linux-kernel - [PATCH 2/4] irqchip/riscv-imsic: Embed the vector array in lpriv

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Message-ID: <20251015195712.3813004-3-samuel.holland@sifive.com>
Date: Wed, 15 Oct 2025 12:55:13 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Anup Patel <anup@...infault.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc: Palmer Dabbelt <palmer@...belt.com>,
	linux-kernel@...r.kernel.org,
	Alexandre Ghiti <alex@...ti.fr>,
	linux-riscv@...ts.infradead.org,
	Paul Walmsley <pjw@...nel.org>,
	Samuel Holland <samuel.holland@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>
Subject: [PATCH 2/4] irqchip/riscv-imsic: Embed the vector array in lpriv

Reduce pointer chasing and the number of allocations by using a flexible
array member for the vector array instead of a separate allocation.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

 drivers/irqchip/irq-riscv-imsic-state.c | 10 ++--------
 drivers/irqchip/irq-riscv-imsic-state.h |  2 +-
 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
index dc95ad856d80..9a499efdebe3 100644
--- a/drivers/irqchip/irq-riscv-imsic-state.c
+++ b/drivers/irqchip/irq-riscv-imsic-state.c
@@ -487,7 +487,6 @@ static void __init imsic_local_cleanup(void)
 		lpriv = per_cpu_ptr(imsic->lpriv, cpu);
 
 		bitmap_free(lpriv->dirty_bitmap);
-		kfree(lpriv->vectors);
 	}
 
 	free_percpu(imsic->lpriv);
@@ -501,7 +500,8 @@ static int __init imsic_local_init(void)
 	int cpu, i;
 
 	/* Allocate per-CPU private state */
-	imsic->lpriv = alloc_percpu(typeof(*imsic->lpriv));
+	imsic->lpriv = __alloc_percpu(struct_size(imsic->lpriv, vectors, global->nr_ids + 1),
+				      __alignof__(*imsic->lpriv));
 	if (!imsic->lpriv)
 		return -ENOMEM;
 
@@ -521,12 +521,6 @@ static int __init imsic_local_init(void)
 		timer_setup(&lpriv->timer, imsic_local_timer_callback, TIMER_PINNED);
 #endif
 
-		/* Allocate vector array */
-		lpriv->vectors = kcalloc(global->nr_ids + 1, sizeof(*lpriv->vectors),
-					 GFP_KERNEL);
-		if (!lpriv->vectors)
-			goto fail_local_cleanup;
-
 		/* Setup vector array */
 		for (i = 0; i <= global->nr_ids; i++) {
 			vec = &lpriv->vectors[i];
diff --git a/drivers/irqchip/irq-riscv-imsic-state.h b/drivers/irqchip/irq-riscv-imsic-state.h
index 57f951952b0c..196457f1bbca 100644
--- a/drivers/irqchip/irq-riscv-imsic-state.h
+++ b/drivers/irqchip/irq-riscv-imsic-state.h
@@ -40,7 +40,7 @@ struct imsic_local_priv {
 #endif
 
 	/* Local vector table */
-	struct imsic_vector			*vectors;
+	struct imsic_vector			vectors[];
 };
 
 struct imsic_priv {
-- 
2.47.2