usb: gadget: uvc: allow for application to cleanly shutdown

usb: gadget: uvc: allow for application to cleanly shutdown

Several types of kernel panics can occur due to timing during the uvc
gadget removal. This appears to be a problem with gadget resources being
managed by both the client application's v4l2 open/close and the UDC
gadget bind/unbind. Since the concept of USB_GADGET_DELAYED_STATUS
doesn't exist for unbind, add a wait to allow for the application to
close out.

Some examples of the panics that can occur are:

<1>[ 1147.652313] Unable to handle kernel NULL pointer dereference at
virtual address 0000000000000028
<4>[ 1147.652510] Call trace:
<4>[ 1147.652514]  usb_gadget_disconnect+0x74/0x1f0
<4>[ 1147.652516]  usb_gadget_deactivate+0x38/0x168
<4>[ 1147.652520]  usb_function_deactivate+0x54/0x90
<4>[ 1147.652524]  uvc_function_disconnect+0x14/0x38
<4>[ 1147.652527]  uvc_v4l2_release+0x34/0xa0
<4>[ 1147.652537]  __fput+0xdc/0x2c0
<4>[ 1147.652540]  ____fput+0x10/0x1c
<4>[ 1147.652545]  task_work_run+0xe4/0x12c
<4>[ 1147.652549]  do_notify_resume+0x108/0x168

<1>[  282.950561][ T1472] Unable to handle kernel NULL pointer
dereference at virtual address 00000000000005b8
<6>[  282.953111][ T1472] Call trace:
<6>[  282.953121][ T1472]  usb_function_deactivate+0x54/0xd4
<6>[  282.953134][ T1472]  uvc_v4l2_release+0xac/0x1e4
<6>[  282.953145][ T1472]  v4l2_release+0x134/0x1f0
<6>[  282.953167][ T1472]  __fput+0xf4/0x428
<6>[  282.953178][ T1472]  ____fput+0x14/0x24
<6>[  282.953193][ T1472]  task_work_run+0xac/0x130

<3>[  213.410077][   T29] configfs-gadget gadget: uvc: Failed to queue
request (-108).
<1>[  213.410116][   T29] Unable to handle kernel NULL pointer
dereference at virtual address 0000000000000003
<6>[  213.413460][   T29] Call trace:
<6>[  213.413474][   T29]  uvcg_video_pump+0x1f0/0x384
<6>[  213.413489][   T29]  process_one_work+0x2a4/0x544
<6>[  213.413502][   T29]  worker_thread+0x350/0x784
<6>[  213.413515][   T29]  kthread+0x2ac/0x320
<6>[  213.413528][   T29]  ret_from_fork+0x10/0x30

Signed-off-by: Dan Vacura <w36195@motorola.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220503201039.71720-1-w36195@motorola.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>