Re: [PATCH v9 1/8] sched/core: Add __might_sleep_precision()

[Peter Zijlstra]

On Wed, Jan 29, 2025 at 05:14:54PM -0800, Boqun Feng wrote:
> On Thu, Jan 30, 2025 at 08:56:44AM +0900, FUJITA Tomonori wrote:
> > On Tue, 28 Jan 2025 12:37:38 +0100
> > Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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?

Just frustrated we 'need' more ugly to deal with Rust being stupid.

> I would like to see some concrete and technical reasons for why it's not
> acceptable ;-) I'm not sure whether Peter was against this patch or just
> not happy about Location::file() providing a null-terminated string is a
> WIP.

The latter.

I just hate on Rust for being designed by a bunch of C haters, not
wanting to acknowledge the whole frigging world runs on C and they
*have* to deal with interoperability.

That got us a whole pile of ugly including this.