From cc25486b233ada380ac8452f47f5fb35536888f4 Mon Sep 17 00:00:00 2001
From: q66 <q66@chimera-linux.org>
Date: Sat, 23 Mar 2024 20:51:52 +0100
Subject: [PATCH] Use CPU_COUNT to get the number of set CPUs

This fixes an issue with the number getting very big due to
CPU_ISSET not returning exactly 0 or 1.

This also fixes scenarios where there are holes in the CPU
set. E.g. for a simple run like `taskset --cpu-list 1,2,4 ...`
the old code would return 2 instead of 3, due to iterating
until `ncores` (which is 3) and therefore not accounting for
CPUs further in the set.

Ref https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3784
---
 glib/gthread.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/glib/gthread.c b/glib/gthread.c
index b39acc475..a264353ec 100644
--- a/glib/gthread.c
+++ b/glib/gthread.c
@@ -1092,7 +1092,6 @@ g_get_num_processors (void)
     return count;
 #elif defined(_SC_NPROCESSORS_ONLN) && defined(THREADS_POSIX) && defined(HAVE_PTHREAD_GETAFFINITY_NP)
   {
-    int idx;
     int ncores = MIN (sysconf (_SC_NPROCESSORS_ONLN), CPU_SETSIZE);
     cpu_set_t cpu_mask;
     CPU_ZERO (&cpu_mask);
@@ -1100,8 +1099,7 @@ g_get_num_processors (void)
     int af_count = 0;
     int err = pthread_getaffinity_np (pthread_self (), sizeof (cpu_mask), &cpu_mask);
     if (!err)
-      for (idx = 0; idx < ncores && idx < CPU_SETSIZE; ++idx)
-        af_count += CPU_ISSET (idx, &cpu_mask);
+      af_count = CPU_COUNT (&cpu_mask);
 
     int count = (af_count > 0) ? af_count : ncores;
     return count;