netdev - [PATCH v2] net: pxa168_eth: add netconsole support

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Message-ID: <alpine.LNX.2.20.13.1802012234510.5946@monopod.intra.ispras.ru>
Date:   Thu, 1 Feb 2018 22:45:17 +0300 (MSK)
From:   Alexander Monakov <amonakov@...ras.ru>
To:     David Miller <davem@...emloft.net>
cc:     netdev@...r.kernel.org, rmk+kernel@....linux.org.uk,
        sebastian.hesselbarth@...il.com, f.fainelli@...il.com
Subject: [PATCH v2] net: pxa168_eth: add netconsole support

This implements ndo_poll_controller callback which is necessary to
enable netconsole.

Signed-off-by: Alexander Monakov <amonakov@...ras.ru>
Cc: Russell King <rmk+kernel@....linux.org.uk>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Cc: Florian Fainelli <f.fainelli@...il.com>
---

Here's the revised patch that performs interrupt disabling correctly
as far as I can tell. It's still unclear to me why some drivers use
local_irq_save/restore:

1. netconsole must have already disabled local interrupts, and netpoll
   verifies that; so local_irq_save in ndo_poll_controller must be a nop.

2. local disabling does not ensure that we wouldn't race with the irq
   handler in progress on some other cpu (but disable_irq does).

Please let me know if I'm missing something.

Thanks.
Alexander

 drivers/net/ethernet/marvell/pxa168_eth.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/ethernet/marvell/pxa168_eth.c b/drivers/net/ethernet/marvell/pxa168_eth.c
index 7bbd86f08e5f..3a9730612a70 100644
--- a/drivers/net/ethernet/marvell/pxa168_eth.c
+++ b/drivers/net/ethernet/marvell/pxa168_eth.c
@@ -1362,6 +1362,15 @@ static int pxa168_eth_do_ioctl(struct net_device *dev, struct ifreq *ifr,
 	return -EOPNOTSUPP;
 }
 
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void pxa168_eth_netpoll(struct net_device *dev)
+{
+	disable_irq(dev->irq);
+	pxa168_eth_int_handler(dev->irq, dev);
+	enable_irq(dev->irq);
+}
+#endif
+
 static void pxa168_get_drvinfo(struct net_device *dev,
 			       struct ethtool_drvinfo *info)
 {
@@ -1390,6 +1399,9 @@ static const struct net_device_ops pxa168_eth_netdev_ops = {
 	.ndo_do_ioctl		= pxa168_eth_do_ioctl,
 	.ndo_change_mtu		= pxa168_eth_change_mtu,
 	.ndo_tx_timeout		= pxa168_eth_tx_timeout,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller    = pxa168_eth_netpoll,
+#endif
 };
 
 static int pxa168_eth_probe(struct platform_device *pdev)
-- 
2.11.0