net, rds, Replace xlist in net/rds/xlist.h with llist

The functionality of xlist and llist is almost same.  This patch
replace xlist with llist to avoid code duplication.

Known issues: don't know how to test this, need special hardware?

Signed-off-by: Huang Ying <ying.huang@intel.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Andy Grover <andy.grover@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 52 insertions, 141 deletions

diff --git a/net/rds/Kconfig b/net/rds/Kconfig
index ec753b3ae72a..4cf6dc7910e4 100644
--- a/net/rds/Kconfig
+++ b/net/rds/Kconfig
@@ -9,6 +9,7 @@ config RDS
 
 config RDS_RDMA
         tristate "RDS over Infiniband and iWARP"
+        select LLIST
         depends on RDS && INFINIBAND && INFINIBAND_ADDR_TRANS
         ---help---
           Allow RDS to use Infiniband and iWARP as a transport.
diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
index 819c35a0d9cb..e8fdb172adbb 100644
--- a/net/rds/ib_rdma.c
+++ b/net/rds/ib_rdma.c
@@ -33,10 +33,10 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/rculist.h>
+#include <linux/llist.h>
 
 #include "rds.h"
 #include "ib.h"
-#include "xlist.h"
 
 static DEFINE_PER_CPU(unsigned long, clean_list_grace);
 #define CLEAN_LIST_BUSY_BIT 0
@@ -49,7 +49,7 @@ struct rds_ib_mr {
         struct rds_ib_mr_pool   *pool;
         struct ib_fmr           *fmr;
 
-        struct xlist_head       xlist;
+        struct llist_node       llnode;
 
         /* unmap_list is for freeing */
         struct list_head        unmap_list;
@@ -71,9 +71,9 @@ struct rds_ib_mr_pool {
         atomic_t                item_count;             /* total # of MRs */
         atomic_t                dirty_count;            /* # dirty of MRs */
 
-        struct xlist_head       drop_list;              /* MRs that have reached their max_maps limit */
-        struct xlist_head       free_list;              /* unused MRs */
-        struct xlist_head       clean_list;             /* global unused & unamapped MRs */
+        struct llist_head       drop_list;              /* MRs that have reached their max_maps limit */
+        struct llist_head       free_list;              /* unused MRs */
+        struct llist_head       clean_list;             /* global unused & unamapped MRs */
         wait_queue_head_t       flush_wait;
 
         atomic_t                free_pinned;            /* memory pinned by free MRs */
@@ -220,9 +220,9 @@ struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev)
         if (!pool)
                 return ERR_PTR(-ENOMEM);
 
-        INIT_XLIST_HEAD(&pool->free_list);
-        INIT_XLIST_HEAD(&pool->drop_list);
-        INIT_XLIST_HEAD(&pool->clean_list);
+        init_llist_head(&pool->free_list);
+        init_llist_head(&pool->drop_list);
+        init_llist_head(&pool->clean_list);
         mutex_init(&pool->flush_lock);
         init_waitqueue_head(&pool->flush_wait);
         INIT_DELAYED_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
@@ -260,26 +260,18 @@ void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
         kfree(pool);
 }
 
-static void refill_local(struct rds_ib_mr_pool *pool, struct xlist_head *xl,
-                         struct rds_ib_mr **ibmr_ret)
-{
-        struct xlist_head *ibmr_xl;
-        ibmr_xl = xlist_del_head_fast(xl);
-        *ibmr_ret = list_entry(ibmr_xl, struct rds_ib_mr, xlist);
-}
-
 static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool)
 {
         struct rds_ib_mr *ibmr = NULL;
-        struct xlist_head *ret;
+        struct llist_node *ret;
         unsigned long *flag;
 
         preempt_disable();
         flag = &__get_cpu_var(clean_list_grace);
         set_bit(CLEAN_LIST_BUSY_BIT, flag);
-        ret = xlist_del_head(&pool->clean_list);
+        ret = llist_del_first(&pool->clean_list);
         if (ret)
-                ibmr = list_entry(ret, struct rds_ib_mr, xlist);
+                ibmr = llist_entry(ret, struct rds_ib_mr, llnode);
 
         clear_bit(CLEAN_LIST_BUSY_BIT, flag);
         preempt_enable();
@@ -529,46 +521,44 @@ static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int fr
 }
 
 /*
- * given an xlist of mrs, put them all into the list_head for more processing
+ * given an llist of mrs, put them all into the list_head for more processing
  */
-static void xlist_append_to_list(struct xlist_head *xlist, struct list_head *list)
+static void llist_append_to_list(struct llist_head *llist, struct list_head *list)
 {
         struct rds_ib_mr *ibmr;
-        struct xlist_head splice;
-        struct xlist_head *cur;
-        struct xlist_head *next;
-
-        splice.next = NULL;
-        xlist_splice(xlist, &splice);
-        cur = splice.next;
-        while (cur) {
-                next = cur->next;
-                ibmr = list_entry(cur, struct rds_ib_mr, xlist);
+        struct llist_node *node;
+        struct llist_node *next;
+
+        node = llist_del_all(llist);
+        while (node) {
+                next = node->next;
+                ibmr = llist_entry(node, struct rds_ib_mr, llnode);
                 list_add_tail(&ibmr->unmap_list, list);
-                cur = next;
+                node = next;
         }
 }
 
 /*
- * this takes a list head of mrs and turns it into an xlist of clusters.
- * each cluster has an xlist of MR_CLUSTER_SIZE mrs that are ready for
- * reuse.
+ * this takes a list head of mrs and turns it into linked llist nodes
+ * of clusters.  Each cluster has linked llist nodes of
+ * MR_CLUSTER_SIZE mrs that are ready for reuse.
  */
-static void list_append_to_xlist(struct rds_ib_mr_pool *pool,
-                                struct list_head *list, struct xlist_head *xlist,
-                                struct xlist_head **tail_ret)
+static void list_to_llist_nodes(struct rds_ib_mr_pool *pool,
+                                struct list_head *list,
+                                struct llist_node **nodes_head,
+                                struct llist_node **nodes_tail)
 {
         struct rds_ib_mr *ibmr;
-        struct xlist_head *cur_mr = xlist;
-        struct xlist_head *tail_mr = NULL;
+        struct llist_node *cur = NULL;
+        struct llist_node **next = nodes_head;
 
         list_for_each_entry(ibmr, list, unmap_list) {
-                tail_mr = &ibmr->xlist;
-                tail_mr->next = NULL;
-                cur_mr->next = tail_mr;
-                cur_mr = tail_mr;
+                cur = &ibmr->llnode;
+                *next = cur;
+                next = &cur->next;
         }
-        *tail_ret = tail_mr;
+        *next = NULL;
+        *nodes_tail = cur;
 }
 
 /*
@@ -581,8 +571,8 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
                                 int free_all, struct rds_ib_mr **ibmr_ret)
 {
         struct rds_ib_mr *ibmr, *next;
-        struct xlist_head clean_xlist;
-        struct xlist_head *clean_tail;
+        struct llist_node *clean_nodes;
+        struct llist_node *clean_tail;
         LIST_HEAD(unmap_list);
         LIST_HEAD(fmr_list);
         unsigned long unpinned = 0;
@@ -603,7 +593,7 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
 
                         prepare_to_wait(&pool->flush_wait, &wait,
                                         TASK_UNINTERRUPTIBLE);
-                        if (xlist_empty(&pool->clean_list))
+                        if (llist_empty(&pool->clean_list))
                                 schedule();
 
                         ibmr = rds_ib_reuse_fmr(pool);
@@ -628,10 +618,10 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
         /* Get the list of all MRs to be dropped. Ordering matters -
          * we want to put drop_list ahead of free_list.
          */
-        xlist_append_to_list(&pool->drop_list, &unmap_list);
-        xlist_append_to_list(&pool->free_list, &unmap_list);
+        llist_append_to_list(&pool->drop_list, &unmap_list);
+        llist_append_to_list(&pool->free_list, &unmap_list);
         if (free_all)
-                xlist_append_to_list(&pool->clean_list, &unmap_list);
+                llist_append_to_list(&pool->clean_list, &unmap_list);
 
         free_goal = rds_ib_flush_goal(pool, free_all);
 
@@ -663,22 +653,22 @@ static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
         if (!list_empty(&unmap_list)) {
                 /* we have to make sure that none of the things we're about
                  * to put on the clean list would race with other cpus trying
-                 * to pull items off.  The xlist would explode if we managed to
+                 * to pull items off.  The llist would explode if we managed to
                  * remove something from the clean list and then add it back again
-                 * while another CPU was spinning on that same item in xlist_del_head.
+                 * while another CPU was spinning on that same item in llist_del_first.
                  *
-                 * This is pretty unlikely, but just in case  wait for an xlist grace period
+                 * This is pretty unlikely, but just in case  wait for an llist grace period
                  * here before adding anything back into the clean list.
                  */
                 wait_clean_list_grace();
 
-                list_append_to_xlist(pool, &unmap_list, &clean_xlist, &clean_tail);
+                list_to_llist_nodes(pool, &unmap_list, &clean_nodes, &clean_tail);
                 if (ibmr_ret)
-                        refill_local(pool, &clean_xlist, ibmr_ret);
+                        *ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);
 
-                /* refill_local may have emptied our list */
-                if (!xlist_empty(&clean_xlist))
-                        xlist_add(clean_xlist.next, clean_tail, &pool->clean_list);
+                /* more than one entry in llist nodes */
+                if (clean_nodes->next)
+                        llist_add_batch(clean_nodes->next, clean_tail, &pool->clean_list);
 
         }
 
@@ -711,9 +701,9 @@ void rds_ib_free_mr(void *trans_private, int invalidate)
 
         /* Return it to the pool's free list */
         if (ibmr->remap_count >= pool->fmr_attr.max_maps)
-                xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->drop_list);
+                llist_add(&ibmr->llnode, &pool->drop_list);
         else
-                xlist_add(&ibmr->xlist, &ibmr->xlist, &pool->free_list);
+                llist_add(&ibmr->llnode, &pool->free_list);
 
         atomic_add(ibmr->sg_len, &pool->free_pinned);
         atomic_inc(&pool->dirty_count);
diff --git a/net/rds/xlist.h b/net/rds/xlist.h
deleted file mode 100644
index e6b5190daddd..000000000000
--- a/net/rds/xlist.h
+++ /dev/null
@@ -1,80 +0,0 @@
-#ifndef _LINUX_XLIST_H
-#define _LINUX_XLIST_H
-
-#include <linux/stddef.h>
-#include <linux/poison.h>
-#include <linux/prefetch.h>
-#include <asm/system.h>
-
-struct xlist_head {
-        struct xlist_head *next;
-};
-
-static inline void INIT_XLIST_HEAD(struct xlist_head *list)
-{
-        list->next = NULL;
-}
-
-static inline int xlist_empty(struct xlist_head *head)
-{
-        return head->next == NULL;
-}
-
-static inline void xlist_add(struct xlist_head *new, struct xlist_head *tail,
-                             struct xlist_head *head)
-{
-        struct xlist_head *cur;
-        struct xlist_head *check;
-
-        while (1) {
-                cur = head->next;
-                tail->next = cur;
-                check = cmpxchg(&head->next, cur, new);
-                if (check == cur)
-                        break;
-        }
-}
-
-static inline struct xlist_head *xlist_del_head(struct xlist_head *head)
-{
-        struct xlist_head *cur;
-        struct xlist_head *check;
-        struct xlist_head *next;
-
-        while (1) {
-                cur = head->next;
-                if (!cur)
-                        goto out;
-
-                next = cur->next;
-                check = cmpxchg(&head->next, cur, next);
-                if (check == cur)
-                        goto out;
-        }
-out:
-        return cur;
-}
-
-static inline struct xlist_head *xlist_del_head_fast(struct xlist_head *head)
-{
-        struct xlist_head *cur;
-
-        cur = head->next;
-        if (!cur)
-                return NULL;
-
-        head->next = cur->next;
-        return cur;
-}
-
-static inline void xlist_splice(struct xlist_head *list,
-                                struct xlist_head *head)
-{
-        struct xlist_head *cur;
-
-        WARN_ON(head->next);
-        cur = xchg(&list->next, NULL);
-        head->next = cur;
-}
-
-#endif