linux-kernel - [PATCH v4 06/19] irqdomain: Drop revmap mutex

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Message-Id: <20230116135044.14998-7-johan+linaro@kernel.org>
Date:   Mon, 16 Jan 2023 14:50:31 +0100
From:   Johan Hovold <johan+linaro@...nel.org>
To:     Marc Zyngier <maz@...nel.org>, Thomas Gleixner <tglx@...utronix.de>
Cc:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Johan Hovold <johan+linaro@...nel.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Mark-PK Tsai <mark-pk.tsai@...iatek.com>
Subject: [PATCH v4 06/19] irqdomain: Drop revmap mutex

The global irq_domain_mutex is now held in all paths that update the
revmap structures so there is no longer any need for the revmap mutex.

Tested-by: Hsin-Yi Wang <hsinyi@...omium.org>
Tested-by: Mark-PK Tsai <mark-pk.tsai@...iatek.com>
Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
---
 include/linux/irqdomain.h |  2 --
 kernel/irq/irqdomain.c    | 13 ++++++-------
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 5b2718e1c6de..7fd3939328c2 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -143,7 +143,6 @@ struct irq_domain_chip_generic;
  * Revmap data, used internally by the irq domain code:
  * @revmap_size:	Size of the linear map table @revmap[]
  * @revmap_tree:	Radix map tree for hwirqs that don't fit in the linear map
- * @revmap_mutex:	Lock for the revmap
  * @revmap:		Linear table of irq_data pointers
  */
 struct irq_domain {
@@ -171,7 +170,6 @@ struct irq_domain {
 	irq_hw_number_t			hwirq_max;
 	unsigned int			revmap_size;
 	struct radix_tree_root		revmap_tree;
-	struct mutex			revmap_mutex;
 	struct irq_data __rcu		*revmap[];
 };
 
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 23f5919e58b7..248e6acfafbe 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -214,7 +214,6 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, unsigned int s
 
 	/* Fill structure */
 	INIT_RADIX_TREE(&domain->revmap_tree, GFP_KERNEL);
-	mutex_init(&domain->revmap_mutex);
 	domain->ops = ops;
 	domain->host_data = host_data;
 	domain->hwirq_max = hwirq_max;
@@ -501,30 +500,30 @@ static bool irq_domain_is_nomap(struct irq_domain *domain)
 static void irq_domain_clear_mapping(struct irq_domain *domain,
 				     irq_hw_number_t hwirq)
 {
+	lockdep_assert_held(&irq_domain_mutex);
+
 	if (irq_domain_is_nomap(domain))
 		return;
 
-	mutex_lock(&domain->revmap_mutex);
 	if (hwirq < domain->revmap_size)
 		rcu_assign_pointer(domain->revmap[hwirq], NULL);
 	else
 		radix_tree_delete(&domain->revmap_tree, hwirq);
-	mutex_unlock(&domain->revmap_mutex);
 }
 
 static void irq_domain_set_mapping(struct irq_domain *domain,
 				   irq_hw_number_t hwirq,
 				   struct irq_data *irq_data)
 {
+	lockdep_assert_held(&irq_domain_mutex);
+
 	if (irq_domain_is_nomap(domain))
 		return;
 
-	mutex_lock(&domain->revmap_mutex);
 	if (hwirq < domain->revmap_size)
 		rcu_assign_pointer(domain->revmap[hwirq], irq_data);
 	else
 		radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);
-	mutex_unlock(&domain->revmap_mutex);
 }
 
 static void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
@@ -1511,11 +1510,12 @@ static void irq_domain_fix_revmap(struct irq_data *d)
 {
 	void __rcu **slot;
 
+	lockdep_assert_held(&irq_domain_mutex);
+
 	if (irq_domain_is_nomap(d->domain))
 		return;
 
 	/* Fix up the revmap. */
-	mutex_lock(&d->domain->revmap_mutex);
 	if (d->hwirq < d->domain->revmap_size) {
 		/* Not using radix tree */
 		rcu_assign_pointer(d->domain->revmap[d->hwirq], d);
@@ -1524,7 +1524,6 @@ static void irq_domain_fix_revmap(struct irq_data *d)
 		if (slot)
 			radix_tree_replace_slot(&d->domain->revmap_tree, slot, d);
 	}
-	mutex_unlock(&d->domain->revmap_mutex);
 }
 
 /**
-- 
2.38.2