About pthread_yield() implementation

[Rachid Koucha <rachid.koucha@gmail.com>]

Hi,

Answering a question about pthread_yield() on StackOverflow web site, I
realize that there is a possible implementation bug for this function
(in the GLIBC 2.31 at least):

The source code of the service is:

|/* With the 1-on-1 model we implement this function is equivalent to
the 'sched_yield' function. */ int pthread_yield (void) { return
sched_yield (); } |

||||But this results in a unusual pthread API behavior which *may be an
implementation bug* as it returns directly the result of
/sched_yield()/. Like most of the Linux system calls, the latter returns
-1 and sets *errno* if it fails (even if the manual specifies that it
actually never returns in error). So, theoretically, this makes
/pthread_yield()/ return -1 and set *errno* in case of error although
the pthread API usually returns 0 if successful and the error number in
case of error (*errno* is not supposed to be set). So, the manual is
wrong or at least does not comply with the GLIBC's implementation when
it describes the returned value as:

RETURN VALUE

    On success, pthread_yield() returns 0; on error, it returns an error
    number.


Regards,

Rachid.


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