Re: Query regarding "firmware: arm_scmi: Free mailbox channels if probe fails"

Cristian Marussi
2022-09-22T15:29:08Z

On Thu, Sep 22, 2022 at 03:54:31PM +0100, Cristian Marussi wrote:
> On Thu, Sep 22, 2022 at 10:31:47AM +0530, Shivnandan Kumar wrote:
> > Hi Christian,
> >
>

Hi Shivnandan,

[snip]

> Looking at the transport layer that you use, mailbox, I see that while
> setup/free helpers are synchronized on an internal chan->lock, the RX
> path inside the mailbox core is not, so I tried this:
>
>
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index 4229b9b5da98..bb6173c0ad54 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -157,9 +157,13 @@ static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
> */
> void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
> {
> + unsigned long flags;
> +
> + spin_lock_irqsave(&chan->lock, flags);
> /* No buffering the received data */
> if (chan->cl->rx_callback)
> chan->cl->rx_callback(chan->cl, mssg);
> + spin_unlock_irqrestore(&chan->lock, flags);
> }
> EXPORT_SYMBOL_GPL(mbox_chan_received_data);
>

...sorry... a small change on the tentative above fix...

----8<------

diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 4229b9b5da98..6fbe183acdae 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -157,9 +157,13 @@ static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer)
*/
void mbox_chan_received_data(struct mbox_chan *chan, void *mssg)
{
+ unsigned long flags;
+
+ spin_lock_irqsave(&chan->lock, flags);
/* No buffering the received data */
- if (chan->cl->rx_callback)
+ if (chan->cl && chan->cl->rx_callback)
chan->cl->rx_callback(chan->cl, mssg);
+ spin_unlock_irqrestore(&chan->lock, flags);
}
EXPORT_SYMBOL_GPL(mbox_chan_received_data);

------8<-----

Thanks,
Cristian