From 28eb6490565c9e6562e7047e0a59ef51e11b2ff2 Mon Sep 17 00:00:00 2001
From: Balazs Gerofi <bgerofi@riken.jp>
Date: Sun, 20 Aug 2017 09:44:48 +0900
Subject: [PATCH] Generic lock-free kmalloc cache implementation

Conflicts:
	kernel/mem.c
---
 kernel/include/kmalloc.h |  9 +++++++
 kernel/mem.c             | 57 ++++++++++++++++++++++++++++++++++++++++
 kernel/process.c         |  1 -
 3 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/kernel/include/kmalloc.h b/kernel/include/kmalloc.h
index 4574486b..c97feede 100644
--- a/kernel/include/kmalloc.h
+++ b/kernel/include/kmalloc.h
@@ -19,6 +19,15 @@
 void panic(const char *);
 int kprintf(const char *format, ...);
 
+struct kmalloc_cache_header {
+	struct kmalloc_cache_header *next;
+};
+
+void *kmalloc_cache_alloc(struct kmalloc_cache_header *cache,
+		size_t size);
+void kmalloc_cache_free(struct kmalloc_cache_header *cache,
+		void *elem);
+
 #define kmalloc(size, flag) ({\
 void *r = _kmalloc(size, flag, __FILE__, __LINE__);\
 if(r == NULL){\
diff --git a/kernel/mem.c b/kernel/mem.c
index fc1c4c01..5d987f08 100644
--- a/kernel/mem.c
+++ b/kernel/mem.c
@@ -2611,3 +2611,60 @@ int ihk_mc_get_mem_user_page(void *arg0, page_table_t pt, pte_t *ptep, void *pga
 
 	return 0;
 }
+
+/*
+ * Generic lockless kmalloc cache.
+ */
+void *kmalloc_cache_alloc(struct kmalloc_cache_header *cache,
+		size_t size)
+{
+	struct kmalloc_cache_header *first, *next;
+
+retry:
+	next = NULL;
+	first = cache->next;
+
+	if (first) {
+		next = first->next;
+
+		if (!__sync_bool_compare_and_swap(&cache->next,
+					first, next)) {
+			goto retry;
+		}
+	}
+	else {
+		int i;
+		kprintf("%s: cache empty, allocating ...\n", __FUNCTION__);
+		for (i = 0; i < 100; ++i) {
+			first = (struct kmalloc_cache_header *)
+				kmalloc(size, IHK_MC_AP_NOWAIT);
+
+			if (!first) {
+				kprintf("%s: ERROR: allocating cache element\n", __FUNCTION__);
+				continue;
+			}
+
+			kmalloc_cache_free(cache, first);
+		}
+
+		goto retry;
+	}
+
+	return (void *)first;
+}
+
+void kmalloc_cache_free(struct kmalloc_cache_header *cache, void *elem)
+{
+	struct kmalloc_cache_header *current = NULL;
+	struct kmalloc_cache_header *new =
+		(struct kmalloc_cache_header *)elem;
+
+retry:
+	current = cache->next;
+	new->next = current;
+
+	if (!__sync_bool_compare_and_swap(&cache->next, current, new)) {
+		goto retry;
+	}
+}
+
diff --git a/kernel/process.c b/kernel/process.c
index c97c57a1..7c9afaf4 100644
--- a/kernel/process.c
+++ b/kernel/process.c
@@ -138,7 +138,6 @@ init_process(struct process *proc, struct process *parent)
 	INIT_LIST_HEAD(&proc->ptraced_siblings_list);
 	mcs_rwlock_init(&proc->update_lock);
 #endif /* POSTK_DEBUG_ARCH_DEP_63 */
-	}
 
 	// Double check the inheritance from parent
 	memset(proc->fd_priv_table, 0, 256 * sizeof(void *));