patch 'net/ixgbe: do not create delayed interrupt handler twice' has been queued to stable release 21.11.8

[Kevin Traynor <ktraynor@redhat.com>]

Hi,

FYI, your patch has been queued to stable release 21.11.8

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 08/28/24. So please
shout if anyone has objections.

Also note that after the patch there's a diff of the upstream commit vs the
patch applied to the branch. This will indicate if there was any rebasing
needed to apply to the stable branch. If there were code changes for rebasing
(ie: not only metadata diffs), please double check that the rebase was
correctly done.

Queued patches are on a temporary branch at:
https://github.com/kevintraynor/dpdk-stable

This queued commit can be viewed at:
https://github.com/kevintraynor/dpdk-stable/commit/f6e83fa8b322012c2fe5fa503e697e1fb4de89e8

Thanks.

Kevin

---
From f6e83fa8b322012c2fe5fa503e697e1fb4de89e8 Mon Sep 17 00:00:00 2001
From: Edwin Brossette <edwin.brossette@6wind.com>
Date: Thu, 18 Apr 2024 15:53:07 +0200
Subject: [PATCH] net/ixgbe: do not create delayed interrupt handler twice

[ upstream commit 130ece79670d57760acd18c9671f91a4cd4e07a0 ]

Since link state may need some time to stabilize after a link state
change, we cannot update the link state right after one occurs. So link
state change interrupts (LSC) are handled after a delay. To do this, an
alarm to call a delayed handler is programmed. This delayed handler is
tasked with updating the link after a variable delay of one to four
seconds which should be enough time for the link state to become stable
again.

However, a problem can occur with some models of network cards. For
example, ixgbe_mac_X550EM_x may trigger this interrupt twice because
another interrupt signal is received on the General Purpose Interrupt
pin SPD0, which has the same interrupt handler. In such a case, the
delayed interrupt handler would be programmed to be executed twice.

Since we save the original interrupt mask value to restore it after the
delayed handler is done with its work, we end up overwriting its value
after the second alarm is programmed. Even worse: when restoring it the
first time, the saved original mask variable is reset to 0, so we end up
completely disabling all interrupts when trying to restore this mask
after the second time the delayed handler is executed.

Add a check on the interrupt mask value when programming the alarm for
the delayed handler. If the bit for LSC interrupts is unset, it means an
alarm was already programmed for the delayed handler. In this case, skip
the alarm creation.

Fixes: 9b667210700e ("net/ixgbe: fix blocked interrupts")

Signed-off-by: Edwin Brossette <edwin.brossette@6wind.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 drivers/net/ixgbe/ixgbe_ethdev.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c b/drivers/net/ixgbe/ixgbe_ethdev.c
index 1c65cf77f5..4ba25435fd 100644
--- a/drivers/net/ixgbe/ixgbe_ethdev.c
+++ b/drivers/net/ixgbe/ixgbe_ethdev.c
@@ -4663,12 +4663,18 @@ ixgbe_dev_interrupt_action(struct rte_eth_dev *dev)
 
 		ixgbe_dev_link_status_print(dev);
-		if (rte_eal_alarm_set(timeout * 1000,
-				      ixgbe_dev_interrupt_delayed_handler, (void *)dev) < 0)
-			PMD_DRV_LOG(ERR, "Error setting alarm");
-		else {
-			/* remember original mask */
-			intr->mask_original = intr->mask;
-			/* only disable lsc interrupt */
-			intr->mask &= ~IXGBE_EIMS_LSC;
+
+		/* Don't program delayed handler if LSC interrupt is disabled.
+		 * It means one is already programmed.
+		 */
+		if (intr->mask & IXGBE_EIMS_LSC) {
+			if (rte_eal_alarm_set(timeout * 1000,
+					      ixgbe_dev_interrupt_delayed_handler, (void *)dev) < 0)
+				PMD_DRV_LOG(ERR, "Error setting alarm");
+			else {
+				/* remember original mask */
+				intr->mask_original = intr->mask;
+				/* only disable lsc interrupt */
+				intr->mask &= ~IXGBE_EIMS_LSC;
+			}
 		}
 	}
-- 
2.46.0

---
  Diff of the applied patch vs upstream commit (please double-check if non-empty:
---
--- -	2024-08-23 17:18:11.160806778 +0100
+++ 0041-net-ixgbe-do-not-create-delayed-interrupt-handler-tw.patch	2024-08-23 17:18:09.688429993 +0100
@@ -1 +1 @@
-From 130ece79670d57760acd18c9671f91a4cd4e07a0 Mon Sep 17 00:00:00 2001
+From f6e83fa8b322012c2fe5fa503e697e1fb4de89e8 Mon Sep 17 00:00:00 2001
@@ -5,0 +6,2 @@
+[ upstream commit 130ece79670d57760acd18c9671f91a4cd4e07a0 ]
+
@@ -33 +34,0 @@
-Cc: stable@dpdk.org
@@ -42 +43 @@
-index a6916da0c5..1f93be98ca 100644
+index 1c65cf77f5..4ba25435fd 100644
@@ -45 +46 @@
-@@ -4673,12 +4673,18 @@ ixgbe_dev_interrupt_action(struct rte_eth_dev *dev)
+@@ -4663,12 +4663,18 @@ ixgbe_dev_interrupt_action(struct rte_eth_dev *dev)