[glib: 1/2] GThread - Check if sched_setattr is allowed by the system policies before depending on it

[Philip Withnall <pwithnall src gnome org>]

commit 9308ef9a4b82372c5c94e736a2ec68581309a1e3
Author: Sebastian Dröge <sebastian centricular com>
Date:   Mon Feb 10 14:24:48 2020 +0200

    GThread - Check if sched_setattr is allowed by the system policies before depending on it
    
    On Fedora it's apparently not allowed so we'll have to fall back to the
    thread-spawner thread in GThreadPool instead.

 glib/gthread-posix.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)
---
diff --git a/glib/gthread-posix.c b/glib/gthread-posix.c
index 9df6d7994..271bb5dbc 100644
--- a/glib/gthread-posix.c
+++ b/glib/gthread-posix.c
@@ -1211,6 +1211,19 @@ g_system_thread_get_scheduler_settings (GThreadSchedulerSettings *scheduler_sett
     }
   while (res == -1);
 
+  /* Try setting them on the current thread to see if any system policies are
+   * in place that would disallow doing so */
+  res = syscall (SYS_sched_setattr, tid, scheduler_settings->attr, flags);
+  if (res == -1)
+    {
+      int errsv = errno;
+
+      g_debug ("Failed to set thread scheduler attributes: %s", g_strerror (errsv));
+      g_free (scheduler_settings->attr);
+
+      return FALSE;
+    }
+
   return TRUE;
 #else
   return FALSE;