netdev - [PATCH net] bnxt_en: use irq_update_affinity

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Message-Id: <20241106180811.385175-1-mheib@redhat.com>
Date: Wed,  6 Nov 2024 20:08:11 +0200
From: Mohammad Heib <mheib@...hat.com>
To: netdev@...r.kernel.org,
	michael.chan@...adcom.com
Cc: Mohammad Heib <mheib@...hat.com>
Subject: [PATCH net] bnxt_en: use irq_update_affinity_hint()

irq_set_affinity_hint() is deprecated, Use irq_update_affinity_hint()
instead. This removes the side-effect of actually applying the affinity.

The driver does not really need to worry about spreading its IRQs across
CPUs. The core code already takes care of that. when the driver applies the
affinities by itself, it breaks the users' expectations:

 1. The user configures irqbalance with IRQBALANCE_BANNED_CPULIST in
    order to prevent IRQs from being moved to certain CPUs that run a
    real-time workload.

 2. bnxt_en device reopening will resets the affinity
    in bnxt_open().

 3. bnxt_en has no idea about irqbalance's config, so it may move an IRQ to
    a banned CPU. The real-time workload suffers unacceptable latency.

Signed-off-by: Mohammad Heib <mheib@...hat.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 99d025b69079..cd82f93b20a1 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -10885,7 +10885,7 @@ static void bnxt_free_irq(struct bnxt *bp)
 		irq = &bp->irq_tbl[map_idx];
 		if (irq->requested) {
 			if (irq->have_cpumask) {
-				irq_set_affinity_hint(irq->vector, NULL);
+				irq_update_affinity_hint(irq->vector, NULL);
 				free_cpumask_var(irq->cpu_mask);
 				irq->have_cpumask = 0;
 			}
@@ -10940,10 +10940,10 @@ static int bnxt_request_irq(struct bnxt *bp)
 			irq->have_cpumask = 1;
 			cpumask_set_cpu(cpumask_local_spread(i, numa_node),
 					irq->cpu_mask);
-			rc = irq_set_affinity_hint(irq->vector, irq->cpu_mask);
+			rc = irq_update_affinity_hint(irq->vector, irq->cpu_mask);
 			if (rc) {
 				netdev_warn(bp->dev,
-					    "Set affinity failed, IRQ = %d\n",
+					    "Update affinity hint failed, IRQ = %d\n",
 					    irq->vector);
 				break;
 			}
-- 
2.34.3