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

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     2396eefa075a31884d3336e1e94db47a0bd2a456
Gitweb:        https://git.kernel.org/tip/2396eefa075a31884d3336e1e94db47a0bd2a456
Author:        Zijun Hu <quic_zijuhu@quicinc.com>
AuthorDate:    Fri, 18 Oct 2024 20:08:25 +08:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 24 Oct 2024 11:20:06 +02:00

genirq/devres: Don't free interrupt which is not managed by devres

If devres_destroy() does not find a matching devres entry, then
devm_free_irq() emits a warning and tries to free the interrupt.

That's wrong as devm_free_irq() should only undo what devm_request_irq()
set up.

Replace devres_destroy() with a call to devres_release() which only invokes
the release function (free_irq()) in case that a matching devres entry was
found.

[ tglx: Massaged change log ]

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241018-devres_kernel_fix-v2-1-08918ae84982@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 b3e9866..eb16a58 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);