From: Peter Zijlstra <peterz@infradead.org>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Arnd Bergmann <arnd@arndb.de>,
Anna-Maria Behnsen <anna-maria@linutronix.de>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org
Subject: Re: [PATCH V2 04/19] math64: Tidy mul_u64_u32_shr()
Date: Wed, 24 Apr 2024 17:11:33 +0200 [thread overview]
Message-ID: <20240424151133.GR30852@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20240325064023.2997-5-adrian.hunter@intel.com>
On Mon, Mar 25, 2024 at 08:40:08AM +0200, Adrian Hunter wrote:
> Put together declaration and initialization of local variables.
>
> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
Nothing wrong with this patch, but it is highly unlikely this code is
actually tested much. Most (sane) architectures will use the __int128
version.
> include/linux/math64.h | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/include/linux/math64.h b/include/linux/math64.h
> index bf74478926d4..fd13622b2056 100644
> --- a/include/linux/math64.h
> +++ b/include/linux/math64.h
> @@ -179,16 +179,12 @@ static __always_inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
> #ifndef mul_u64_u32_shr
> static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
> {
> - u32 ah, al;
> + u32 ah = a >> 32, al = a;
> u64 ret;
>
> - al = a;
> - ah = a >> 32;
> -
> ret = mul_u32_u32(al, mul) >> shift;
> if (ah)
> ret += mul_u32_u32(ah, mul) << (32 - shift);
> -
> return ret;
> }
> #endif /* mul_u64_u32_shr */
> --
> 2.34.1
>
next prev parent reply other threads:[~2024-04-24 15:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 6:40 [PATCH V2 00/19] timekeeping: Handle potential multiplication overflow Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 01/19] vdso: Consolidate vdso_calc_delta() Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 02/19] vdso: Consolidate nanoseconds calculation Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 03/19] vdso: Add CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 04/19] math64: Tidy mul_u64_u32_shr() Adrian Hunter
2024-04-24 15:11 ` Peter Zijlstra [this message]
2024-03-25 6:40 ` [PATCH V2 05/19] vdso: math64: Provide mul_u64_u32_add_u64_shr() Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 06/19] vdso: Add vdso_data::max_cycles Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 07/19] vdso: Make delta calculation overflow safe Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 08/19] x86/vdso: " Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 09/19] timekeeping: Move timekeeping helper functions Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 10/19] timekeeping: Rename fast_tk_get_delta_ns() to __timekeeping_get_ns() Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 11/19] timekeeping: Tidy timekeeping_cycles_to_ns() slightly Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 12/19] timekeeping: Reuse timekeeping_cycles_to_ns() Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 13/19] timekeeping: Refactor timekeeping helpers Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 14/19] timekeeping: Consolidate " Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 15/19] timekeeping: Fold in timekeeping_delta_to_ns() Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 16/19] timekeeping: Prepare timekeeping_cycles_to_ns() for overflow safety Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 17/19] timekeeping: Make delta calculation overflow safe Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 18/19] timekeeping: Let timekeeping_cycles_to_ns() handle both under and overflow Adrian Hunter
2024-03-25 6:40 ` [PATCH V2 19/19] clocksource: Make watchdog and suspend-timing multiplication overflow safe Adrian Hunter
2024-03-25 18:11 ` [PATCH V2 00/19] timekeeping: Handle potential multiplication overflow Arnd Bergmann
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