On 10/11/2014 09:04 PM, Tobias Herzke wrote:
> The following example proves that the man page
> pthread_attr_setschedparam.3 is incorrect when it claims that the
> pthread_attr_setschedparam function always succeeds on linux:
>
> #include <pthread.h>
> #include <errno.h>
> int main() {
> pthread_attr_t attr;
> struct sched_param p = {-1}; /* invalid priority */
> if (pthread_attr_init(&attr) == 0)
> if (pthread_attr_setschedpolicy(&attr, SCHED_OTHER) == 0)
> if (pthread_attr_setschedparam(&attr, &p) == EINVAL)
> return 1;
> return 0;
> }
>
> The program exits with exit code 1, therefore pthread_attr_setschedparam
> has returned error code EINVAL.
>
> I could evoke this error on ubuntu 14.04, and verify it by examining the
> eglibc-2.19 source code. The function is implemented in file
> fbtl/pthread_attr_setschedparam.c. For error checking, it calls the
> helper function check_sched_priority_attr which is implemented inline in
> file ./fbtl/pthreadP.h. This function returns EINVAL if a range check fails.
>
> The attached patch corrects the man page. The patch is against the
> current git master, 298f72af973e4bf3975d6a84369286b548e6fb63
Thanks, Tobias.
Patch applied.
Cheers,
Michael
=====
diff --git a/man3/pthread_attr_setschedparam.3 b/man3/pthread_attr_setschedparam.3
index f3db870..8ea4f47 100644
--- a/man3/pthread_attr_setschedparam.3
+++ b/man3/pthread_attr_setschedparam.3
@@ -86,15 +86,22 @@ to
On success, these functions return 0;
on error, they return a nonzero error number.
.SH ERRORS
-POSIX.1 documents
+.BR pthread_attr_setschedparam ()
+can fail with the following error:
+.TP
.B EINVAL
-and
+the priority specified in
+.I param
+does not make sense for the current scheduling policy of
+.IR attr .
+.PP
+POSIX.1 also documents an
.B ENOTSUP
-errors for
+error for
.BR pthread_attr_setschedparam ().
-On Linux these functions always succeed
+This value is never returned on Linux
(but portable and future-proof applications should nevertheless
-handle a possible error return).
+handle this error return value).
.\" .SH VERSIONS
.\" Available since glibc 2.0.
.SH ATTRIBUTES
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
