[PATCH] Fix num_processors_ignoring_omp.

[Nikita Ermakov]

From: Nikita Ermakov <address@hidden>

- Update comments to correspond closed glibc bug #21542.

- In case of failed _SC_NPROCESSORS_CONF use the maximum between
  nprocs_current and nprocs to meet the requirements of
  num_processors (NPROC_ALL) >= num_processors (NPROC_CURRENT).
---
 lib/nproc.c | 22 +++++++---------------
 1 file changed, 7 insertions(+), 15 deletions(-)

diff --git a/lib/nproc.c b/lib/nproc.c
index 77b876027..a550711b4 100644
--- a/lib/nproc.c
+++ b/lib/nproc.c
@@ -217,17 +217,14 @@ num_processors_ignoring_omp (enum nproc_query query)
      the /sys and /proc file systems (see
      glibc/sysdeps/unix/sysv/linux/getsysstats.c).
      In some situations these file systems are not mounted, and the sysconf
-     call returns 1, which does not reflect the reality.  */
+     call returns 1 or 2, which does not reflect the reality.  */
+  unsigned long nprocs_current = num_processors_via_affinity_mask ();
 
   if (query == NPROC_CURRENT)
     {
       /* Try the modern affinity mask system call.  */
-      {
-        unsigned long nprocs = num_processors_via_affinity_mask ();
-
-        if (nprocs > 0)
-          return nprocs;
-      }
+      if (nprocs_current > 0)
+        return nprocs_current;
 
 #if defined _SC_NPROCESSORS_ONLN
       { /* This works on glibc, Mac OS X 10.5, FreeBSD, AIX, OSF/1, Solaris,
@@ -249,15 +246,10 @@ num_processors_ignoring_omp (enum nproc_query query)
         /* On Linux systems with glibc, this information comes from the /sys 
and
            /proc file systems (see 
glibc/sysdeps/unix/sysv/linux/getsysstats.c).
            In some situations these file systems are not mounted, and the
-           sysconf call returns 1.  But we wish to guarantee that
+           sysconf call returns 1 or 2.  But we wish to guarantee that
            num_processors (NPROC_ALL) >= num_processors (NPROC_CURRENT).  */
-        if (nprocs == 1)
-          {
-            unsigned long nprocs_current = num_processors_via_affinity_mask ();
-
-            if (nprocs_current > 0)
-              nprocs = nprocs_current;
-          }
+        if (nprocs_current > nprocs)
+          nprocs = nprocs_current;
 # endif
 
         if (nprocs > 0)
-- 
2.19.2