From: Jan Engelhardt <jengelh@inai.de>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Bill Wendling' <morbo@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Bill Wendling <isanbard@gmail.com>,
Tony Luck <tony.luck@intel.com>, Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Phillip Potter <phil@philpotter.co.uk>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Jan Kara <jack@suse.com>,
Pablo Neira Ayuso <pablo@netfilter.org>,
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Florian Westphal <fw@strlen.de>,
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<netfilter-devel@vger.kernel.org>,
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clang-built-linux <llvm@lists.linux.dev>
Subject: RE: [PATCH 00/12] Clang -Wformat warning fixes
Date: Fri, 10 Jun 2022 11:22:46 +0200 (CEST) [thread overview]
Message-ID: <so239116-75sq-89rs-nron-35nsq660rs8n@vanv.qr> (raw)
In-Reply-To: <724889aa6a8d4d41b8557733610c7657@AcuMS.aculab.com>
On Friday 2022-06-10 11:14, David Laight wrote:
>> >Yep, IMHO definitely should be fixed.
>> >It is even possible that using "%s" is faster because the printf
>> >code doesn't have to scan the string for format effectors.
>>
>> I see no special handling; the vsnprintf function just loops
>> over fmt as usual and I see no special casing of fmt by
>> e.g. strcmp(fmt, "%s") == 0 to take a shortcut.
>
>Consider the difference between:
> printf("fubar");
>and
> printf("%s", "fubar");
>In the former all of "fubar" is checked for '%'.
>In the latter only the length of "fubar" has to be counted.
To check the length of "fubar", printf first needs to know that there
even is an argument to be pulled from the stack, which it does by
evaluating the format string.
So, in fairness, it's more like:
>> In the latter, all of "%s" is checked for '%'.
next prev parent reply other threads:[~2022-06-10 9:22 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-09 22:16 Bill Wendling
2022-06-09 22:16 ` [PATCH 01/12] x86/mce: use correct format characters Bill Wendling
2022-06-09 23:14 ` Randy Dunlap
2022-06-09 23:18 ` Bill Wendling
2022-06-09 22:16 ` [PATCH 02/12] x86/CPU/AMD: " Bill Wendling
2022-06-09 22:16 ` [PATCH 03/12] x86/e820: " Bill Wendling
2022-06-09 22:16 ` [PATCH 04/12] blk-cgroup: " Bill Wendling
2022-06-10 8:10 ` Christoph Hellwig
2022-06-09 22:16 ` [PATCH 05/12] fs: quota: " Bill Wendling
2022-06-09 22:16 ` [PATCH 06/12] PNP: " Bill Wendling
2022-06-09 22:16 ` [PATCH 07/12] driver/char: " Bill Wendling
2022-06-10 5:18 ` Greg Kroah-Hartman
2022-06-13 18:40 ` Bill Wendling
2022-06-09 22:16 ` [PATCH 08/12] cdrom: " Bill Wendling
2022-06-12 16:23 ` Phillip Potter
2022-06-13 18:47 ` Bill Wendling
2022-06-09 22:16 ` [PATCH 09/12] ALSA: seq: " Bill Wendling
2022-06-09 22:16 ` [PATCH 10/12] " Bill Wendling
2022-06-09 22:16 ` [PATCH 11/12] ALSA: control: " Bill Wendling
2022-06-09 22:16 ` [PATCH 12/12] netfilter: conntrack: " Bill Wendling
2022-07-11 14:35 ` Pablo Neira Ayuso
2022-06-09 22:25 ` [PATCH 00/12] Clang -Wformat warning fixes Andrew Morton
2022-06-09 22:49 ` Bill Wendling
2022-06-09 23:03 ` Jan Engelhardt
2022-06-09 23:16 ` Bill Wendling
2022-06-10 1:19 ` Andrew Morton
2022-06-10 5:20 ` Greg Kroah-Hartman
2022-06-10 12:44 ` Joe Perches
2022-06-10 8:17 ` David Laight
2022-06-10 8:32 ` Jan Engelhardt
2022-06-10 9:14 ` David Laight
2022-06-10 9:22 ` Jan Engelhardt [this message]
2022-06-10 0:32 ` Nick Desaulniers
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