Re: CM-ITC, pch_can/c_can_pci, sendto() returning ENOBUFS

[dariobin@libero.it]

Hi Michael,

> Il 23/09/2022 13:36 Marc Kleine-Budde <mkl@pengutronix.de> ha scritto:
> 
>  
> On 16.09.2022 06:14:58, Jacob Kroon wrote:
> > What I do know is that if I revert commit:
> > 
> > "can: c_can: cache frames to operate as a true FIFO"
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=387da6bc7a826cc6d532b1c0002b7c7513238d5f
> > 
> > then everything looks good. I don't get any BUG messages, and the host
> > has been running overnight without problems, so it seems to have fixed
> > the network interface lockup as well.
> 
> Jacob, after this mail, I'll send 2 patches. One tries to disable the
> cache feature for C_CAN cores, the other shuts a potential race window.

About the "can: c_can: don't cache TX messages for C_CAN cores" patch:
Could it make sense to change the c_can_start_xmit in this way

-       if (idx < c_can_get_tx_tail(tx_ring))
-               cmd &= ~IF_COMM_TXRQST; /* Cache the message */
+       if (idx < c_can_get_tx_tail(tx_ring)) {
+               if (priv->type == BOSCH_D_CAN) {
+                       cmd &= ~IF_COMM_TXRQST; /* Cache the message */
+               } else {
+                       netif_stop_queue(priv->dev);
+                       return NETDEV_TX_BUSY;
+               }
+       }

without changing the c_can_get_tx_{free,busy} routines ?

Thanks and regards,
Dario

> Please test both patches, but only apply one of them at a time. :)
> 
> regards,
> Marc
> 
> -- 
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