From d13e3a4432b8656c7c3cbb8da883885baa591bcd Mon Sep 17 00:00:00 2001
From: Stefan Lankes <slankes@eonerc.rwth-aachen.de>
Date: Mon, 9 Nov 2015 23:54:03 +0100
Subject: [PATCH] add helper function to determine the next free core

- we start with the second core, because the first is used by the LwIP thread
---
 hermit/arch/x86/kernel/tasks.c |  4 +++-
 hermit/include/hermit/tasks.h  |  4 ++++
 hermit/kernel/tasks.c          | 34 +++++++++++++++++++++-------------
 3 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/hermit/arch/x86/kernel/tasks.c b/hermit/arch/x86/kernel/tasks.c
index 0b967e21c..a013be00d 100644
--- a/hermit/arch/x86/kernel/tasks.c
+++ b/hermit/arch/x86/kernel/tasks.c
@@ -619,9 +619,11 @@ int create_user_task_form_socket(tid_t* id, int sd, uint8_t prio)
 	int len, total_len, i, j;
 	load_args_t* load_args = NULL;
 	char *dest;
-	uint32_t core_id = CORE_ID;
+	uint32_t core_id;
 	uint32_t counter = 0;
 
+	core_id = get_next_core_id();
+
 	ret = read(sd, &argc, sizeof(int));
 	if ((ret != sizeof(int)) || (argc <= 0))
 		goto out;
diff --git a/hermit/include/hermit/tasks.h b/hermit/include/hermit/tasks.h
index 492298f7d..7e094643e 100644
--- a/hermit/include/hermit/tasks.h
+++ b/hermit/include/hermit/tasks.h
@@ -206,6 +206,10 @@ int wakeup_task(tid_t);
  */
 int block_current_task(void);
 
+/** @brief Get next core_id for a new task
+ */
+uint32_t get_next_core_id(void);
+
 /** @brief Block current task until timer expires
  *
  * @param deadline Clock tick, when the timer expires
diff --git a/hermit/kernel/tasks.c b/hermit/kernel/tasks.c
index 03dd4efbe..795d4564c 100644
--- a/hermit/kernel/tasks.c
+++ b/hermit/kernel/tasks.c
@@ -261,13 +261,32 @@ void NORETURN abort(void) {
 	do_exit(-1);
 }
 
+uint32_t get_next_core_id(void)
+{
+	uint32_t i;
+	static uint32_t core_id = MAX_CORES;
+
+	if (core_id >= MAX_CORES)
+		core_id = CORE_ID;
+
+
+	// we assume OpenMP applications
+	// => number of threads is (normaly) equal to the number of cores
+	// => search next available core
+	for(i=0, core_id=(core_id+1)%MAX_CORES; i<MAX_CORES; i++, core_id=(core_id+1)%MAX_CORES)
+		if (readyqueues[core_id].idle)
+			break;
+
+	return core_id;
+}
+
 int clone_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 {
 	int ret = -EINVAL;
 	uint32_t i;
 	void* stack = NULL;
 	task_t* curr_task;
-	static uint32_t core_id = MAX_CORES;
+	uint32_t core_id;
 
 	if (BUILTIN_EXPECT(!ep, 0))
 		return -EINVAL;
@@ -275,8 +294,6 @@ int clone_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 		return -EINVAL;
 	if (BUILTIN_EXPECT(prio > MAX_PRIO, 0))
 		return -EINVAL;
-	if (BUILTIN_EXPECT(!readyqueues[core_id].idle, 0))
-		return -EINVAL;
 	if (BUILTIN_EXPECT((size_t)ep < KERNEL_SPACE, 0))
 		return -EINVAL;
 
@@ -288,16 +305,7 @@ int clone_task(tid_t* id, entry_point_t ep, void* arg, uint8_t prio)
 
 	spinlock_irqsave_lock(&table_lock);
 
-	if (core_id >= MAX_CORES)
-		core_id = CORE_ID;
-
-	// we assume OpenMP applications
-	// => number of threads is (normaly) equal to the number of cores
-	// => search next available core
-	for(i=0, core_id=(core_id+1)%MAX_CORES; i<MAX_CORES; i++, core_id=(core_id+1)%MAX_CORES)
-		if (readyqueues[core_id].idle)
-			break;
-
+	core_id = get_next_core_id();
 	if ((core_id >= MAX_CORES) || !readyqueues[core_id].idle)
 		core_id = CORE_ID;