Commit c38077d39c7e ("[media] media-device: get rid of the spinlock")
introduced a deadlock in the MEDIA_IOC_ENUM_LINKS ioctl handler.
Revert the broken commit as well as another that has been merged on top, and
let's implement a proper fix instead of half-baked hacks this time.
[ 2760.127749] INFO: task media-ctl:954 blocked for more than 120 seconds.
[ 2760.131867] Not tainted 4.5.0+ #357
[ 2760.134622] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2760.139310] media-ctl D ffffffc000086bcc 0 954 671 0x00000001
[ 2760.143618] Call trace:
[ 2760.145601] [<ffffffc000086bcc>] __switch_to+0x90/0xa4
[ 2760.148941] [<ffffffc0004e6ef0>] __schedule+0x188/0x5b0
[ 2760.152309] [<ffffffc0004e7354>] schedule+0x3c/0xa0
[ 2760.155495] [<ffffffc0004e7768>] schedule_preempt_disabled+0x20/0x38
[ 2760.159423] [<ffffffc0004e8d28>] __mutex_lock_slowpath+0xc4/0x148
[ 2760.163217] [<ffffffc0004e8df0>] mutex_lock+0x44/0x5c
[ 2760.166483] [<ffffffc0003e87d4>] find_entity+0x2c/0xac
[ 2760.169773] [<ffffffc0003e8d34>] __media_device_enum_links+0x20/0x1dc
[ 2760.173711] [<ffffffc0003e9718>] media_device_ioctl+0x214/0x33c
[ 2760.177384] [<ffffffc0003e9eec>] media_ioctl+0x24/0x3c
[ 2760.180671] [<ffffffc0001bee64>] do_vfs_ioctl+0xac/0x758
[ 2760.184026] [<ffffffc0001bf594>] SyS_ioctl+0x84/0x98
[ 2760.187196] [<ffffffc000085d30>] el0_svc_naked+0x24/0x28
Laurent Pinchart (2):
Revert "[media] media-device: use kref for media_device instance"
Revert "[media] media-device: get rid of the spinlock"
drivers/media/media-device.c | 143 ++++++++++-----------------------
drivers/media/media-entity.c | 16 ++--
drivers/media/usb/au0828/au0828-core.c | 3 +-
include/media/media-device.h | 34 ++------
sound/usb/media.c | 3 +-
5 files changed, 61 insertions(+), 138 deletions(-)
--
Regards,
Laurent Pinchart
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