Re: [PATCH] usb: musb: Get the musb_qh poniter after musb_giveback

[xingxing luo]

Add more.

On Mon, Sep 18, 2023 at 1:22 PM xingxing luo <xingxing0070.luo@xxxxxxxxx> wrote:
>
> On Fri, Sep 15, 2023 at 4:48 PM Sergey Shtylyov <s.shtylyov@xxxxxx> wrote:
> >
> > On 9/15/23 5:59 AM, xingxing luo wrote:
> > [...]
> >
> > >>> When multiple threads are performing USB transmission, musb->lock will be
> > >>> unlocked when musb_giveback is executed. At this time, qh may be released
> > >>> in the dequeue process in other threads, resulting in a wild pointer, so
> > >>> it needs to be here get qh again, and judge whether qh is NULL, and when
> > >>> dequeue, you need to set qh to NULL.
> > >>>
> > >>> Fixes: dbac5d07d13e ("usb: musb: host: don't start next rx urb if current one failed")
> > >>> Signed-off-by: Xingxing Luo <xingxing.luo@xxxxxxxxxx>
> > >>> ---
> > >>>  drivers/usb/musb/musb_host.c | 9 ++++++++-
> > >>>  1 file changed, 8 insertions(+), 1 deletion(-)
> > >>>
> > >>> diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
> > >>> index a02c29216955..9df27db5847a 100644
> > >>> --- a/drivers/usb/musb/musb_host.c
> > >>> +++ b/drivers/usb/musb/musb_host.c
> > >>> @@ -321,10 +321,16 @@ static void musb_advance_schedule(struct musb *musb, struct urb *urb,
> > >>>       musb_giveback(musb, urb, status);
> > >>>       qh->is_ready = ready;
> > >>>
> > >>> +     /*
> > >>> +      * musb->lock had been unlocked in musb_giveback, so somtimes qh
> > >>
> > >>    Sometimes?
> >
> >    You have a typo...
> >
> > >>
> > >>> +      * may freed, need get it again
> > >>> +      */
> > >>> +     qh = musb_ep_get_qh(hw_ep, is_in);
> > >>> +
> > >>>       /* reclaim resources (and bandwidth) ASAP; deschedule it, and
> > >>>        * invalidate qh as soon as list_empty(&hep->urb_list)
> > >>>        */
> > >>> -     if (list_empty(&qh->hep->urb_list)) {
> > >>> +     if (qh != NULL && list_empty(&qh->hep->urb_list)) {
> > >>
> > >>    Just qh, perhaps?
> > >
> > > Could you elaborate a little more?
> > > Thanks.
> >
> >    Just 'qh' gives you the same as 'qh != NULL'.
>
> Ok, I will address this in the next version.
>
> >
> > [...]
> >
> > MBR, Sergey

B.R Xingxing.Luo