Re: [PATCH 4/4] htl: move pthread_self into libc

[Florian Weimer <fw@deneb.enyo.de>]

* Guy-Fleury Iteriteka via Libc-alpha:

> diff --git a/htl/Versions b/htl/Versions
> index 1ef8a6d0..59070181 100644
> --- a/htl/Versions
> +++ b/htl/Versions
> @@ -25,7 +25,9 @@ libc {
>    GLIBC_2.32 {
>      thrd_current; thrd_equal; thrd_sleep; thrd_yield;
>    }
> -
> +  GLIBC_2.36 {
> +    __pthread_self;
> +  }

This needs to be GLIBC_2.37 now.  I think it also needs to be
pthread_self (the public symbol).

> diff --git a/sysdeps/mach/hurd/i386/libc.abilist b/sysdeps/mach/hurd/i386/libc.abilist
> index 26552958..bfa47282 100644
> --- a/sysdeps/mach/hurd/i386/libc.abilist
> +++ b/sysdeps/mach/hurd/i386/libc.abilist
> @@ -29,6 +29,7 @@ GLIBC_2.11 mkostemps64 F
>  GLIBC_2.11 mkstemps F
>  GLIBC_2.11 mkstemps64 F
>  GLIBC_2.12 pthread_equal F
> +GLIBC_2.12 pthread_self F
>  GLIBC_2.13 __fentry__ F
>  GLIBC_2.14 syncfs F
>  GLIBC_2.15 __fdelt_chk F

“GLIBC_2.37 pthread_self” needs to show up there, in addition to the
GLIBC_2.12 version.

What's missing from this change is the construct for setting the
symbol versions, something like:

versioned_symbol (libc, __pthread_self, pthread_self, GLIBC_2_37);
#if OTHER_SHLIB_COMPAT (librt, GLIBC_2_12, GLIBC_2_37)
compat_symbol (libc, __pthread_self, pthread_self, GLIBC_2_12);
#endif

This sets the new symbol version explicitly and provides the old
version as a compatibility symbol.

It may be necessary to introduce a hidden prototype for
__pthread_self, to avoid check-localplt warnings.  You may have to use
libc_hidden_ver and a different name in the C function definition to
work around some symbol management limitations.  Another approach
could use an inline function for pthread_self or __pthread_self, so
that glibc-internal use of the symbol goes away completely.

Use of a __thread variable for ___pthread_self is problematic because
it interferes with dlmopen.  If you use THREAD_GETMEM instead, I
believe you can do away with the conditional check in pthread_self.