[v2,1/3] usb: raw-gadget: properly handle interrupted requests
Commit Message
From: Andrey Konovalov <andreyknvl@gmail.com>
Currently, if a USB request that was queued by Raw Gadget is interrupted
(via a signal), wait_for_completion_interruptible returns -ERESTARTSYS.
Raw Gadget then attempts to propagate this value to userspace as a return
value from its ioctls. However, when -ERESTARTSYS is returned by a syscall
handler, the kernel internally restarts the syscall.
This doesn't allow userspace applications to interrupt requests queued by
Raw Gadget (which is required when the emulated device is asked to switch
altsettings). It also violates the implied interface of Raw Gadget that a
single ioctl must only queue a single USB request.
Instead, make Raw Gadget do what GadgetFS does: check whether the request
was interrupted (dequeued with status == -ECONNRESET) and report -EINTR to
userspace.
Fixes: f2c2e717642c ("usb: gadget: add raw-gadget interface")
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
---
drivers/usb/gadget/legacy/raw_gadget.c | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)
Comments
On Thu, Oct 26, 2023 at 10:01:12PM +0200, andrey.konovalov@linux.dev wrote:
> From: Andrey Konovalov <andreyknvl@gmail.com>
>
> Currently, if a USB request that was queued by Raw Gadget is interrupted
> (via a signal), wait_for_completion_interruptible returns -ERESTARTSYS.
> Raw Gadget then attempts to propagate this value to userspace as a return
> value from its ioctls. However, when -ERESTARTSYS is returned by a syscall
> handler, the kernel internally restarts the syscall.
>
> This doesn't allow userspace applications to interrupt requests queued by
> Raw Gadget (which is required when the emulated device is asked to switch
> altsettings). It also violates the implied interface of Raw Gadget that a
> single ioctl must only queue a single USB request.
>
> Instead, make Raw Gadget do what GadgetFS does: check whether the request
> was interrupted (dequeued with status == -ECONNRESET) and report -EINTR to
> userspace.
>
> Fixes: f2c2e717642c ("usb: gadget: add raw-gadget interface")
> Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
> ---
Hi,
This is the friendly patch-bot of Greg Kroah-Hartman. You have sent him
a patch that has triggered this response. He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created. Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.
You are receiving this message because of the following common error(s)
as indicated below:
- You have marked a patch with a "Fixes:" tag for a commit that is in an
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signed-off-by area at all, which means that the patch will not be
applied to any older kernel releases. To properly fix this, please
follow the documented rules in the
Documentation/process/stable-kernel-rules.rst file for how to resolve
this.
If you wish to discuss this problem further, or you have questions about
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Greg will reply once he has dug out from the pending patches received
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thanks,
greg k-h's patch email bot
@@ -674,12 +674,12 @@ static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
if (WARN_ON(in && dev->ep0_out_pending)) {
ret = -ENODEV;
dev->state = STATE_DEV_FAILED;
- goto out_done;
+ goto out_unlock;
}
if (WARN_ON(!in && dev->ep0_in_pending)) {
ret = -ENODEV;
dev->state = STATE_DEV_FAILED;
- goto out_done;
+ goto out_unlock;
}
dev->req->buf = data;
@@ -694,7 +694,7 @@ static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
"fail, usb_ep_queue returned %d\n", ret);
spin_lock_irqsave(&dev->lock, flags);
dev->state = STATE_DEV_FAILED;
- goto out_done;
+ goto out_queue_failed;
}
ret = wait_for_completion_interruptible(&dev->ep0_done);
@@ -703,13 +703,16 @@ static int raw_process_ep0_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
usb_ep_dequeue(dev->gadget->ep0, dev->req);
wait_for_completion(&dev->ep0_done);
spin_lock_irqsave(&dev->lock, flags);
- goto out_done;
+ if (dev->ep0_status == -ECONNRESET)
+ dev->ep0_status = -EINTR;
+ goto out_interrupted;
}
spin_lock_irqsave(&dev->lock, flags);
- ret = dev->ep0_status;
-out_done:
+out_interrupted:
+ ret = dev->ep0_status;
+out_queue_failed:
dev->ep0_urb_queued = false;
out_unlock:
spin_unlock_irqrestore(&dev->lock, flags);
@@ -1078,7 +1081,7 @@ static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
"fail, usb_ep_queue returned %d\n", ret);
spin_lock_irqsave(&dev->lock, flags);
dev->state = STATE_DEV_FAILED;
- goto out_done;
+ goto out_queue_failed;
}
ret = wait_for_completion_interruptible(&done);
@@ -1087,13 +1090,16 @@ static int raw_process_ep_io(struct raw_dev *dev, struct usb_raw_ep_io *io,
usb_ep_dequeue(ep->ep, ep->req);
wait_for_completion(&done);
spin_lock_irqsave(&dev->lock, flags);
- goto out_done;
+ if (ep->status == -ECONNRESET)
+ ep->status = -EINTR;
+ goto out_interrupted;
}
spin_lock_irqsave(&dev->lock, flags);
- ret = ep->status;
-out_done:
+out_interrupted:
+ ret = ep->status;
+out_queue_failed:
ep->urb_queued = false;
out_unlock:
spin_unlock_irqrestore(&dev->lock, flags);