Re: [PATCH] libgfortran: Bugfix if not define HAVE_ATOMIC_FETCH_ADD

[Tobias Burnus <tobias@codesourcery.com>]

On 22.12.23 03:36, Lipeng Zhu wrote:
> This patch try to fix the bug when HAVE_ATOMIC_FETCH_ADD is
> not defined in dec_waiting_unlocked function.
>
> libgfortran/ChangeLog:
>
>       * io/io.h (dec_waiting_unlocked): Use
>       __gthread_rwlock_wrlock/__gthread_rwlock_unlock or
>       __gthread_mutex_lock/__gthread_mutex_unlock functions
>       to replace WRLOCK and RWUNLOCK macros.
>
> Signed-off-by: Lipeng Zhu <lipeng.zhu@intel.com>

The change looks good to me + I assume it will work, but have not tested
it myself.

Downside is that it slightly breaks with the abstraction done with all
the macros, but it seems to be the simplest solution.

What is really missing - and should be included in the commit message
(before the ChangeLog block) - is the following information:

    As io.h does not include async.h, the WRLOCK and RWUNLOCK macros are
undefined.

(Or something similar in other words.)

I think that helps others when looking at "git log" and wondering *why*
that change was needed.

Thanks,

Tobias

>   libgfortran/io/io.h | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
> index 15daa0995b1..c7f0f7d7d9e 100644
> --- a/libgfortran/io/io.h
> +++ b/libgfortran/io/io.h
> @@ -1020,9 +1020,15 @@ dec_waiting_unlocked (gfc_unit *u)
>   #ifdef HAVE_ATOMIC_FETCH_ADD
>     (void) __atomic_fetch_add (&u->waiting, -1, __ATOMIC_RELAXED);
>   #else
> -  WRLOCK (&unit_rwlock);
> +#ifdef __GTHREAD_RWLOCK_INIT
> +  __gthread_rwlock_wrlock (&unit_rwlock);
> +  u->waiting--;
> +  __gthread_rwlock_unlock (&unit_rwlock);
> +#else
> +  __gthread_mutex_lock (&unit_rwlock);
>     u->waiting--;
> -  RWUNLOCK (&unit_rwlock);
> +  __gthread_mutex_unlock (&unit_rwlock);
> +#endif
>   #endif
>   }
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