Subject: Re: [PATCH][net-next] net/mlx5: Expedite notifier unregistration during device teardown

From: Jakub Kicinski <[email-masked]>
Date: Sat, 14 Mar 2026 10:54:26 -0700

On Thu, 12 Mar 2026 05:48:04 -0400 lirongqing wrote:
> During device hot-unplug, the mlx5 driver expects quickly unregister
> notification chains. The standard atomic_notifier_chain_unregister()
> calls synchronize_rcu(), which introduces significant latency and
> can become a bottleneck during mass resource cleanup.
> 
> Introduce atomic_notifier_chain_unregister_expedited() to leverage
> synchronize_rcu_expedited(), and use it significantly reducing wait
> times in the following paths:
>  - Event Queue (EQ) notifier chain
>  - Firmware event notifier chain
>  - IRQ notifier chain
> 
> This acceleration ensures faster teardown during hot-unplug events.

Some detailed example and how long the whole operation takes would be
great in the commit msg.

>  /**
> + *	atomic_notifier_chain_unregister_expedited - Remove notifier from an atomic notifier chain
> + *	@nh: Pointer to head of the atomic notifier chain
> + *	@n: Entry to remove from notifier chain
> + *
> + *	Removes a notifier from an atomic notifier chain and forcefully
> + *	accelerates the RCU grace period.
> + *
> + *	Returns zero on success or %-ENOENT on failure.

Warning: kernel/notifier.c:211 No description found for return value of 'atomic_notifier_chain_unregister_expedited'

kdoc wants you to use Return: or Returns: the colon is how it knows this
is the doc for return value not just a random mention of the word
Returns
-- 
pw-bot: cr