diff mbox series

[v4,net-next,07/18] parisc/led: hold the netdev lists lock when retrieving device statistics

Message ID 20210108002005.3429956-8-olteanv@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series Make .ndo_get_stats64 sleepable | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers fail 3 maintainers not CCed: linux-parisc@vger.kernel.org deller@gmx.de James.Bottomley@HansenPartnership.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 45 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Vladimir Oltean Jan. 8, 2021, 12:19 a.m. UTC 
From: Vladimir Oltean <vladimir.oltean@nxp.com>

In the effort of making .ndo_get_stats64 be able to sleep, we need to
ensure the callers of dev_get_stats do not use atomic context.

The LED driver for HP-PARISC workstations uses a workqueue to
periodically check for updates in network interface statistics, and
flicker when those have changed (i.e. there has been activity on the
line). Ignoring the fact that this driver is completely duplicating
drivers/leds/trigger/ledtrig-netdev.c, there is an even bigger problem.
Now, the dev_get_stats call can sleep, and iterating through the list of
network interfaces still needs to ensure the integrity of list of
network interfaces. So that leaves us only one locking option given the
current design of the network stack, and that is the netns mutex.

Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
Changes in v4:
None.

Changes in v3:
None.

Changes in v2:
None.

 drivers/parisc/led.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c
index 3cada632a4be..c8c6b2301dc9 100644
--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -38,7 +38,6 @@ 
 #include <linux/ctype.h>
 #include <linux/blkdev.h>
 #include <linux/workqueue.h>
-#include <linux/rcupdate.h>
 #include <asm/io.h>
 #include <asm/processor.h>
 #include <asm/hardware.h>
@@ -355,25 +354,29 @@  static __inline__ int led_get_net_activity(void)
 	int retval;
 
 	rx_total = tx_total = 0;
-	
-	/* we are running as a workqueue task, so we can use an RCU lookup */
-	rcu_read_lock();
-	for_each_netdev_rcu(&init_net, dev) {
+
+	/* we are running as a workqueue task, so we can sleep */
+	netif_lists_lock(&init_net);
+
+	for_each_netdev(&init_net, dev) {
+		struct in_device *in_dev = in_dev_get(dev);
 		const struct rtnl_link_stats64 *stats;
 		struct rtnl_link_stats64 temp;
-		struct in_device *in_dev = __in_dev_get_rcu(dev);
 
-		if (!in_dev || !in_dev->ifa_list)
+		if (!in_dev || !in_dev->ifa_list ||
+		    ipv4_is_loopback(in_dev->ifa_list->ifa_local)) {
+			in_dev_put(in_dev);
 			continue;
+		}
 
-		if (ipv4_is_loopback(in_dev->ifa_list->ifa_local))
-			continue;
+		in_dev_put(in_dev);
 
 		stats = dev_get_stats(dev, &temp);
 		rx_total += stats->rx_packets;
 		tx_total += stats->tx_packets;
 	}
-	rcu_read_unlock();
+
+	netif_lists_unlock(&init_net);
 
 	retval = 0;