[PATCH] small skbuff.[ch] tweaks

[Mitchell Blank Jr <mitch@xxxxxxxxxx>]

This patch:
  o Makes a couple inline functions in <linux/skbuff.h> take const arguments
    as appropriate
  o Obvious unlikely()/likely()/BUG_ON() conversions

Patch is versus 2.6.0-test4.

-Mitch

--- linux-2.6.0-test4-VIRGIN/include/linux/skbuff.h     2003-08-10 
05:28:41.000000000 -0700
+++ linux-2.6.0-test4mnb1/include/linux/skbuff.h        2003-09-01 
14:08:54.000000000 -0700
@@ -306,7 +306,7 @@
  *
  *     Returns true if the queue is empty, false otherwise.
  */
-static inline int skb_queue_empty(struct sk_buff_head *list)
+static inline int skb_queue_empty(const struct sk_buff_head *list)
 {
        return list->next == (struct sk_buff *)list;
 }
@@ -475,7 +475,7 @@
  *
  *     Return the length of an &sk_buff queue.
  */
-static inline __u32 skb_queue_len(struct sk_buff_head *list_)
+static inline __u32 skb_queue_len(const struct sk_buff_head *list_)
 {
        return list_->qlen;
 }
@@ -1050,7 +1050,7 @@
                                              int gfp_mask)
 {
        struct sk_buff *skb = alloc_skb(length + 16, gfp_mask);
-       if (skb)
+       if (likely(skb))
                skb_reserve(skb, 16);
        return skb;
 }
--- linux-2.6.0-test4-VIRGIN/net/core/skbuff.c  2003-08-22 13:47:28.000000000 
-0700
+++ linux-2.6.0-test4mnb1/net/core/skbuff.c     2003-09-01 14:00:37.000000000 
-0700
@@ -129,14 +129,17 @@
        /* Get the HEAD */
        skb = kmem_cache_alloc(skbuff_head_cache,
                               gfp_mask & ~__GFP_DMA);
-       if (!skb)
+       if (unlikely(!skb))
                goto out;
 
        /* Get the DATA. Size must match skb_add_mtu(). */
        size = SKB_DATA_ALIGN(size);
        data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
-       if (!data)
-               goto nodata;
+       if (unlikely(!data)) {
+               kmem_cache_free(skbuff_head_cache, skb);
+               skb = NULL;
+               goto out;
+       }
 
        memset(skb, 0, offsetof(struct sk_buff, truesize));
        skb->truesize = size + sizeof(struct sk_buff);
@@ -153,10 +156,6 @@
        skb_shinfo(skb)->frag_list = NULL;
 out:
        return skb;
-nodata:
-       kmem_cache_free(skbuff_head_cache, skb);
-       skb = NULL;
-       goto out;
 }
 
 
@@ -218,7 +217,7 @@
 
 void __kfree_skb(struct sk_buff *skb)
 {
-       if (skb->list) {
+       if (unlikely(skb->list)) {
                printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
                       "on a list (from %p).\n", NET_CALLER(skb));
                BUG();
@@ -229,7 +228,7 @@
        secpath_put(skb->sp);
 #endif
        if(skb->destructor) {
-               if (in_irq())
+               if (unlikely(in_irq()))
                        printk(KERN_WARNING "Warning: kfree_skb on "
                                            "hard IRQ %p\n", NET_CALLER(skb));
                skb->destructor(skb);
@@ -261,7 +260,7 @@
 {
        struct sk_buff *n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
 
-       if (!n) 
+       if (unlikely(!n))
                return NULL;
 
 #define C(x) n->x = skb->x
@@ -395,7 +394,7 @@
         */
        struct sk_buff *n = alloc_skb(skb->end - skb->head + skb->data_len,
                                      gfp_mask);
-       if (!n)
+       if (unlikely(!n))
                return NULL;
 
        /* Set the data pointer */
@@ -405,7 +404,7 @@
        n->csum      = skb->csum;
        n->ip_summed = skb->ip_summed;
 
-       if (skb_copy_bits(skb, -headerlen, n->head, headerlen + skb->len))
+       if (unlikely(skb_copy_bits(skb, -headerlen, n->head, headerlen + 
skb->len)))
                BUG();
 
        copy_skb_header(n, skb);
@@ -433,7 +432,7 @@
         */
        struct sk_buff *n = alloc_skb(skb->end - skb->head, gfp_mask);
 
-       if (!n)
+       if (unlikely(!n))
                goto out;
 
        /* Set the data pointer */
@@ -493,14 +492,13 @@
        int size = nhead + (skb->end - skb->head) + ntail;
        long off;
 
-       if (skb_shared(skb))
-               BUG();
+       BUG_ON(skb_shared(skb));
 
        size = SKB_DATA_ALIGN(size);
 
        data = kmalloc(size + sizeof(struct skb_shared_info), gfp_mask);
-       if (!data)
-               goto nodata;
+       if (unlikely(!data))
+               return -ENOMEM;
 
        /* Copy only real data... and, alas, header. This should be
         * optimized for the cases when header is void. */
@@ -527,9 +525,6 @@
        skb->cloned   = 0;
        atomic_set(&skb_shinfo(skb)->dataref, 1);
        return 0;
-
-nodata:
-       return -ENOMEM;
 }
 
 /* Make private copy of skb with writable head and some headroom */
@@ -543,8 +538,8 @@
                skb2 = pskb_copy(skb, GFP_ATOMIC);
        else {
                skb2 = skb_clone(skb, GFP_ATOMIC);
-               if (skb2 && pskb_expand_head(skb2, SKB_DATA_ALIGN(delta), 0,
-                                            GFP_ATOMIC)) {
+               if (unlikely(skb2 && pskb_expand_head(skb2,
+                               SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC))) {
                        kfree_skb(skb2);
                        skb2 = NULL;
                }
@@ -582,7 +577,7 @@
         */
        struct sk_buff *n = alloc_skb(newheadroom + skb->len + newtailroom,
                                      gfp_mask);
-       if (!n)
+       if (unlikely(!n))
                return NULL;
 
        skb_reserve(n, newheadroom);
@@ -591,7 +586,7 @@
        skb_put(n, skb->len);
 
        /* Copy the data only. */
-       if (skb_copy_bits(skb, 0, n->data, skb->len))
+       if (unlikely(skb_copy_bits(skb, 0, n->data, skb->len)))
                BUG();
 
        copy_skb_header(n, skb);
@@ -625,7 +620,7 @@
        
        nskb = skb_copy_expand(skb, skb_headroom(skb), skb_tailroom(skb) + pad, 
GFP_ATOMIC);
        kfree_skb(skb);
-       if (nskb)
+       if (likely(nskb))
                memset(nskb->data+nskb->len, 0, pad);
        return nskb;
 }      
@@ -645,9 +640,8 @@
                int end = offset + skb_shinfo(skb)->frags[i].size;
                if (end > len) {
                        if (skb_cloned(skb)) {
-                               if (!realloc)
-                                       BUG();
-                               if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
+                               BUG_ON(!realloc);
+                               if (unlikely(pskb_expand_head(skb, 0, 0, 
GFP_ATOMIC)))
                                        return -ENOMEM;
                        }
                        if (len <= offset) {
@@ -713,12 +707,12 @@
        int i, k, eat = (skb->tail + delta) - skb->end;
 
        if (eat > 0 || skb_cloned(skb)) {
-               if (pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
-                                    GFP_ATOMIC))
+               if (unlikely(pskb_expand_head(skb, 0, eat > 0 ? eat + 128 : 0,
+                                    GFP_ATOMIC)))
                        return NULL;
        }
 
-       if (skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta))
+       if (unlikely(skb_copy_bits(skb, skb_headlen(skb), skb->tail, delta)))
                BUG();
 
        /* Optimization: no fragments, no reasons to preestimate
@@ -748,8 +742,7 @@
                struct sk_buff *insp = NULL;
 
                do {
-                       if (!list)
-                               BUG();
+                       BUG_ON(!list);
 
                        if (list->len <= eat) {
                                /* Eaten as whole. */
@@ -762,7 +755,7 @@
                                if (skb_shared(list)) {
                                        /* Sucks! We need to fork list. :-( */
                                        clone = skb_clone(list, GFP_ATOMIC);
-                                       if (!clone)
+                                       if (unlikely(!clone))
                                                return NULL;
                                        insp = list->next;
                                        list = clone;
@@ -771,7 +764,7 @@
                                         * problems. */
                                        insp = list;
                                }
-                               if (!pskb_pull(list, eat)) {
+                               if (unlikely(!pskb_pull(list, eat))) {
                                        if (clone)
                                                kfree_skb(clone);
                                        return NULL;
@@ -825,7 +818,7 @@
        int i, copy;
        int start = skb_headlen(skb);
 
-       if (offset > (int)skb->len - len)
+       if (unlikely(offset > (int)skb->len - len))
                goto fault;
 
        /* Copy header. */
@@ -877,8 +870,8 @@
                        if ((copy = end - offset) > 0) {
                                if (copy > len)
                                        copy = len;
-                               if (skb_copy_bits(list, offset - start,
-                                                 to, copy))
+                               if (unlikely(skb_copy_bits(list, offset - start,
+                                                 to, copy)))
                                        goto fault;
                                if ((len -= copy) == 0)
                                        return 0;
@@ -888,7 +881,7 @@
                        start = end;
                }
        }
-       if (!len)
+       if (likely(!len))
                return 0;
 
 fault:
@@ -965,8 +958,7 @@
                        start = end;
                }
        }
-       if (len)
-               BUG();
+       BUG_ON(len);
 
        return csum;
 }
@@ -1048,8 +1040,7 @@
                        start = end;
                }
        }
-       if (len)
-               BUG();
+       BUG_ON(len);
        return csum;
 }
 
@@ -1063,8 +1054,7 @@
        else
                csstart = skb_headlen(skb);
 
-       if (csstart > skb_headlen(skb))
-               BUG();
+       BUG_ON(csstart > skb_headlen(skb));
 
        memcpy(to, skb->data, csstart);