linux-kernel - Re: [RFC 2/2] wl3501_cs: reduce stack size for KASAN

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Date:   Tue, 25 Jul 2017 16:50:47 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     "the arch/x86 maintainers" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>
Subject: Re: [RFC 2/2] wl3501_cs: reduce stack size for KASAN

On Tue, Jul 25, 2017 at 2:52 PM, Kalle Valo <kvalo@...eaurora.org> wrote:
> Arnd Bergmann <arnd@...db.de> writes:
>
>> Inlining functions with local variables can lead to excessive stack usage
>> with KASAN after a previous patch that modifies the outsb/insb helpers
>> on x86.
>>
>> drivers/net/wireless/wl3501_cs.c: In function 'wl3501_rx_interrupt':
>> drivers/net/wireless/wl3501_cs.c:1103:1: error: the frame size of 2232 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]
>>
>> Marking the two callers of insb/outb 'noinline' prevents the compiler
>> from adding up the stack usage for each of the local variables passed
>> into those, reducing the maximum stack frame size to 800 bytes with
>> KASAN again.
>>
>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>
> Arnd, based on the discussion I'm dropping. Please let me know if I
> should take this still.

Thanks, that's good. The problem has become unreproducible and
I assume it's gone for good with the new x86 fix. In the unlikely
case some form of the problem comes back in another randconfig,
I'll post a new patch.

       Arnd