netdev - Re: [PATCH net 2/2] netpoll: Use rcu_access_pointer() in netpoll_poll

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Message-ID: <ZzsxDhFqALWCojNb@localhost.localdomain>
Date: Mon, 18 Nov 2024 13:20:30 +0100
From: Michal Kubiak <michal.kubiak@...el.com>
To: Breno Leitao <leitao@...ian.org>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>, Herbert Xu
	<herbert@...dor.apana.org.au>, Stephen Hemminger
	<stephen@...workplumber.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <paulmck@...nel.org>
Subject: Re: [PATCH net 2/2] netpoll: Use rcu_access_pointer() in
 netpoll_poll_lock

On Mon, Nov 18, 2024 at 03:15:18AM -0800, Breno Leitao wrote:
> The ndev->npinfo pointer in netpoll_poll_lock() is RCU-protected but is
> being accessed directly for a NULL check. While no RCU read lock is held
> in this context, we should still use proper RCU primitives for
> consistency and correctness.
> 
> Replace the direct NULL check with rcu_access_pointer(), which is the
> appropriate primitive when only checking for NULL without dereferencing
> the pointer. This function provides the necessary ordering guarantees
> without requiring RCU read-side protection.
> 
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> Fixes: bea3348eef27 ("[NET]: Make NAPI polling independent of struct net_device objects.")

nitpick: As for the first patch - please check the tags order.

Thanks,
Reviewed-by: Michal Kubiak <michal.kubiak@...el.com>