From: Ingo Molnar <mingo@kernel.org>
To: Jiri Slaby <jirislaby@kernel.org>
Cc: Uros Bizjak <ubizjak@gmail.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH 1/2] x86/bootflag: Change some static functions to bool
Date: Wed, 26 Feb 2025 13:21:59 +0100 [thread overview]
Message-ID: <Z78HZ5i9aMJq58E4@gmail.com> (raw)
In-Reply-To: <67544c34-2c6f-43d3-b429-c8752f57a7e6@kernel.org>
* Jiri Slaby <jirislaby@kernel.org> wrote:
> On 24. 02. 25, 19:58, Ingo Molnar wrote:
> > So this CodingStyle entry is a red herring, and the !! is absolutely
> > used in the kernel
>
> Sure, for intended conversion to either 0 or 1.
>
> > as an explicit marker of intentional type conversion
> > to bool.
>
> With this in mind, you would have to write "if (!!x)" everywhere.
No, why would I? In a conditional statement any type conversion is for
that evaluation alone and any mistakes are limited to that statement.
On a return statement the value continues to live on in the call
context and has a far longer lifetime. Marking that the type conversion
from int to bool was intentional is prudent, and the use of '!!' is
common practice within the kernel:
starship:~/tip> git grep '!!' -- '*.[ch]' | wc -l
10739
Thanks,
Ingo
prev parent reply other threads:[~2025-02-26 12:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-29 15:47 [PATCH 1/2] x86/bootflag: Change some static functions to bool Uros Bizjak
2025-01-29 15:47 ` [PATCH 2/2] x86/bootflag: Use __builtin_parity() when available Uros Bizjak
2025-01-31 15:15 ` Uros Bizjak
2025-02-22 11:56 ` [tip: x86/boot] x86/boot: Change some static bootflag functions to bool tip-bot2 for Uros Bizjak
2025-02-24 7:18 ` [PATCH 1/2] x86/bootflag: Change some static " Jiri Slaby
2025-02-24 7:24 ` Uros Bizjak
2025-02-24 7:27 ` Jiri Slaby
2025-02-24 7:39 ` Uros Bizjak
2025-02-24 7:48 ` Jiri Slaby
2025-02-24 7:56 ` Uros Bizjak
2025-02-24 18:58 ` Ingo Molnar
2025-02-26 6:31 ` Jiri Slaby
2025-02-26 7:17 ` H. Peter Anvin
2025-02-26 7:21 ` Jiri Slaby
2025-02-26 12:21 ` Ingo Molnar [this message]
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