On Sat, Sep 03, 2022 at 08:49:56AM +0100, Sean Young wrote:
> On Fri, Sep 02, 2022 at 11:42:41PM +0530, Gautam Menghani wrote:
> > On Sun, Aug 14, 2022 at 07:55:42PM +0530, Gautam Menghani wrote:
> > > The warning "URB submitted while active" is reported if the function
> > > send_packet() in imon.c is called if a write is already is in progress.
> > > Add a check to return -EBUSY in case a write is already is in progress.
> > > Also, mark tx.busy as false after transmission is completed.
> > >
> > > Fixes: 21677cfc562a ("V4L/DVB: ir-core: add imon driver")
> > > Cc: hdanton@xxxxxxxx
> > > Suggested-by: hdanton@xxxxxxxx
> > > Link: https://syzkaller.appspot.com/bug?id=e378e6a51fbe6c5cc43e34f131cc9a315ef0337e
> > > Reported-by: syzbot+0c3cb6dc05fbbdc3ad66@xxxxxxxxxxxxxxxxxxxxxxxxx
> > > Signed-off-by: Gautam Menghani <gautammenghani201@xxxxxxxxx>
> > > ---
> > > drivers/media/rc/imon.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/media/rc/imon.c b/drivers/media/rc/imon.c
> > > index 735b925da998..a5b997c2c7e2 100644
> > > --- a/drivers/media/rc/imon.c
> > > +++ b/drivers/media/rc/imon.c
> > > @@ -598,6 +598,8 @@ static int send_packet(struct imon_context *ictx)
> > > int retval = 0;
> > > struct usb_ctrlrequest *control_req = NULL;
> > >
> > > + if (ictx->tx.busy)
> > > + return -EBUSY;
> > > /* Check if we need to use control or interrupt urb */
> > > if (!ictx->tx_control) {
> > > pipe = usb_sndintpipe(ictx->usbdev_intf0,
> > > @@ -654,6 +656,7 @@ static int send_packet(struct imon_context *ictx)
> > > pr_err_ratelimited("task interrupted\n");
> > > }
> > > mutex_lock(&ictx->lock);
> > > + ictx->tx.busy = false;
> > >
> > > retval = ictx->tx.status;
> > > if (retval)
> > > --
> > > 2.34.1
> > >
> > Hi,
> >
> > Please review the above fix and let me know if any changes are needed.
>
> Greg has pointed out issues with this patch: there is no locking.
>
> Thanks,
>
> Sean
Hi,
I am a bit confused about the locking part. All the calls to send_packet() are
made with ictx->lock held. So will the following be sufficient?
lockdep_assert_held(&ictx->lock);
if (ictx->tx.busy)
return -EBUSY;
Or do we need to add a mutex/spin lock inside ictx->tx structure?
Or should we instead wait for the the tx to be completed as follows:
wait_for_completion(&ictx->tx.finished);
Please advise.
Thanks,
Gautam
