Make sure that all the async work is finished when we stop the status urb.
To: Yunke Cao yunkec@chromium.org To: Sergey Senozhatsky senozhatsky@chromium.org To: Max Staudt mstaudt@google.com To: Laurent Pinchart laurent.pinchart@ideasonboard.com To: Mauro Carvalho Chehab mchehab@kernel.org Cc: linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Ricardo Ribalda ribalda@chromium.org
--- Changes in v2: - Add a patch for not kalloc dev->status - Redo the logic mechanism, so it also works with suspend (Thanks Yunke!) - Link to v1: https://lore.kernel.org/r/20221212-uvc-race-v1-0-c52e1783c31d@chromium.org
--- Ricardo Ribalda (2): media: uvcvideo: Fix race condition with usb_kill_urb media: uvcvideo: Do not alloc dev->status
drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ drivers/media/usb/uvc/uvc_status.c | 15 +++++++-------- drivers/media/usb/uvc/uvcvideo.h | 3 ++- 3 files changed, 12 insertions(+), 9 deletions(-) --- base-commit: 0ec5a38bf8499f403f81cb81a0e3a60887d1993c change-id: 20221212-uvc-race-09276ea68bf8
Best regards,
usb_kill_urb warranties that all the handlers are finished when it returns, but does not protect against threads that might be handling asynchronously the urb.
For UVC, the function uvc_ctrl_status_event_async() takes care of control changes asynchronously.
If the code is executed in the following order:
CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_ctrl_status_event_work() uvc_status_start() -> FAIL
Then uvc_status_start will keep failing and this error will be shown:
<4>[ 5.540139] URB 0000000000000000 submitted while active drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528
Let's improve the current situation, by not re-submiting the urb if we are stopping the status event. Also process the queued work (if any) during stop.
CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_status_start() uvc_ctrl_status_event_work() -> FAIL
Hopefully, with the usb layer protection this should be enough to cover all the cases.
Cc: stable@vger.kernel.org Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ drivers/media/usb/uvc/uvc_status.c | 6 ++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 10 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index c95a2229f4fa..5160facc8e20 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1442,6 +1442,9 @@ static void uvc_ctrl_status_event_work(struct work_struct *work)
uvc_ctrl_status_event(w->chain, w->ctrl, w->data);
+ if (dev->flush_status) + return; + /* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret = usb_submit_urb(w->urb, GFP_KERNEL); diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 7518ffce22ed..09a5802dc974 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -304,10 +304,16 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags) if (dev->int_urb == NULL) return 0;
+ dev->flush_status = false; return usb_submit_urb(dev->int_urb, flags); }
void uvc_status_stop(struct uvc_device *dev) { + struct uvc_ctrl_work *w = &dev->async_ctrl; + + dev->flush_status = true; usb_kill_urb(dev->int_urb); + if (cancel_work_sync(&w->work)) + uvc_ctrl_status_event(w->chain, w->ctrl, w->data); } diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index df93db259312..6a9b72d6789e 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -560,6 +560,7 @@ struct uvc_device { struct usb_host_endpoint *int_ep; struct urb *int_urb; u8 *status; + bool flush_status; struct input_dev *input; char input_phys[64];
On Tue, Dec 13, 2022 at 11:36 PM Ricardo Ribalda ribalda@chromium.org wrote:
usb_kill_urb warranties that all the handlers are finished when it returns, but does not protect against threads that might be handling asynchronously the urb.
For UVC, the function uvc_ctrl_status_event_async() takes care of control changes asynchronously.
If the code is executed in the following order:
CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_ctrl_status_event_work() uvc_status_start() -> FAIL
Then uvc_status_start will keep failing and this error will be shown:
<4>[ 5.540139] URB 0000000000000000 submitted while active drivers/usb/core/urb.c:378 usb_submit_urb+0x4c3/0x528
Let's improve the current situation, by not re-submiting the urb if we are stopping the status event. Also process the queued work (if any) during stop.
CPU 0 CPU 1 ===== ===== uvc_status_complete() uvc_status_stop() uvc_status_start() uvc_ctrl_status_event_work() -> FAIL
Hopefully, with the usb layer protection this should be enough to cover all the cases.
Cc: stable@vger.kernel.org Fixes: e5225c820c05 ("media: uvcvideo: Send a control event when a Control Change interrupt arrives") Signed-off-by: Ricardo Ribalda ribalda@chromium.org
drivers/media/usb/uvc/uvc_ctrl.c | 3 +++ drivers/media/usb/uvc/uvc_status.c | 6 ++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 10 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c index c95a2229f4fa..5160facc8e20 100644 --- a/drivers/media/usb/uvc/uvc_ctrl.c +++ b/drivers/media/usb/uvc/uvc_ctrl.c @@ -1442,6 +1442,9 @@ static void uvc_ctrl_status_event_work(struct work_struct *work)
uvc_ctrl_status_event(w->chain, w->ctrl, w->data);
if (dev->flush_status)return;/* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret = usb_submit_urb(w->urb, GFP_KERNEL);diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 7518ffce22ed..09a5802dc974 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -304,10 +304,16 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags) if (dev->int_urb == NULL) return 0;
dev->flush_status = false; return usb_submit_urb(dev->int_urb, flags);}
void uvc_status_stop(struct uvc_device *dev) {
struct uvc_ctrl_work *w = &dev->async_ctrl;dev->flush_status = true; usb_kill_urb(dev->int_urb);if (cancel_work_sync(&w->work))uvc_ctrl_status_event(w->chain, w->ctrl, w->data);} diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index df93db259312..6a9b72d6789e 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -560,6 +560,7 @@ struct uvc_device { struct usb_host_endpoint *int_ep; struct urb *int_urb; u8 *status;
bool flush_status; struct input_dev *input; char input_phys[64];-- 2.39.0.rc1.256.g54fd8350bd-goog-b4-0.11.0-dev-696ae
Reviewed-by: Yunke Cao yunkec@chromium.org
UVC_MAX_STATUS_SIZE is 16, simplify the code by inlining dev->status.
Signed-off-by: Ricardo Ribalda ribalda@chromium.org --- drivers/media/usb/uvc/uvc_status.c | 9 +-------- drivers/media/usb/uvc/uvcvideo.h | 2 +- 2 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_status.c b/drivers/media/usb/uvc/uvc_status.c index 09a5802dc974..52999b3b7c48 100644 --- a/drivers/media/usb/uvc/uvc_status.c +++ b/drivers/media/usb/uvc/uvc_status.c @@ -259,15 +259,9 @@ int uvc_status_init(struct uvc_device *dev)
uvc_input_init(dev);
- dev->status = kzalloc(UVC_MAX_STATUS_SIZE, GFP_KERNEL); - if (dev->status == NULL) - return -ENOMEM; - dev->int_urb = usb_alloc_urb(0, GFP_KERNEL); - if (dev->int_urb == NULL) { - kfree(dev->status); + if (!dev->int_urb) return -ENOMEM; - }
pipe = usb_rcvintpipe(dev->udev, ep->desc.bEndpointAddress);
@@ -296,7 +290,6 @@ void uvc_status_unregister(struct uvc_device *dev) void uvc_status_cleanup(struct uvc_device *dev) { usb_free_urb(dev->int_urb); - kfree(dev->status); }
int uvc_status_start(struct uvc_device *dev, gfp_t flags) diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h index 6a9b72d6789e..ccc7e3b60bf1 100644 --- a/drivers/media/usb/uvc/uvcvideo.h +++ b/drivers/media/usb/uvc/uvcvideo.h @@ -559,7 +559,7 @@ struct uvc_device { /* Status Interrupt Endpoint */ struct usb_host_endpoint *int_ep; struct urb *int_urb; - u8 *status; + u8 status[UVC_MAX_STATUS_SIZE]; bool flush_status; struct input_dev *input; char input_phys[64];
Hi,
Thanks for your patch.
FYI: kernel test robot notices the stable kernel rule is not satisfied.
Rule: 'Cc: stable@vger.kernel.org' or 'commit <sha1> upstream.' Subject: [PATCH v2 2/2] media: uvcvideo: Do not alloc dev->status Link: https://lore.kernel.org/stable/20221212-uvc-race-v2-2-54496cc3b8ab%40chromiu...
The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
On (22/12/13 15:35), Ricardo Ribalda wrote: [..]
+++ b/drivers/media/usb/uvc/uvcvideo.h @@ -559,7 +559,7 @@ struct uvc_device { /* Status Interrupt Endpoint */ struct usb_host_endpoint *int_ep; struct urb *int_urb;
- u8 *status;
- u8 status[UVC_MAX_STATUS_SIZE];
Can we use `struct uvc_control_status status;` instead of open-coding it? Seems that this is what the code wants anyway:
struct uvc_control_status *status = (struct uvc_control_status *)dev->status;
And then we can drop casts in uvc_status_complete().
Hi Sergey
Thanks for the review
On Wed, 14 Dec 2022 at 01:40, Sergey Senozhatsky senozhatsky@chromium.org wrote:
On (22/12/13 15:35), Ricardo Ribalda wrote: [..]
+++ b/drivers/media/usb/uvc/uvcvideo.h @@ -559,7 +559,7 @@ struct uvc_device { /* Status Interrupt Endpoint */ struct usb_host_endpoint *int_ep; struct urb *int_urb;
u8 *status;
u8 status[UVC_MAX_STATUS_SIZE];Can we use `struct uvc_control_status status;` instead of open-coding it? Seems that this is what the code wants anyway:
It can also be a `struct uvc_streaming_status`
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv...
so we always need the casting :(
struct uvc_control_status *status = (struct uvc_control_status *)dev->status;And then we can drop casts in uvc_status_complete().
On (22/12/14 06:57), Ricardo Ribalda wrote:
On (22/12/13 15:35), Ricardo Ribalda wrote: [..]
+++ b/drivers/media/usb/uvc/uvcvideo.h @@ -559,7 +559,7 @@ struct uvc_device { /* Status Interrupt Endpoint */ struct usb_host_endpoint *int_ep; struct urb *int_urb;
u8 *status;
u8 status[UVC_MAX_STATUS_SIZE];Can we use `struct uvc_control_status status;` instead of open-coding it? Seems that this is what the code wants anyway:
It can also be a `struct uvc_streaming_status`
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/driv...
so we always need the casting :(
Then perhaps we can put both of them into anon union in struct uvc_device as stream_status and control_status?
linux-stable-mirror@lists.linaro.org
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Ricardo Ribalda -
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Yunke Cao