RE: [PATCH net-next v9 2/2] net: ethernet: Add driver for Sunplus SP7021

["Wells Lu 呂芳騰" <wells.lu@sunplus.com>]

Hi Francois,


> [...]
> > +int spl2sw_rx_poll(struct napi_struct *napi, int budget) {
> [...]
> > +	wmb();	/* make sure settings are effective. */
> > +	mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +	mask &= ~MAC_INT_RX;
> > +	writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +
> > +	napi_complete(napi);
> > +	return 0;
> > +}
> > +
> > +int spl2sw_tx_poll(struct napi_struct *napi, int budget) {
> [...]
> > +	wmb();			/* make sure settings are effective. */
> > +	mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +	mask &= ~MAC_INT_TX;
> > +	writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +
> > +	napi_complete(napi);
> > +	return 0;
> > +}
> > +
> > +irqreturn_t spl2sw_ethernet_interrupt(int irq, void *dev_id) {
> [...]
> > +	if (status & MAC_INT_RX) {
> > +		/* Disable RX interrupts. */
> > +		mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +		mask |= MAC_INT_RX;
> > +		writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> [...]
> > +		napi_schedule(&comm->rx_napi);
> > +	}
> > +
> > +	if (status & MAC_INT_TX) {
> > +		/* Disable TX interrupts. */
> > +		mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +		mask |= MAC_INT_TX;
> > +		writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
> > +
> > +		if (unlikely(status & MAC_INT_TX_DES_ERR)) {
> [...]
> > +		} else {
> > +			napi_schedule(&comm->tx_napi);
> > +		}
> > +	}
> 
> The readl/writel sequence in rx_poll (or tx_poll) races with the irq handler performing
> MAC_INT_TX (or MAC_INT_RX) work. If the readl returns the same value to both callers,
> one of the writel will be overwritten.
> 
> --
> Ueimor

I will add disable_irq() and enable_irq() for spl2sw_rx_poll() and spl2sw_tx_poll() as shown below:

spl2sw_rx_poll():

	wmb();	/* make sure settings are effective. */
	disable_irq(comm->irq);
	mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
	mask &= ~MAC_INT_RX;
	writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
	enable_irq(comm->irq);

spl2sw_tx_poll():

	wmb();			/* make sure settings are effective. */
	disable_irq(comm->irq);
	mask = readl(comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
	mask &= ~MAC_INT_TX;
	writel(mask, comm->l2sw_reg_base + L2SW_SW_INT_MASK_0);
	enable_irq(comm->irq);


Is the modification ok?


Thank you for your review.

Best regards,
Wells