Re: [PATCH v10 1/8] sched/core: Add __might_sleep_precision()

[Alice Ryhl <aliceryhl@google.com>]

On Sat, Feb 8, 2025 at 4:01 AM FUJITA Tomonori
<fujita.tomonori@gmail.com> wrote:
>
> On Fri, 7 Feb 2025 18:12:58 +0000
> David Laight <david.laight.linux@gmail.com> wrote:
>
> >>  static void print_preempt_disable_ip(int preempt_offset, unsigned long ip)
> >>  {
> >>      if (!IS_ENABLED(CONFIG_DEBUG_PREEMPT))
> >> @@ -8717,7 +8699,8 @@ static inline bool resched_offsets_ok(unsigned int offsets)
> >>      return nested == offsets;
> >>  }
> >>
> >> -void __might_resched(const char *file, int line, unsigned int offsets)
> >> +static void __might_resched_precision(const char *file, int len, int line,
> >
> > For clarity that ought to be file_len.
>
> Yeah, I'll update.
>
> >> +                                  unsigned int offsets)
> >>  {
> >>      /* Ratelimiting timestamp: */
> >>      static unsigned long prev_jiffy;
> >> @@ -8740,8 +8723,10 @@ void __might_resched(const char *file, int line, unsigned int offsets)
> >>      /* Save this before calling printk(), since that will clobber it: */
> >>      preempt_disable_ip = get_preempt_disable_ip(current);
> >>
> >> -    pr_err("BUG: sleeping function called from invalid context at %s:%d\n",
> >> -           file, line);
> >> +    if (len < 0)
> >> +            len = strlen(file);
> >
> > No need for strlen(), just use a big number instead of -1.
> > Anything bigger than a sane upper limit on the filename length will do.
>
> Ah, that's right. Just passing the maximum precision (1<<15-1) works.
>
> The precision specifies the maximum length. vsnprintf() always
> iterates through a string until it reaches the maximum length or
> encounters the null terminator. So strlen() here is useless.
>
> Alice and Boqun, the above change is fine? Can I keep the tags?

I'd probably like a comment explaining the meaning of this constant
somewhere, but sure ok with me.

Alice