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SubjectRe: [PATCH v2 2/2] net: mvneta: improve suspend/resume
On Fri, Mar 30, 2018 at 06:36:15PM +0800, Jisheng Zhang wrote:
> Current suspend/resume implementation reuses the mvneta_open() and
> mvneta_close(), but it could be optimized to take only necessary
> actions during suspend/resume.
>
> One obvious problem of current implementation is: after hundreds of
> system suspend/resume cycles, the resume of mvneta could fail due to
> fragmented dma coherent memory. After this patch, the non-necessary
> memory alloc/free is optimized out.

I don't think you've properly tested this. Please ensure that you test
patches with the appropriate debug options enabled.

> @@ -4586,16 +4586,43 @@ static int mvneta_remove(struct platform_device *pdev)
> #ifdef CONFIG_PM_SLEEP
> static int mvneta_suspend(struct device *device)
> {
> + int queue;
> struct net_device *dev = dev_get_drvdata(device);
> struct mvneta_port *pp = netdev_priv(dev);
>
> - rtnl_lock();
> - if (netif_running(dev))
> - mvneta_stop(dev);
> - rtnl_unlock();
...
> + mvneta_stop_dev(pp);

You're removing the rtnl_lock() that I introduced in 3b8bc67413de
("net: mvneta: ensure PM paths take the rtnl lock") which is necessary
to provide phylink with consistent locking. mvneta_stop_dev() calls
phylink_stop() which will check that the rtnl lock is held, and will
print a warning if it isn't.

Your patch will cause a regression here.

> +
> + for (queue = 0; queue < rxq_number; queue++) {
> + struct mvneta_rx_queue *rxq = &pp->rxqs[queue];
> +
> + mvneta_rxq_drop_pkts(pp, rxq);
> + }
> +
> + for (queue = 0; queue < txq_number; queue++) {
> + struct mvneta_tx_queue *txq = &pp->txqs[queue];
> +
> + mvneta_txq_hw_deinit(pp, txq);
> + }
> +
> +clean_exit:
> netif_device_detach(dev);
> clk_disable_unprepare(pp->clk_bus);
> clk_disable_unprepare(pp->clk);
> +
> return 0;
> }
>
> @@ -4604,7 +4631,7 @@ static int mvneta_resume(struct device *device)
> struct platform_device *pdev = to_platform_device(device);
> struct net_device *dev = dev_get_drvdata(device);
> struct mvneta_port *pp = netdev_priv(dev);
> - int err;
> + int err, queue;
>
> clk_prepare_enable(pp->clk);
> if (!IS_ERR(pp->clk_bus))
> @@ -4626,12 +4653,36 @@ static int mvneta_resume(struct device *device)
> }
>
> netif_device_attach(dev);
> - rtnl_lock();
> - if (netif_running(dev)) {
> - mvneta_open(dev);
> - mvneta_set_rx_mode(dev);
...
> }
> - rtnl_unlock();
...
> + mvneta_start_dev(pp);

Same applies here.

--
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