Timur Davydov has uploaded this change for review.

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vty: make CPU scheduling optional based on platform support

Add configure checks for sched_* APIs and guard their usage
in cpu_sched_vty with HAVE_SCHED_* macros.

If scheduler functions are not available, return -ENOTSUP
instead of failing at build time.

Also change osmo_cpu_sched_vty_init() to return int.

This improves portability on platforms lacking full sched
support (e.g. non-Linux or restricted environments).

Change-Id: Ic5b7e39fac16531d370cb81f769ba87fef18cb81
---
M configure.ac
M include/osmocom/vty/cpu_sched_vty.h
M src/vty/cpu_sched_vty.c
3 files changed, 15 insertions(+), 2 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/53/42653/1

diff --git a/configure.ac b/configure.ac
index b5f858f..cde4446 100644
--- a/configure.ac
+++ b/configure.ac
@@ -162,6 +162,10 @@
 AC_CHECK_HEADERS([sched.h sys/mount.h sys/param.h])
 AC_CHECK_FUNCS([setns unshare mount])
 
+dnl Check the scheduller functions
+AC_CHECK_HEADERS([sched.h])
+AC_CHECK_FUNCS([sched_setaffinity sched_setscheduler sched_getaffinity])
+
 dnl Check whether CLONE_NEWNET is available
 AC_CHECK_DECL([CLONE_NEWNET],
   [AC_DEFINE([HAVE_CLONE_NEWNET], [1],
diff --git a/include/osmocom/vty/cpu_sched_vty.h b/include/osmocom/vty/cpu_sched_vty.h
index 171f168..b04ee34 100644
--- a/include/osmocom/vty/cpu_sched_vty.h
+++ b/include/osmocom/vty/cpu_sched_vty.h
@@ -31,7 +31,7 @@
  * \file cpu_sched_vty.h
  */
 
-void osmo_cpu_sched_vty_init(void *tall_ctx);
+int osmo_cpu_sched_vty_init(void *tall_ctx);
 int osmo_cpu_sched_vty_apply_localthread(void);
 
 /*! @} */
diff --git a/src/vty/cpu_sched_vty.c b/src/vty/cpu_sched_vty.c
index 4f3eeb1..a712860 100644
--- a/src/vty/cpu_sched_vty.c
+++ b/src/vty/cpu_sched_vty.c
@@ -331,6 +331,7 @@
 static int my_sched_setaffinity(enum sched_vty_thread_id tid_type, pid_t pid,
 				cpu_set_t *cpuset, size_t cpuset_size)
 {
+#ifdef HAVE_SCHED_SETAFFINITY
 	DIR *proc_dir;
 	struct dirent *entry;
 	char dirname[100];
@@ -369,7 +370,9 @@
 
 	closedir(proc_dir);
 	return rc;
-
+#else /* HAVE_SCHED_SETAFFINITY */
+	return -ENOTSUP;
+#endif /* HAVE_SCHED_SETAFFINITY */
 }
 
 DEFUN_ATTR(cfg_sched_cpu_affinity, cfg_sched_cpu_affinity_cmd,
@@ -464,6 +467,7 @@
 
 static int set_sched_rr(unsigned int prio)
 {
+#ifdef HAVE_SCHED_SETSCHEDULER
 	struct sched_param param;
 	int rc;
 	memset(&param, 0, sizeof(param));
@@ -476,6 +480,9 @@
 		return -1;
 	}
 	return 0;
+#else /* HAVE_SCHED_SETSCHEDULER */
+	return -ENOTSUP;
+#endif /* HAVE_SCHED_SETSCHEDULER */
 }
 
 DEFUN_ATTR(cfg_sched_policy, cfg_sched_policy_cmd,
@@ -558,10 +565,12 @@
 		cpuset = CPU_ALLOC(get_num_cpus());
 		cpuset_size = CPU_ALLOC_SIZE(get_num_cpus());
 		CPU_ZERO_S(cpuset_size, cpuset);
+#ifdef HAVE_SCHED_GETAFFINITY
 		if (sched_getaffinity(tid_it, cpuset_size, cpuset) == 0) {
 			if (generate_cpu_hex_mask(str_mask, sizeof(str_mask), cpuset, cpuset_size) < 0)
 				str_mask[0] = '\0';
 		}
+#endif /* HAVE_SCHED_GETAFFINITY */
 		CPU_FREE(cpuset);
 
 		vty_out(vty, " TID: %lu, NAME: '%s', cpu-affinity: %s%s",

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