linux-kernel - Re: [PATCH v3] wifi: ath9k: fix printk specifier

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Date:   Fri, 07 Jul 2023 15:44:41 +0200
From:   Toke Høiland-Jørgensen <toke@...e.dk>
To:     Jonas Gorski <jonas.gorski@...il.com>
Cc:     Dongliang Mu <dzm91@...t.edu.cn>, Kalle Valo <kvalo@...nel.org>,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] wifi: ath9k: fix printk specifier

Jonas Gorski <jonas.gorski@...il.com> writes:

> On Thu, 6 Jul 2023 at 13:39, Toke Høiland-Jørgensen <toke@...e.dk> wrote:
>>
>> Dongliang Mu <dzm91@...t.edu.cn> writes:
>>
>> > Smatch reports:
>> >
>> > ath_pci_probe() warn: argument 4 to %lx specifier is cast from pointer
>> > ath_ahb_probe() warn: argument 4 to %lx specifier is cast from pointer
>> >
>> > Fix it by modifying %lx to %p in printk.
>> >
>> > Signed-off-by: Dongliang Mu <dzm91@...t.edu.cn>
>>
>> Third time is the charm! :)
>>
>> Acked-by: Toke Høiland-Jørgensen <toke@...e.dk>
>
> But do we *want* to replace %lx with %p? Because this now causes a
> change in behavior, as the kernel will omit the pointer's address,
> while before it printed the actual memory address. Using %px would
> have kept the original behavior.

So this is basically an informational log message, which really
shouldn't be leaking kernel pointer addresses. So I think %p is the
right choice here, and if someone wants to see the real address for
debugging they should be booting with no_hash_pointers.

> So if the change is desired, it should be noted in the commit message.

That is a fair point, documenting this in the commit message would be
good...

-Toke