linux-kernel - [PATCH v7 02/10] genirq/affinity: Add cpumask to struct irq

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Message-Id: <20250702-isolcpus-io-queues-v7-2-557aa7eacce4@kernel.org>
Date: Wed, 02 Jul 2025 18:33:52 +0200
From: Daniel Wagner <wagi@...nel.org>
To: Jens Axboe <axboe@...nel.dk>, Keith Busch <kbusch@...nel.org>, 
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>, 
 "Michael S. Tsirkin" <mst@...hat.com>
Cc: Aaron Tomlin <atomlin@...mlin.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 Thomas Gleixner <tglx@...utronix.de>, 
 Costa Shulyupin <costa.shul@...hat.com>, Juri Lelli <juri.lelli@...hat.com>, 
 Valentin Schneider <vschneid@...hat.com>, Waiman Long <llong@...hat.com>, 
 Ming Lei <ming.lei@...hat.com>, Frederic Weisbecker <frederic@...nel.org>, 
 Mel Gorman <mgorman@...e.de>, Hannes Reinecke <hare@...e.de>, 
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, 
 linux-kernel@...r.kernel.org, linux-block@...r.kernel.org, 
 linux-nvme@...ts.infradead.org, megaraidlinux.pdl@...adcom.com, 
 linux-scsi@...r.kernel.org, storagedev@...rochip.com, 
 virtualization@...ts.linux.dev, GR-QLogic-Storage-Upstream@...vell.com, 
 Daniel Wagner <wagi@...nel.org>
Subject: [PATCH v7 02/10] genirq/affinity: Add cpumask to struct
 irq_affinity

Pass a cpumask to irq_create_affinity_masks as an additional constraint
to consider when creating the affinity masks. This allows the caller to
exclude specific CPUs, e.g., isolated CPUs (see the 'isolcpus' kernel
command-line parameter).

Signed-off-by: Daniel Wagner <wagi@...nel.org>
---
 include/linux/interrupt.h | 16 ++++++++++------
 kernel/irq/affinity.c     | 12 ++++++++++--
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 51b6484c049345c75816c4a63b4efa813f42f27b..b1a230953514da57e30e601727cd0e94796153d3 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -284,18 +284,22 @@ struct irq_affinity_notify {
  * @nr_sets:		The number of interrupt sets for which affinity
  *			spreading is required
  * @set_size:		Array holding the size of each interrupt set
+ * @mask:		cpumask that constrains which CPUs to consider when
+ *			calculating the number and size of the interrupt sets
  * @calc_sets:		Callback for calculating the number and size
  *			of interrupt sets
  * @priv:		Private data for usage by @calc_sets, usually a
  *			pointer to driver/device specific data.
  */
 struct irq_affinity {
-	unsigned int	pre_vectors;
-	unsigned int	post_vectors;
-	unsigned int	nr_sets;
-	unsigned int	set_size[IRQ_AFFINITY_MAX_SETS];
-	void		(*calc_sets)(struct irq_affinity *, unsigned int nvecs);
-	void		*priv;
+	unsigned int		pre_vectors;
+	unsigned int		post_vectors;
+	unsigned int		nr_sets;
+	unsigned int		set_size[IRQ_AFFINITY_MAX_SETS];
+	const struct cpumask	*mask;
+	void			(*calc_sets)(struct irq_affinity *,
+					     unsigned int nvecs);
+	void			*priv;
 };

 /**
diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index 4013e6ad2b2f1cb91de12bb428b3281105f7d23b..c68156f7847a7920103e39124676d06191304ef6 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -70,7 +70,13 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
 	 */
 	for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
 		unsigned int nr_masks, this_vecs = affd->set_size[i];
-		struct cpumask *result = group_cpus_evenly(this_vecs, &nr_masks);
+		struct cpumask *result;
+
+		if (affd->mask)
+			result = group_mask_cpus_evenly(this_vecs, affd->mask,
+							&nr_masks);
+		else
+			result = group_cpus_evenly(this_vecs, &nr_masks);

 		if (!result) {
 			kfree(masks);
@@ -115,7 +121,9 @@ unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
 	if (resv > minvec)
 		return 0;

-	if (affd->calc_sets) {
+	if (affd->mask) {
+		set_vecs = cpumask_weight(affd->mask);
+	} else if (affd->calc_sets) {
 		set_vecs = maxvec - resv;
 	} else {
 		cpus_read_lock();

-- 
2.50.0