commit 4737ad639c7013a156d5db9b88c311dfbff5bb44
author Austin Schuh <austin.linux@gmail.com> Fri Dec 30 14:47:03 2022 -0800
committer Austin Schuh <austin.linux@gmail.com> Tue Jan 03 10:32:23 2023 -0700
tree 550f0bb1c0740402d332b71e2d65afa1e0a9bc53
parent 26c91418eebf9a8203722efc7b4c693196b3be74

Fix FatalUnsetRealtimePriority

Errno was getting modified, so PCHECK wasn't printing the right thing.
Save it and restore it around the scheduler restore.

While I was debugging this with strace, I noticed that we weren't
switching to SCHED_OTHER properly, and that syscall was returning an
error (which was the errorno being displayed with PCHECK).

Change-Id: Iadd0c8725766318f1480ff2f50d51fa0a6a0516d
Signed-off-by: Austin Schuh <austin.linux@gmail.com>

aos/realtime.cc

diff --git a/aos/realtime.cc b/aos/realtime.cc
index ea54d9e..2f299e6 100644
--- a/aos/realtime.cc
+++ b/aos/realtime.cc
@@ -293,10 +293,11 @@
 }
 
 void FatalUnsetRealtimePriority() {
+  int saved_errno = errno;
   // Drop our priority first.  We are about to do lots of work to undo
   // everything, don't get overly clever.
   struct sched_param param;
-  param.sched_priority = 20;
+  param.sched_priority = 0;
   sched_setscheduler(0, SCHED_OTHER, &param);
 
   is_realtime = false;
@@ -311,12 +312,13 @@
       // ignore . and .. which are zeroes for some reason
       if (thread_id != 0) {
         struct sched_param param;
-        param.sched_priority = 20;
+        param.sched_priority = 0;
         sched_setscheduler(thread_id, SCHED_OTHER, &param);
       }
     }
     closedir(dirp);
   }
+  errno = saved_errno;
 }
 
 void RegisterMallocHook() {