[Bug libc/27417] New: glibc lacks define for sigev_notify_thread_id

[Bug libc/27417] New: glibc lacks define for sigev_notify_thread_id

[alkondratenko at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27417

            Bug ID: 27417
           Summary: glibc lacks define for sigev_notify_thread_id
           Product: glibc
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: alkondratenko at gmail dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

On linux (and freebsd) man page for sigevent lists support for event
notification kind that sends given signal to given thread.

Linux kernel headers define sigev_notify_thread_id in linux/signal.h, but this
header is actually unusable in practice:
https://bugzilla.kernel.org/show_bug.cgi?id=200081

Both freebsd and musl actually have this macro defined under <signal.h>, so
would be reasonable for glibc to also do same.

I guess this might be relevant to "famous" issue of glibc not having gettid
exposed as well. Since in order to use this kind of sigevent someone needs to
use tid. But tid is straightforward to get by using syscall function.

Also notably, glibc does "support" the feature by having sigevent struct with
_sigev_un._tid field, just not via "standard" naming.

Context: gperftools cpu profiler has a feature to use per-thread cpu time
timers for profiling "ticks", since stock interval timers commonly have skewed
tickings. E.g. see: https://github.com/golang/go/issues/14434. And using
per-thread cpu timers obviously depends on this sigevent feature.

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[Bug libc/27417] glibc lacks define for sigev_notify_thread_id

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27417

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |fweimer at redhat dot com
              Flags|                            |security-

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