linux-kernel - Re: [PATCH v6 02/17] s390: define get

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Message-ID: <YmZtJz4tsP6hr2H5@osiris>
Date:   Mon, 25 Apr 2022 11:43:03 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        tglx@...utronix.de, arnd@...db.de,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>
Subject: Re: [PATCH v6 02/17] s390: define get_cycles macro for arch-override

On Sat, Apr 23, 2022 at 11:26:08PM +0200, Jason A. Donenfeld wrote:
> S390x defines a get_cycles() function, but it forgot to do the usual
> `#define get_cycles get_cycles` dance, making it impossible for generic
> code to see if an arch-specific function was defined.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Heiko Carstens <hca@...ux.ibm.com>
> Cc: Vasily Gorbik <gor@...ux.ibm.com>
> Cc: Alexander Gordeev <agordeev@...ux.ibm.com>
> Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>
> Cc: Sven Schnelle <svens@...ux.ibm.com>
> Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
> ---
>  arch/s390/include/asm/timex.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
> index 2cfce42aa7fc..ce878e85b6e4 100644
> --- a/arch/s390/include/asm/timex.h
> +++ b/arch/s390/include/asm/timex.h
> @@ -197,6 +197,7 @@ static inline cycles_t get_cycles(void)
>  {
>  	return (cycles_t) get_tod_clock() >> 2;
>  }
> +#define get_cycles get_cycles

As far as I can tell this doesn't change anything, since the
asm-generic timex.h header file is not included/used at all on s390
(and if it would, this would have resulted in a compile error).

FWIW, the compiled code also tells me that the s390 specific
get_cycles() version is already used.

Is any of your subsequent patches making sure that the asm generic
header file gets included everywhere? Otherwise I don't see the point
of this patch.