linux-kernel - [PATCH v2] genirq/devres: Simplify API devm_free

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Message-Id: <20241018-devres_kernel_fix-v2-1-08918ae84982@quicinc.com>
Date: Fri, 18 Oct 2024 20:08:25 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Zijun Hu <zijun_hu@...oud.com>, linux-kernel@...r.kernel.org, 
 Zijun Hu <quic_zijuhu@...cinc.com>
Subject: [PATCH v2] genirq/devres: Simplify API devm_free_irq()
 implementation

From: Zijun Hu <quic_zijuhu@...cinc.com>

Simplify devm_free_irq() implementation by dedicated API devres_release()
which have below advantages than current devres_destroy() + free_irq().

It is simpler if devm_free_irq() is freeing IRQ which was ever requested
by a devm_request_irq() variant, otherwise, it can avoid the wrong and
unnecessary free_irq() as explained below:

Currently, devm_free_irq() still tries to free the IRQ by free_irq()
even if it can not find a matching devres entry within devres_destroy()
for the IQR under the othewise condition mentioned above.

So that is wrong as devm_free_irq() should only free IRQ requested by
a devm_request_irq() variant.

Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
---
linux-next tree has similar fixes as shown below:
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=0ee4dcafda9576910559f0471a3d6891daf9ab92
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=9bd133f05b1dca5ca4399a76d04d0f6f4d454e44
---
Changes in v2:
- Correct commit message and make it clearer base on Thomas's proposal
- Link to v1: https://lore.kernel.org/r/20241017-devres_kernel_fix-v1-1-4aa0d7c4fee4@quicinc.com
---
 kernel/irq/devres.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/irq/devres.c b/kernel/irq/devres.c
index b3e98668f4dd..eb16a58e0322 100644
--- a/kernel/irq/devres.c
+++ b/kernel/irq/devres.c
@@ -141,9 +141,8 @@ void devm_free_irq(struct device *dev, unsigned int irq, void *dev_id)
 {
 	struct irq_devres match_data = { irq, dev_id };
 
-	WARN_ON(devres_destroy(dev, devm_irq_release, devm_irq_match,
+	WARN_ON(devres_release(dev, devm_irq_release, devm_irq_match,
 			       &match_data));
-	free_irq(irq, dev_id);
 }
 EXPORT_SYMBOL(devm_free_irq);
 

---
base-commit: 9bd133f05b1dca5ca4399a76d04d0f6f4d454e44
change-id: 20241017-devres_kernel_fix-4b29be51bded

Best regards,
-- 
Zijun Hu <quic_zijuhu@...cinc.com>