From: Al Viro <viro@ZenIV.linux.org.uk>
To: John Stultz <john.stultz@linaro.org>
Cc: Felipe Balbi <balbi@ti.com>,
Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
Krzysztof Opasiak <k.opasiak@samsung.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Michal Nazarewicz <mina86@mina86.com>,
Robert Baldyga <r.baldyga@samsung.com>,
lkml <linux-kernel@vger.kernel.org>,
linux-usb@vger.kernel.org
Subject: Re: Locking issues w/ functionfs gadget and aio?
Date: Sun, 21 Jun 2015 06:24:30 +0100 [thread overview]
Message-ID: <20150621052430.GA27824@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CALAqxLXPWhQvWfqrpw0MVygothMKhE++cPMj2ZjoZR7KVPwYXQ@mail.gmail.com>
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
> --
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next prev parent reply other threads:[~2015-06-21 5:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-09 1:14 Locking issues w/ functionfs gadget and aio? John Stultz
2015-06-13 0:51 ` John Stultz
2015-06-21 5:24 ` Al Viro [this message]
2015-06-22 17:20 ` John Stultz
2015-07-01 9:59 ` Andrzej Pietrasiewicz
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