[net PATCH v2] hsr: Simplify code for announcing HSR nodes timer setup

[net PATCH v2] hsr: Simplify code for announcing HSR nodes timer setup

[Lukasz Majewski]

Up till now the code to start HSR announce timer, which triggers sending
supervisory frames, was assuming that hsr_netdev_notify() would be called
at least twice for hsrX interface. This was required to have different
values for old and current values of network device's operstate.

This is problematic for a case where hsrX interface is already in the
operational state when hsr_netdev_notify() is called, so timer is not
configured to trigger and as a result the hsrX is not sending supervisory
frames to HSR ring.

This error has been discovered when hsr_ping.sh script was run. To be
more specific - for the hsr1 and hsr2 the hsr_netdev_notify() was
called at least twice with different IF_OPER_{LOWERDOWN|DOWN|UP} states
assigned in hsr_check_carrier_and_operstate(hsr). As a result there was
no issue with sending supervisory frames.
However, with hsr3, the notify function was called only once with
operstate set to IF_OPER_UP and timer responsible for triggering
supervisory frames was not fired.

The solution is to use netif_oper_up() and netif_running() helper
functions to assess if network hsrX device is up.
Only then, when the timer is not already pending, it is started.
Otherwise it is deactivated.

Signed-off-by: Lukasz Majewski <lukma@denx.de>

Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
---
Changes for v2:

- Add extra condition to check if the hsr network device is running
  (not only up).

- Only start announce timer when it is not pending (to avoid period
  shortening/violation)
---
 net/hsr/hsr_device.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index e9d45133d641..5afc450d0855 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -61,39 +61,36 @@ static bool hsr_check_carrier(struct hsr_port *master)
 	return false;
 }
 
-static void hsr_check_announce(struct net_device *hsr_dev,
-			       unsigned char old_operstate)
+static void hsr_check_announce(struct net_device *hsr_dev)
 {
 	struct hsr_priv *hsr;
 
 	hsr = netdev_priv(hsr_dev);
-
-	if (READ_ONCE(hsr_dev->operstate) == IF_OPER_UP && old_operstate != IF_OPER_UP) {
-		/* Went up */
-		hsr->announce_count = 0;
-		mod_timer(&hsr->announce_timer,
-			  jiffies + msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL));
+	if (netif_running(hsr_dev) && netif_oper_up(hsr_dev)) {
+		/* Enable announce timer and start sending supervisory frames */
+		if (!timer_pending(&hsr->announce_timer)) {
+			hsr->announce_count = 0;
+			mod_timer(&hsr->announce_timer, jiffies +
+				  msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL));
+		}
+	} else {
+		/* Deactivate the announce timer  */
+		timer_delete(&hsr->announce_timer);
 	}
-
-	if (READ_ONCE(hsr_dev->operstate) != IF_OPER_UP && old_operstate == IF_OPER_UP)
-		/* Went down */
-		del_timer(&hsr->announce_timer);
 }
 
 void hsr_check_carrier_and_operstate(struct hsr_priv *hsr)
 {
 	struct hsr_port *master;
-	unsigned char old_operstate;
 	bool has_carrier;
 
 	master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
 	/* netif_stacked_transfer_operstate() cannot be used here since
 	 * it doesn't set IF_OPER_LOWERLAYERDOWN (?)
 	 */
-	old_operstate = READ_ONCE(master->dev->operstate);
 	has_carrier = hsr_check_carrier(master);
 	hsr_set_operstate(master, has_carrier);
-	hsr_check_announce(master->dev, old_operstate);
+	hsr_check_announce(master->dev);
 }
 
 int hsr_get_max_mtu(struct hsr_priv *hsr)
-- 
2.20.1

Re: [net PATCH v2] hsr: Simplify code for announcing HSR nodes timer setup

[Simon Horman]

On Tue, May 07, 2024 at 01:12:14PM +0200, Lukasz Majewski wrote:
> Up till now the code to start HSR announce timer, which triggers sending
> supervisory frames, was assuming that hsr_netdev_notify() would be called
> at least twice for hsrX interface. This was required to have different
> values for old and current values of network device's operstate.
> 
> This is problematic for a case where hsrX interface is already in the
> operational state when hsr_netdev_notify() is called, so timer is not
> configured to trigger and as a result the hsrX is not sending supervisory
> frames to HSR ring.
> 
> This error has been discovered when hsr_ping.sh script was run. To be
> more specific - for the hsr1 and hsr2 the hsr_netdev_notify() was
> called at least twice with different IF_OPER_{LOWERDOWN|DOWN|UP} states
> assigned in hsr_check_carrier_and_operstate(hsr). As a result there was
> no issue with sending supervisory frames.
> However, with hsr3, the notify function was called only once with
> operstate set to IF_OPER_UP and timer responsible for triggering
> supervisory frames was not fired.
> 
> The solution is to use netif_oper_up() and netif_running() helper
> functions to assess if network hsrX device is up.
> Only then, when the timer is not already pending, it is started.
> Otherwise it is deactivated.
> 
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> 
> Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
> ---
> Changes for v2:
> 
> - Add extra condition to check if the hsr network device is running
>   (not only up).
> 
> - Only start announce timer when it is not pending (to avoid period
>   shortening/violation)

Reviewed-by: Simon Horman <horms@kernel.org>

Re: [net PATCH v2] hsr: Simplify code for announcing HSR nodes timer setup

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue,  7 May 2024 13:12:14 +0200 you wrote:
> Up till now the code to start HSR announce timer, which triggers sending
> supervisory frames, was assuming that hsr_netdev_notify() would be called
> at least twice for hsrX interface. This was required to have different
> values for old and current values of network device's operstate.
> 
> This is problematic for a case where hsrX interface is already in the
> operational state when hsr_netdev_notify() is called, so timer is not
> configured to trigger and as a result the hsrX is not sending supervisory
> frames to HSR ring.
> 
> [...]

Here is the summary with links:
  - [net,v2] hsr: Simplify code for announcing HSR nodes timer setup
    https://git.kernel.org/netdev/net/c/4893b8b3ef8d

You are awesome, thank you!
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