linux-kernel - Re: [PATCH] staging: r8188eu: fix NULL check for rcu pointer

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Message-ID: <20230131172336.smmc7dfvk54zftw6@viti.kaiser.cx>
Date:   Tue, 31 Jan 2023 18:23:36 +0100
From:   Martin Kaiser <martin@...ser.cx>
To:     Dan Carpenter <error27@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Michael Straube <straube.linux@...il.com>,
        Pavel Skripkin <paskripkin@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: r8188eu: fix NULL check for rcu pointer

Hello Dan and all,

Thus wrote Dan Carpenter (error27@...il.com):

> This patch is fine but it's a clean up and not a fix.  The original code
> doesn't dereference "br_port".  I guess the new code is faster and
> especially if you have lockdep enabled, so maybe in that sense it is a
> fix.

ok, I see. The br_port pointer may no longer be valid after rcu_unlock
but we can still check it for NULL at that time without dereferencing it.

Thanks for the clarification,
Martin