Adding execution context get/put to posix env

Signed-off-by: Adam Rutkowski <adam.j.rutkowski@intel.com>

env/posix/ocf_env.c

@@ -130,8 +130,64 @@ void env_stack_trace(void)
 }
 
 /* *** CRC *** */
-
 uint32_t env_crc32(uint32_t crc, uint8_t const *data, size_t len)
 {
 	return crc32(crc, data, len);
 }
+
+/* *** execution contexts *** */
+pthread_mutex_t *exec_context_mutex;
+
+static void __attribute__((constructor)) init_execution_context(void)
+{
+	unsigned count = env_get_execution_context_count();
+	unsigned i;
+
+	ENV_BUG_ON(count == 0);
+	exec_context_mutex = malloc(count * sizeof(exec_context_mutex[0]));
+	ENV_BUG_ON(exec_context_mutex == NULL);
+	for (i = 0; i < count; i++)
+		ENV_BUG_ON(pthread_mutex_init(&exec_context_mutex[i], NULL));
+}
+
+static void __attribute__((destructor)) deinit_execution_context(void)
+{
+	unsigned count = env_get_execution_context_count();
+	unsigned i;
+
+	ENV_BUG_ON(count == 0);
+	ENV_BUG_ON(exec_context_mutex == NULL);
+
+	for (i = 0; i < count; i++)
+		ENV_BUG_ON(pthread_mutex_destroy(&exec_context_mutex[i]));
+	free(exec_context_mutex);
+}
+
+/* get_execuction_context must assure that after the call finishes, the caller
+ * will not get preempted from current execution context. For userspace env
+ * we simulate this behavior by acquiring per execution context mutex. As a
+ * result the caller might actually get preempted, but no other thread will
+ * execute in this context by the time the caller puts current execution ctx. */
+unsigned env_get_execution_context(void)
+{
+	unsigned cpu;
+
+	cpu = sched_getcpu();
+	cpu = (cpu == -1) ?  0 : cpu;
+
+	ENV_BUG_ON(pthread_mutex_lock(&exec_context_mutex[cpu]));
+
+	return cpu;
+}
+
+void env_put_execution_context(unsigned ctx)
+{
+	pthread_mutex_unlock(&exec_context_mutex[ctx]);
+}
+
+unsigned env_get_execution_context_count(void)
+{
+	int num = sysconf(_SC_NPROCESSORS_ONLN);
+
+	return (num == -1) ? 0 : num;
+}

env/posix/ocf_env.h

@@ -644,4 +644,9 @@ uint32_t env_crc32(uint32_t crc, uint8_t const *data, size_t len);
 
 #define ENV_PRIu64 "lu"
 
+unsigned env_get_execution_context(void);
+void env_put_execution_context(unsigned ctx);
+unsigned env_get_execution_context_count(void);
+
+
 #endif /* __OCF_ENV_H__ */