posix: sched: Implement get APIs for scheduling parameters

Initial implementation of `sched_getparam()` and `sched_getscheduler()`
POSIX APIs as a part of PSE53 `_POSIX_PRIORITY_SCHEDULING` option group.
Both functions are actually placeholders and just return `ENOSYS`
since Zephyr does not yet support processes or process scheduling.

Signed-off-by: Dmitrii Golovanov <[email protected]>

Author: golowanow

arch/posix/include/posix_cheats.h

@@ -151,6 +151,8 @@ extern "C" int _posix_zephyr_main(void);
 #define sched_yield(...)		zap_sched_yield(__VA_ARGS__)
 #define sched_get_priority_min(...)	zap_sched_get_priority_min(__VA_ARGS__)
 #define sched_get_priority_max(...)	zap_sched_get_priority_max(__VA_ARGS__)
+#define sched_getparam(...)		zap_sched_getparam(__VA_ARGS__)
+#define sched_getscheduler(...)		zap_sched_getscheduler(__VA_ARGS__)
 
 /* Sleep */
 #define sleep(...)			zap_sleep(__VA_ARGS__)

include/zephyr/posix/sched.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 Intel Corporation
+ * Copyright (c) 2018-2023 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -8,6 +8,8 @@
 
 #include <zephyr/kernel.h>
 
+#include "posix_types.h"
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -46,6 +48,9 @@ static inline int sched_yield(void)
 int sched_get_priority_min(int policy);
 int sched_get_priority_max(int policy);
 
+int sched_getparam(pid_t pid, struct sched_param *param);
+int sched_getscheduler(pid_t pid);
+
 #ifdef __cplusplus
 }
 #endif

lib/posix/sched.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 Intel Corporation
+ * Copyright (c) 2018-2023 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -41,3 +41,32 @@ int sched_get_priority_max(int policy)
 	errno = EINVAL;
 	return -1;
 }
+
+/**
+ * @brief Get scheduling parameters
+ *
+ * See IEEE 1003.1
+ */
+int sched_getparam(pid_t pid, struct sched_param *param)
+{
+	ARG_UNUSED(pid);
+	ARG_UNUSED(param);
+
+	errno = ENOSYS;
+
+	return -1;
+}
+
+/**
+ * @brief Get scheduling policy
+ *
+ * See IEEE 1003.1
+ */
+int sched_getscheduler(pid_t pid)
+{
+	ARG_UNUSED(pid);
+
+	errno = ENOSYS;
+
+	return -1;
+}

tests/posix/common/src/pthread.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018 Intel Corporation
+ * Copyright (c) 2018-2023 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -644,6 +644,23 @@ ZTEST(posix_apis, test_pthread_descriptor_leak)
 	}
 }
 
+ZTEST(posix_apis, test_sched_getparam)
+{
+	struct sched_param param;
+	int rc = sched_getparam(0, &param);
+	int err = errno;
+
+	zassert_true((rc == -1 && err == ENOSYS));
+}
+
+ZTEST(posix_apis, test_sched_getscheduler)
+{
+	int rc = sched_getscheduler(0);
+	int err = errno;
+
+	zassert_true((rc == -1 && err == ENOSYS));
+}
+
 ZTEST(posix_apis, test_sched_policy)
 {
 	/*

tests/posix/headers/src/sched_h.c

@@ -30,8 +30,8 @@ ZTEST(posix_headers, test_sched_h)
 		zassert_not_null(sched_get_priority_max);
 		zassert_not_null(sched_get_priority_min);
 
-		/* zassert_not_null(sched_getparam); */ /* not implemented */
-		/* zassert_not_null(sched_getscheduler); */ /* not implemented */
+		zassert_not_null(sched_getparam);
+		zassert_not_null(sched_getscheduler);
 
 		/* zassert_not_null(sched_rr_get_interval); */ /* not implemented */