Re: [PATCH v6 6/7] reboot: use devm_blocking_notifier_chain_register()

[Bradley Morgan <bradley.morgan@linux.dev>]

On 13 November 2026 10:44:54 GMT, Eliav Farber <farbere@amazon.com> wrote:
>Replace the manual devres_alloc() + register_reboot_notifier() pattern
>with a single call to devm_blocking_notifier_chain_register(), removing
>the devm_unregister_reboot_notifier() callback.
>
>The removed callback wrapped unregister_reboot_notifier() in WARN_ON().
>The generic helper ignores the unregister return value, so that warning
>is gone. It could only fire if a caller had already unregistered the
>notifier itself, which no in-tree user does.

Good. Cleanup well needed 

Reviewed-by: Bradley Morgan <bradley.morgan@linux.dev>


>
>Signed-off-by: Eliav Farber <farbere@amazon.com>
>---
>Changes in v6:
>- Rebased onto v7.4-rc1.
>- Commit message: record that the removed callback's WARN_ON() on a
>  failed unregister goes away, because
>  devm_blocking_notifier_chain_register() ignores the unregister return
>  value. No change to the code.
>
>Changes in v3:
>- Fix commit message to accurately describe the old code as using
>  devres_alloc() + register_reboot_notifier() (Sashiko)
>
> kernel/reboot.c | 24 ++----------------------
> 1 file changed, 2 insertions(+), 22 deletions(-)
>
>diff --git a/kernel/reboot.c b/kernel/reboot.c
>index 9a84401adde5..2fb8700c726d 100644
>--- a/kernel/reboot.c
>+++ b/kernel/reboot.c
>@@ -146,30 +146,10 @@ int unregister_reboot_notifier(struct notifier_block *nb)
> }
> EXPORT_SYMBOL(unregister_reboot_notifier);
> 
>-static void devm_unregister_reboot_notifier(struct device *dev, void *res)
>-{
>-	WARN_ON(unregister_reboot_notifier(*(struct notifier_block **)res));
>-}
>-
> int devm_register_reboot_notifier(struct device *dev, struct
> notifier_block *nb)
> {
>-	struct notifier_block **rcnb;
>-	int ret;
>-
>-	rcnb = devres_alloc(devm_unregister_reboot_notifier,
>-			    sizeof(*rcnb), GFP_KERNEL);
>-	if (!rcnb)
>-		return -ENOMEM;
>-
>-	ret = register_reboot_notifier(nb);
>-	if (!ret) {
>-		*rcnb = nb;
>-		devres_add(dev, rcnb);
>-	} else {
>-		devres_free(rcnb);
>-	}
>-
>-	return ret;
>+	return devm_blocking_notifier_chain_register(dev,
>+						     &reboot_notifier_list, nb);
> }
> EXPORT_SYMBOL(devm_register_reboot_notifier);
> 
>

--- Thanks!