linux-kernel - Re: [PATCH v9 1/8] sched/core: Add __might_sleep

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Message-Id: <20250130.085644.2298700991414831587.fujita.tomonori@gmail.com>
Date: Thu, 30 Jan 2025 08:56:44 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: peterz@...radead.org
Cc: fujita.tomonori@...il.com, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH v9 1/8] sched/core: Add __might_sleep_precision()

On Tue, 28 Jan 2025 12:37:38 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> On Sat, Jan 25, 2025 at 07:18:46PM +0900, FUJITA Tomonori wrote:
>> Add __might_sleep_precision(), Rust friendly version of
>> __might_sleep(), which takes a pointer to a string with the length
>> instead of a null-terminated string.
>> 
>> Rust's core::panic::Location::file(), which gives the file name of a
>> caller, doesn't provide a null-terminated
>> string. __might_sleep_precision() uses a precision specifier in the
>> printk format, which specifies the length of a string; a string
>> doesn't need to be a null-terminated.
>> 
>> Modify __might_sleep() to call __might_sleep_precision() but the
>> impact should be negligible. strlen() isn't called in a normal case;
>> it's called only when printing the error (sleeping function called
>> from invalid context).
>> 
>> Note that Location::file() providing a null-terminated string for
>> better C interoperability is under discussion [1].
> 
> Urgh :/

Yeah... so not acceptable?

Then I switch to the implementation with Rust macros, which gives a
null terminated string.