FAILED: patch "[PATCH] media: uvcvideo: Fix race condition with usb_kill_urb" failed to apply to 6.1-stable tree
Subsystems (3)
[email protected]
maintainerThe patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 619d9b710cf06f7a00a17120ca92333684ac45a8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
619d9b710cf0 ("media: uvcvideo: Fix race condition with usb_kill_urb") 40140eda661e ("media: uvcvideo: Implement mask for V4L2_CTRL_TYPE_MENU") adfd3910c27f ("media: uvcvideo: Remove void casting for the status endpoint")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 619d9b710cf06f7a00a17120ca92333684ac45a8 Mon Sep 17 00:00:00 2001
From: Ricardo Ribalda <[email protected]>
Date: Thu, 5 Jan 2023 15:31:29 +0100
Subject: [PATCH] media: uvcvideo: Fix race condition with usb_kill_urb
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.
drivers/media/usb/uvc/uvc_ctrl.c +5 -0
@@ -6,6 +6,7 @@* Laurent Pinchart ([email protected]) */ +#include <asm/barrier.h> #include <linux/bitops.h> #include <linux/kernel.h> #include <linux/list.h>
@@ -1571,6 +1572,10 @@ static void uvc_ctrl_status_event_work(struct work_struct *work)uvc_ctrl_status_event (w->chain, w->ctrl, w->data); +/* The barrier is needed to synchronize with uvc_status_stop(). */ +if (smp_load_acquire (&dev->flush_status)) +return ; +/* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret =usb_submit_urb (w->urb,GFP_KERNEL );
drivers/media/usb/uvc/uvc_status.c +37 -0
@@ -6,6 +6,7 @@* Laurent Pinchart ([email protected]) */ +#include <asm/barrier.h> #include <linux/kernel.h> #include <linux/input.h> #include <linux/slab.h>
@@ -311,5 +312,41 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags)void uvc_status_stop (struct uvc_device *dev) { +struct uvc_ctrl_work *w = &dev->async_ctrl; + +/* +* Prevent the asynchronous control handler from requeing the URB. The +* barrier is needed so the flush_status change is visible to other +* CPUs running the asynchronous handler before usb_kill_urb() is +* called below. +*/ +smp_store_release (&dev->flush_status, true); + +/* +* Cancel any pending asynchronous work. If any status event was queued, +* process it synchronously. +*/ +if (cancel_work_sync (&w->work)) +uvc_ctrl_status_event (w->chain, w->ctrl, w->data); + +/* Kill the urb. */ usb_kill_urb (dev->int_urb); + +/* +* The URB completion handler may have queued asynchronous work. This +* won't resubmit the URB as flush_status is set, but it needs to be +* cancelled before returning or it could then race with a future +* uvc_status_start() call. +*/ +if (cancel_work_sync (&w->work)) +uvc_ctrl_status_event (w->chain, w->ctrl, w->data); + +/* +* From this point, there are no events on the queue and the status URB +* is dead. No events will be queued until uvc_status_start() is called. +* The barrier is needed to make sure that flush_status is visible to +* uvc_ctrl_status_event_work() when uvc_status_start() will be called +* again. +*/ +smp_store_release (&dev->flush_status, false); }
drivers/media/usb/uvc/uvcvideo.h +1 -0
@@ -577,6 +577,7 @@ struct uvc_device {struct usb_host_endpoint *int_ep;struct urb *int_urb;struct uvc_status *status; +bool flush_status;struct input_dev *input;char input_phys[64 ];
PATCH 1/1 media: uvcvideo: Fix race condition with usb_kill_urb
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.
--- drivers/media/usb/uvc/uvc_ctrl.c | 5 ++++ drivers/media/usb/uvc/uvc_status.c | 37 ++++++++++++++++++++++++++++++ drivers/media/usb/uvc/uvcvideo.h | 1 + 3 files changed, 43 insertions(+)
drivers/media/usb/uvc/uvc_ctrl.c +5 -0
@@ -6,6 +6,7 @@* Laurent Pinchart ([email protected]) */ +#include <asm/barrier.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/module.h>
@@ -1442,6 +1443,10 @@ static void uvc_ctrl_status_event_work(struct work_struct *work)uvc_ctrl_status_event (w->chain, w->ctrl, w->data); +/* The barrier is needed to synchronize with uvc_status_stop(). */ +if (smp_load_acquire (&dev->flush_status)) +return ; +/* Resubmit the URB. */ w->urb->interval = dev->int_ep->desc.bInterval; ret =usb_submit_urb (w->urb,GFP_KERNEL );
drivers/media/usb/uvc/uvc_status.c +37 -0
@@ -6,6 +6,7 @@* Laurent Pinchart ([email protected]) */ +#include <asm/barrier.h> #include <linux/kernel.h> #include <linux/input.h> #include <linux/slab.h>
@@ -309,5 +310,41 @@ int uvc_status_start(struct uvc_device *dev, gfp_t flags)void uvc_status_stop (struct uvc_device *dev) { +struct uvc_ctrl_work *w = &dev->async_ctrl; + +/* +* Prevent the asynchronous control handler from requeing the URB. The +* barrier is needed so the flush_status change is visible to other +* CPUs running the asynchronous handler before usb_kill_urb() is +* called below. +*/ +smp_store_release (&dev->flush_status, true); + +/* +* Cancel any pending asynchronous work. If any status event was queued, +* process it synchronously. +*/ +if (cancel_work_sync (&w->work)) +uvc_ctrl_status_event (w->chain, w->ctrl, w->data); + +/* Kill the urb. */ usb_kill_urb (dev->int_urb); + +/* +* The URB completion handler may have queued asynchronous work. This +* won't resubmit the URB as flush_status is set, but it needs to be +* cancelled before returning or it could then race with a future +* uvc_status_start() call. +*/ +if (cancel_work_sync (&w->work)) +uvc_ctrl_status_event (w->chain, w->ctrl, w->data); + +/* +* From this point, there are no events on the queue and the status URB +* is dead. No events will be queued until uvc_status_start() is called. +* The barrier is needed to make sure that flush_status is visible to +* uvc_ctrl_status_event_work() when uvc_status_start() will be called +* again. +*/ +smp_store_release (&dev->flush_status, false); }
drivers/media/usb/uvc/uvcvideo.h +1 -0
@@ -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 ];
Signature · 1 line
2.40.0.rc0.216.gc4246ad0f0-goog