Hi,
(it helps if you Cc the maintainer too :-)
On Tue, Mar 31, 2015 at 07:53:39PM +0100, Baxter, Jim wrote:
> I have been looking at an issue where a phone that is the Function FS
> host sometimes locks up and causes the function:
which USB controller ? which kernel ? which platform ?
> static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data
> *io_data) in drivers/usb/gadget/function/f_fs.c to timeout after
> MAX_SCHEDULE_TIMEOUT jiffies.
yeah, that's pretty much "never timeout" :-)
> We are opening the ffs connection with the O_NONBLOCK option and this
> timeout seems to be far too long.
is this your own application ? How can I make sure it's correct ?
> The code causing the wait is here (line 834):
>
> if (unlikely(ret < 0)) {
> /* nop */
> } else if (unlikely(
> wait_for_completion_interruptible(&done))) {
right, this is waiting for the previous usb_ep_queue() to complete. Why
hasn't it completed yet ? Do you have a USB sniffer to check if data has
passed over the wire ? Did the host shifted any token in the wire trying
to move data around ?
> ret = -EINTR;
> usb_ep_dequeue(ep->ep, req);
> } else {
>
> The function call wait_for_completion_interruptible(&done) equates to:
> wait_for_completion_interruptible_timeout(&done, MAX_SCHEDULE_TIMEOUT);
>
>
> I was wondering what to change to fix this, is it reasonable to use a
> very small timeout if it is O_NONBLOCK or is any blocking not allowed?
>
> I would appreciate any thoughts on how this should work?
sounds like a bug on your USB peripheral controller driver. Which one is
that ? Again, which kernel ? Where are the logs ?
regards
--
balbi
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