From: Hans Verkuil <hans.verkuil@xxxxxxxxx> While working on the DMA fence API and the Request API it became clear that the core ioctl scheme was done at a too-high level. Being able to actually look at the struct passed as the ioctl argument would help a lot in decide what lock(s) to take. This patch series pushes the lock down into v4l2-ioctl.c, after video_usercopy() was called. The first patch is for the only driver that does not set unlocked_ioctl to video_ioctl2: pvrusb2. It actually does call it in its own unlocked_ioctl function. Mike, can you test this patch? I tried to test it but my pvrusb2 fails in a USB transfer (unrelated to this patch). I'll mail you separately with the details, since I've no idea what is going on. The second patch pushes the lock down. The third patch adds support for mem2mem devices by selecting the correct queue lock (capture vs output): this was never possible before. Note: in practice it appears that all m2m devices use the same lock for both capture and output queues. Perhaps this should be standardized? The final three patches require that queue->lock is always set. There are some drivers that do not set this (and Ezequiel will look at that and provide patches that will have to go in between patch 3 and 4 of this RFC series), but without that you will have performance issues with a blocking DQBUF (it will never release the core ioctl serialization lock while waiting for a new frame). I have added a test for this to v4l2-compliance. We never tested this before. Another note: the gspca vb2 conversion series I posted yesterday also remove the v4l2_disable_ioctl_locking() function, so that cleans up another little locking-related dark corner in the core. Regards, Hans Hans Verkuil (6): pvrusb2: replace pvr2_v4l2_ioctl by video_ioctl2 v4l2-core: push taking ioctl mutex down to ioctl handler. v4l2-ioctl.c: use correct vb2_queue lock for m2m devices videobuf2-core: require q->lock videobuf2: assume q->lock is always set v4l2-ioctl.c: assume queue->lock is always set .../media/common/videobuf2/videobuf2-core.c | 22 ++--- .../media/common/videobuf2/videobuf2-v4l2.c | 27 ++---- drivers/media/usb/pvrusb2/pvrusb2-v4l2.c | 83 +++++++------------ drivers/media/v4l2-core/v4l2-dev.c | 6 -- drivers/media/v4l2-core/v4l2-ioctl.c | 75 +++++++++++++++-- drivers/media/v4l2-core/v4l2-subdev.c | 17 +++- include/media/v4l2-dev.h | 9 -- include/media/v4l2-ioctl.h | 12 --- include/media/videobuf2-core.h | 2 - 9 files changed, 133 insertions(+), 120 deletions(-) -- 2.17.0
