Re: Locking issues w/ functionfs gadget and aio?

Al Viro
2015-06-21T05:24:48Z

On Fri, Jun 12, 2015 at 05:51:12PM -0700, John Stultz wrote:

> I'm not super sure what the right fix is, but if do something like the
> following (sorry, whitespace corrupted via copy/paste), I don't seem
> to run into the problem.

Looks sane. Which tree would you prefer it to go through, vfs or usb?
BTW, in either case you'd need Signed-off-by: on that patch...

> diff --git a/drivers/usb/gadget/function/f_fs.c
> b/drivers/usb/gadget/function/f_fs.c
> index 3507f88..e322818 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -924,7 +924,8 @@ static ssize_t ffs_epfile_write_iter(struct kiocb
> *kiocb, struct iov_iter *from)
>
> kiocb->private = p;
>
> - kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
> + if (p->aio)
> + kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
>
> res = ffs_epfile_io(kiocb->ki_filp, p);
> if (res == -EIOCBQUEUED)
> @@ -968,7 +969,8 @@ static ssize_t ffs_epfile_read_iter(struct kiocb
> *kiocb, struct iov_iter *to)
>
> kiocb->private = p;
>
> - kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
> + if(p->aio)
> + kiocb_set_cancel_fn(kiocb, ffs_aio_cancel);
>
> res = ffs_epfile_io(kiocb->ki_filp, p);
> if (res == -EIOCBQUEUED)
>
>
> Is there a better solution here? I'm not sure I see if the
> is_sync_kiocb(kiocb) check would ever be false from here, so I'm not
> sure if all the p->aio checking is really needed or not.
>
> This issue seems to have been introduced with 70e60d917e91fff
> (gadget/function/f_fs.c: switch to ->{read,write}_iter())
>
> thanks
> -john
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
Please read the FAQ at http://www.tux.org/lkml/