.082788] [<8000ef3c>] (handle_IRQ+0x0/0xbc) from [<800085cc>] (tzic_handle_irq+0x6c/0x9c)
[   16.091225]  r8:00000000 r7:def059b0 r6:00000001 r5:00000000 r4:00000000
r3:00000012
[   16.099141] [<80008560>] (tzic_handle_irq+0x0/0x9c) from [<8000e184>] (__irq_svc+0x44/0x60)
[   16.107494] Exception stack(0xdef059b0 to 0xdef059f8)
[   16.112550] 59a0:                                     00000001 00000001 00000000 dfb8e400
[   16.120732] 59c0: 40000013 81a2e500 00000000 81a2e500 00000000 00000000 80862418 def05a0c
[   16.128912] 59e0: def059c8 def059f8 80070e24 804c81bc 20000013 ffffffff
[   16.135542] [<804c8178>] (_raw_spin_unlock_irqrestore+0x0/0x54) from [<8003d0ec>] (__queue_work+0x108/0x470)
[   16.145369]  r5:dfb1a30c r4:81b93c00
[   16.148978] [<8003cfe4>] (__queue_work+0x0/0x470) from [<8003d4e0>] (queue_work_on+0x4c/0x54)
[   16.157511] [<8003d494>] (queue_work_on+0x0/0x54) from [<8003d544>] (queue_work+0x30/0x34)
[   16.165774]  r6:df2e6900 r5:80e0c2f8 r4:dfb1a2c8 r3:def04000
[   16.171495] [<8003d514>] (queue_work+0x0/0x34) from [<80493284>] (rpc_make_runnable+0x9c/0xac)
[   16.180113] [<804931e8>] (rpc_make_runnable+0x0/0xac) from [<80493c88>] (rpc_execute+0x40/0xa8)
[   16.188811]  r5:def05ad4 r4:dfb1a2c8
[   16.192426] [<80493c48>] (rpc_execute+0x0/0xa8) from [<8048c734>] (rpc_run_task+0xa8/0xb4)
[   16.200690]  r8:00000001 r7:df74f520 r6:ded75700 r5:def05ad4 r4:dfb1a2c8
r3:00000002
[   16.208618] [<8048c68c>] (rpc_run_task+0x0/0xb4) from [<801f1608>] (nfs_initiate_read+0xb4/0xd4)
[   16.217403]  r5:df3e86c0 r4:00000000
[   16.221015] [<801f1554>] (nfs_initiate_read+0x0/0xd4) from [<801f1c64>] (nfs_generic_pg_readpages+0x9c/0x114)
[   16.230937] [<801f1bc8>] (nfs_generic_pg_readpages+0x0/0x114) from [<801f0744>] (__nfs_pageio_add_request+0xe8/0x214)
[   16.241545]  r8:000bf000 r7:00000000 r6:00000000 r5:deef4640 r4:def05c1c
r3:801f1bc8
[   16.249463] [<801f065c>] (__nfs_pageio_add_request+0x0/0x214) from [<801f0e3c>] (nfs_pageio_add_request+0x28/0x54)
[   16.259818] [<801f0e14>] (nfs_pageio_add_request+0x0/0x54) from [<801f1394>] (readpage_async_filler+0x114/0x170)
[   16.269992]  r5:def05c58 r4:80fd7300
[   16.273607] [<801f1280>] (readpage_async_filler+0x0/0x170) from [<800bb418>] (read_cache_pages+0xa0/0x108)
[   16.283259]  r8:00200200 r7:00100100 r6:df74f654 r5:def05cd0 r4:80fd7300
[   16.290034] [<800bb378>] (read_cache_pages+0x0/0x108) from [<801f218c>] (nfs_readpages+0xc4/0x168)
[   16.298999] [<801f20c8>] (nfs_readpages+0x0/0x168) from [<800bb1d0>] (__do_page_cache_readahead+0x254/0x354)
[   16.308833] [<800baf7c>] (__do_page_cache_readahead+0x0/0x354) from [<800bb5d0>] (ra_submit+0x38/0x40)
[   16.318145] [<800bb598>] (ra_submit+0x0/0x40) from [<800bb6b0>] (ondemand_readahead+0xd8/0x3b0)
[   16.326851] [<800bb5d8>] (ondemand_readahead+0x0/0x3b0) from [<800bba20>] (page_cache_async_readahead+0x98/0xa8)
[   16.337043] [<800bb988>] (page_cache_async_readahead+0x0/0xa8) from [<800b2118>] (generic_file_aio_read+0x5b4/0x7c4)
[   16.347565]  r6:00000000 r5:df74f654 r4:80fd70a0
[   16.352231] [<800b1b64>] (generic_file_aio_read+0x0/0x7c4) from [<801e82c0>] (nfs_file_read+0x7c/0xcc)
[   16.361544] [<801e8244>] (nfs_file_read+0x0/0xcc) from [<800eab80>] (do_sync_read+0xb4/0xf4)
[   16.369981]  r9:00000000 r8:def05f70 r7:00000000 r6:00000000 r5:dec34900
r4:fffffdee
[   16.377896] [<800eaacc>] (do_sync_read+0x0/0xf4) from [<800eb548>] (vfs_read+0xb4/0x144)
[   16.385987]  r8:00000000 r7:def05f70 r6:76a95008 r5:003e3dd6 r4:dec34900
[   16.392761] [<800eb494>] (vfs_read+0x0/0x144) from [<800eb624>] (sys_read+0x4c/0x78)
[   16.400504]  r8:00000000 r7:00000003 r6:003e3dd6 r5:76a95008 r4:dec34900
[   16.407279] [<800eb5d8>] (sys_read+0x0/0x78) from [<8000e5c0>] (ret_fast_syscall+0x0/0x48)
[   16.415543]  r9:def04000 r8:8000e864 r6:000086b4 r5:00000000 r4:00000000
[   20.872729]  gadget: high-speed config #1: Video
[   20.877368]  gadget: uvc_function_set_alt(0, 0)
[   20.881908]  gadget: uvc_function_set_alt(1, 0)
[   20.891464]  gadget: uvc_function_set_alt(1, 0)
Signed-off-by: NMichael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: NFelipe Balbi <balbi@ti.com>