Re: [PATCH v3 3/4] bus: mhi: host: Avoid processing buffer and event of a disable channel

[Qiang Yu]

On 11/10/2023 11:38 AM, Qiang Yu wrote:
> On 11/10/2023 12:32 AM, Manivannan Sadhasivam wrote:
> > On Tue, Nov 07, 2023 at 03:16:04PM +0800, Qiang Yu wrote:
> > > Ckeck mhi channel state after getting chan->lock to ensure that we only
> > > queue buffer to an enabled channel and process event of an enabled 
> > > channel.
> > This commit message doesn't give proper explanation on how the 
> > channel can go to
> > disabled state in between parse_xfer_event() and mhi_gen_tre().
> >
> > - Mani
>
> Hi Mani. How about following commit message
>
> MHI channel state is protected by mhi_chan->lock. Hence, after core drops
> mhi_chan->lock during processing xfer event, it can not prevent channel
> state being changed if client closes channel or driver is removed at this
> time. So let's check mhi channel state after getting chan->lock again 
> to avoid
> queuing buffer to a disabled channel in xfer callback and stop processing
> event of the disabled channel.
Hi Mani, Have updated this commit message in V4 patch, hope get your 
comments.
> > > Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
> > > ---
> > >   drivers/bus/mhi/host/main.c | 4 ++++
> > >   1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> > > index a236dc2..b137d54 100644
> > > --- a/drivers/bus/mhi/host/main.c
> > > +++ b/drivers/bus/mhi/host/main.c
> > > @@ -672,6 +672,8 @@ static int parse_xfer_event(struct 
> > > mhi_controller *mhi_cntrl,
> > >               }
> > >                 read_lock_bh(&mhi_chan->lock);
> > > +            if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
> > > +                goto end_process_tx_event;
> > >           }
> > >           break;
> > >       } /* CC_EOT */
> > > @@ -1211,6 +1213,8 @@ int mhi_gen_tre(struct mhi_controller 
> > > *mhi_cntrl, struct mhi_chan *mhi_chan,
> > >         /* Protect accesses for reading and incrementing WP */
> > >       write_lock_bh(&mhi_chan->lock);
> > > +    if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
> > > +        return -EINVAL;
> > >         buf_ring = &mhi_chan->buf_ring;
> > >       tre_ring = &mhi_chan->tre_ring;
> > > --
> > > 2.7.4