API renaming: "llist" (lockless list) to "llstack" (lockless stack)

Index: linux-2.6-lttng/include/linux/llist.h
===================================================================
@@ -1,126 +0,0 @@
-#ifndef LLIST_H
-#define LLIST_H
-/*
- * Lock-less NULL terminated single linked list
- *
- * If there are multiple producers and multiple consumers, llist_add
- * can be used in producers and llist_del_all can be used in
- * consumers.  They can work simultaneously without lock.  But
- * llist_del_first can not be used here.  Because llist_del_first
- * depends on list->first->next does not changed if list->first is not
- * changed during its operation, but llist_del_first, llist_add,
- * llist_add (or llist_del_all, llist_add, llist_add) sequence in
- * another consumer may violate that.
- *
- * If there are multiple producers and one consumer, llist_add can be
- * used in producers and llist_del_all or llist_del_first can be used
- * in the consumer.
- *
- * This can be summarized as follow:
- *
- *           |   add    | del_first |  del_all
- * add       |    -     |     -     |     -
- * del_first |          |     L     |     L
- * del_all   |          |           |     -
- *
- * Where "-" stands for no lock is needed, while "L" stands for lock
- * is needed.
- *
- * The list entries deleted via llist_del_all can be traversed with
- * traversing function such as llist_for_each etc.  But the list
- * entries can not be traversed safely before deleted from the list.
- * The order of deleted entries is from the newest to the oldest added
- * one.  If you want to traverse from the oldest to the newest, you
- * must reverse the order by yourself before traversing.
- *
- * The basic atomic operation of this list is cmpxchg on long.  On
- * architectures that don't have NMI-safe cmpxchg implementation, the
- * list can NOT be used in NMI handler.  So code uses the list in NMI
- * handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
- */
-
-struct llist_head {
-	struct llist_node *first;
-};
-
-struct llist_node {
-	struct llist_node *next;
-};
-
-#define LLIST_HEAD_INIT(name)	{ NULL }
-#define LLIST_HEAD(name)	struct llist_head name = LLIST_HEAD_INIT(name)
-
-/**
- * init_llist_head - initialize lock-less list head
- * @head:	the head for your lock-less list
- */
-static inline void init_llist_head(struct llist_head *list)
-{
-	list->first = NULL;
-}
-
-/**
- * llist_entry - get the struct of this entry
- * @ptr:	the &struct llist_node pointer.
- * @type:	the type of the struct this is embedded in.
- * @member:	the name of the llist_node within the struct.
- */
-#define llist_entry(ptr, type, member)		\
-	container_of(ptr, type, member)
-
-/**
- * llist_for_each - iterate over some deleted entries of a lock-less list
- * @pos:	the &struct llist_node to use as a loop cursor
- * @node:	the first entry of deleted list entries
- *
- * In general, some entries of the lock-less list can be traversed
- * safely only after being deleted from list, so start with an entry
- * instead of list head.
- *
- * If being used on entries deleted from lock-less list directly, the
- * traverse order is from the newest to the oldest added entry.  If
- * you want to traverse from the oldest to the newest, you must
- * reverse the order by yourself before traversing.
- */
-#define llist_for_each(pos, node)			\
-	for ((pos) = (node); pos; (pos) = (pos)->next)
-
-/**
- * llist_for_each_entry - iterate over some deleted entries of lock-less list of given type
- * @pos:	the type * to use as a loop cursor.
- * @node:	the fist entry of deleted list entries.
- * @member:	the name of the llist_node with the struct.
- *
- * In general, some entries of the lock-less list can be traversed
- * safely only after being removed from list, so start with an entry
- * instead of list head.
- *
- * If being used on entries deleted from lock-less list directly, the
- * traverse order is from the newest to the oldest added entry.  If
- * you want to traverse from the oldest to the newest, you must
- * reverse the order by yourself before traversing.
- */
-#define llist_for_each_entry(pos, node, member)				\
-	for ((pos) = llist_entry((node), typeof(*(pos)), member);	\
-	     &(pos)->member != NULL;					\
-	     (pos) = llist_entry((pos)->member.next, typeof(*(pos)), member))
-
-/**
- * llist_empty - tests whether a lock-less list is empty
- * @head:	the list to test
- *
- * Not guaranteed to be accurate or up to date.  Just a quick way to
- * test whether the list is empty without deleting something from the
- * list.
- */
-static inline int llist_empty(const struct llist_head *head)
-{
-	return ACCESS_ONCE(head->first) == NULL;
-}
-
-void llist_add(struct llist_node *new, struct llist_head *head);
-void llist_add_batch(struct llist_node *new_first, struct llist_node *new_last,
-		     struct llist_head *head);
-struct llist_node *llist_del_first(struct llist_head *head);
-struct llist_node *llist_del_all(struct llist_head *head);
-#endif /* LLIST_H */

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Index: linux-2.6-lttng/drivers/acpi/apei/ghes.c
===================================================================
@@ -43,7 +43,7 @@
 #include <linux/ratelimit.h>
 #include <linux/vmalloc.h>
 #include <linux/irq_work.h>
-#include <linux/llist.h>
+#include <linux/llstack.h>
 #include <linux/genalloc.h>
 #include <acpi/apei.h>
 #include <acpi/atomicio.h>

@@ -105,7 +105,7 @@ struct ghes {
 };
 
 struct ghes_estatus_node {
-	struct llist_node llnode;
+	struct llstack_node llnode;
 	struct acpi_hest_generic *generic;
 };
 

@@ -168,13 +168,13 @@ static DEFINE_SPINLOCK(ghes_ioremap_lock
  * printk is not safe in NMI context.  So in NMI handler, we allocate
  * required memory from lock-less memory allocator
  * (ghes_estatus_pool), save estatus into it, put them into lock-less
- * list (ghes_estatus_llist), then delay printk into IRQ context via
+ * list (ghes_estatus_llstack), then delay printk into IRQ context via
  * irq_work (ghes_proc_irq_work).  ghes_estatus_size_request record
  * required pool size by all NMI error source.
  */
 static struct gen_pool *ghes_estatus_pool;
 static unsigned long ghes_estatus_pool_size_request;
-static struct llist_head ghes_estatus_llist;
+static struct llstack_head ghes_estatus_llstack;
 static struct irq_work ghes_proc_irq_work;
 
 struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];

@@ -712,7 +712,7 @@ static int ghes_notify_sci(struct notifi
 
 static void ghes_proc_in_irq(struct irq_work *irq_work)
 {
-	struct llist_node *llnode, *next, *tail = NULL;
+	struct llstack_node *llnode, *next, *tail = NULL;
 	struct ghes_estatus_node *estatus_node;
 	struct acpi_hest_generic *generic;
 	struct acpi_hest_generic_status *estatus;

@@ -722,7 +722,7 @@ static void ghes_proc_in_irq(struct irq_
 	 * Because the time order of estatus in list is reversed,
 	 * revert it back to proper order.
 	 */
-	llnode = llist_del_all(&ghes_estatus_llist);
+	llnode = llstack_pop_all(&ghes_estatus_llstack);
 	while (llnode) {
 		next = llnode->next;
 		llnode->next = tail;

@@ -732,8 +732,8 @@ static void ghes_proc_in_irq(struct irq_
 	llnode = tail;
 	while (llnode) {
 		next = llnode->next;
-		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
-					   llnode);
+		estatus_node = llstack_entry(llnode, struct ghes_estatus_node,
+					     llnode);
 		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
 		len = apei_estatus_len(estatus);
 		node_len = GHES_ESTATUS_NODE_LEN(len);

@@ -806,7 +806,8 @@ static int ghes_notify_nmi(struct notifi
 			estatus_node->generic = ghes->generic;
 			estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
 			memcpy(estatus, ghes->estatus, len);
-			llist_add(&estatus_node->llnode, &ghes_estatus_llist);
+			llstack_push(&estatus_node->llnode,
+				     &ghes_estatus_llstack);
 		}
 next:
 #endif

Index: linux-2.6-lttng/lib/llstack.c
===================================================================
@@ -8,6 +8,7 @@
  *
  * Copyright 2010,2011 Intel Corp.
  *   Author: Huang Ying <[email protected]>
+ * Copyright 2011 - Mathieu Desnoyers <[email protected]>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License version

@@ -33,8 +34,11 @@
  * llstack_push - push a node into a lock-less stack.
  * @new:       new entry to be added
  * @head:      the head for your lock-less stack
+ *
+ * Returns 0 if the stack was empty prior to push operation (check performed
+ * atomically with push), returns 1 otherwise.
  */
-void llstack_push(struct llstack_node *new, struct llstack_head *head)
+int llstack_push(struct llstack_node *new, struct llstack_head *head)
 {
 	struct llstack_node *entry, *old_entry;
 

@@ -48,6 +52,8 @@ void llstack_push(struct llstack_node *n
 		new->next = entry;
 		cpu_relax();
 	} while ((entry = cmpxchg(&head->first, old_entry, new)) != old_entry);
+
+	return !!(unsigned long) entry;
 }
 EXPORT_SYMBOL_GPL(llstack_push);
 

@@ -56,8 +62,11 @@ EXPORT_SYMBOL_GPL(llstack_push);
  * @new_first:	first entry in batch to be added
  * @new_last:	last entry in batch to be added
  * @head:	the head for your lock-less list
+ *
+ * Returns 0 if the stack was empty prior to push operation (check performed
+ * atomically with push), returns 1 otherwise.
  */
-void llstack_push_batch(struct llstack_node *new_first, struct llstack_node *new_last,
+int llstack_push_batch(struct llstack_node *new_first, struct llstack_node *new_last,
 			struct llstack_head *head)
 {
 	struct llstack_node *entry, *old_entry;

@@ -72,6 +81,8 @@ void llstack_push_batch(struct llstack_n
 		new_last->next = entry;
 		cpu_relax();
 	} while ((entry = cmpxchg(&head->first, old_entry, new_first)) != old_entry);
+
+	return !!(unsigned long) entry;
 }
 EXPORT_SYMBOL_GPL(llstack_push_batch);
 

Index: linux-2.6-lttng/include/linux/llstack.h
===================================================================
@@ -118,9 +118,9 @@ static inline int llstack_empty(const st
 	return ACCESS_ONCE(head->first) == NULL;
 }
 
-void llstack_push(struct llstack_node *new, struct llstack_head *head);
-void llstack_push_batch(struct llstack_node *new_first, struct llstack_node *new_last,
-			struct llstack_head *head);
+int llstack_push(struct llstack_node *new, struct llstack_head *head);
+int llstack_push_batch(struct llstack_node *new_first, struct llstack_node *new_last,
+		       struct llstack_head *head);
 struct llstack_node *llstack_pop(struct llstack_head *head);
 struct llstack_node *llstack_pop_all(struct llstack_head *head);
 #endif /* LLSTACK_H */