patch-2.1.91 linux/net/core/skbuff.c

• Lines: 357
• Date: Thu Mar 26 14:59:02 1998
• Orig file: v2.1.90/linux/net/core/skbuff.c
• Orig date: Tue Mar 10 10:03:36 1998

diff -u --recursive --new-file v2.1.90/linux/net/core/skbuff.c linux/net/core/skbuff.c
@@ -16,6 +16,7 @@
  *					only put in the headers
  *		Ray VanTassle	:	Fixed --skb->lock in free
  *		Alan Cox	:	skb_copy copy arp field
+ *		Andi Kleen	:	slabified it.
  *
  *	NOTE:
  *		The __skb_ routines should be called with interrupts 
@@ -45,6 +46,8 @@
 #include <linux/netdevice.h>
 #include <linux/string.h>
 #include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/init.h>
 
 #include <net/ip.h>
 #include <net/protocol.h>
@@ -57,6 +60,11 @@
 #include <asm/system.h>
 
 /*
+ * Skb list spinlock
+ */
+spinlock_t skb_queue_lock = SPIN_LOCK_UNLOCKED;
+
+/*
  *	Resource tracking variables
  */
 
@@ -66,6 +74,8 @@
 
 extern atomic_t ip_frag_mem;
 
+static kmem_cache_t *skbuff_head_cache;
+
 /*
  *	Strings we don't want inline's duplicating
  */
@@ -87,138 +97,119 @@
 #endif	
 }
 
-/*
- *	Free an sk_buff. Release anything attached to the buffer.
- */
-
-void __kfree_skb(struct sk_buff *skb)
-{
-	if (skb->list)
-	 	printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
-		       "on a list (from %p).\n", __builtin_return_address(0));
-
-	dst_release(skb->dst);
-	if(skb->destructor)
-		skb->destructor(skb);
-	kfree_skbmem(skb);
-}
-
-/*
- *	Allocate a new skbuff. We do this ourselves so we can fill in a few 'private'
- *	fields and also do memory statistics to find all the [BEEP] leaks.
- *
- *	Note: For now we put the header after the data to get better cache
- *	usage. Once we have a good cache aware kmalloc this will cease
- *	to be a good idea.
+/* 	Allocate a new skbuff. We do this ourselves so we can fill in a few
+ *	'private' fields and also do memory statistics to find all the
+ *	[BEEP] leaks.
+ * 
  */
 
 struct sk_buff *alloc_skb(unsigned int size,int gfp_mask)
 {
 	struct sk_buff *skb;
-	unsigned char *bptr;
-	int len;
+	u8 *data;
 
 	if (in_interrupt() && (gfp_mask & __GFP_WAIT)) {
 		static int count = 0;
 		if (++count < 5) {
 			printk(KERN_ERR "alloc_skb called nonatomically "
 			       "from interrupt %p\n", __builtin_return_address(0));
-			gfp_mask &= ~__GFP_WAIT;
 		}
+		gfp_mask &= ~__GFP_WAIT;
 	}
 
-	/*
-	 *	FIXME: We could do with an architecture dependent
-	 *	'alignment mask'.
-	 */
-	 
-	/* Allow for alignments. Make a multiple of 16 bytes */
-	size = (size + 15) & ~15;
-	len = size;
-	
-	/* And stick the control itself on the end */
-	size += sizeof(struct sk_buff);
-	
-	/*
-	 *	Allocate some space
-	 */
-	 
-	bptr = kmalloc(size,gfp_mask);
-	if (bptr == NULL) {
-		atomic_inc(&net_fails);
-		return NULL;
-	}
-
-	/*
-	 *	Now we play a little game with the caches. Linux kmalloc is
-	 *	a bit cache dumb, in fact its just about maximally non 
-	 *	optimal for typical kernel buffers. We actually run faster
-	 *	by doing the following. Which is to deliberately put the
-	 *	skb at the _end_ not the start of the memory block.
+	/* Get the HEAD */
+	skb = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
+	if (skb == NULL) 
+		goto nohead;
+
+	/* Get the DATA. Size must match skb_add_mtu(). */
+	size = ((size + 15) & ~15); 
+	data = kmalloc(size + sizeof(atomic_t), gfp_mask);
+	if (data == NULL)
+		goto nodata;
+
+	/* Note that this counter is useless now - you can just look in the
+	 * skbuff_head entry in /proc/slabinfo. We keep it only for emergency
+	 * cases.
 	 */
 	atomic_inc(&net_allocs);
-	
-	skb = (struct sk_buff *)(bptr + size) - 1;
 
-	atomic_set(&skb->count, 1);		/* only one reference to this */
-	skb->data_skb = skb;			/* and we're our own data skb */
+	skb->truesize = size;
+
+	atomic_inc(&net_skbcount);
+
+	/* Load the data pointers. */
+	skb->head = data;
+	skb->data = data;
+	skb->tail = data;
+	skb->end = data + size;
+
+	/* Set up other state */
+	skb->len = 0;
+	skb->is_clone = 0;
+	skb->cloned = 0;
+
+	atomic_set(&skb->users, 1); 
+	atomic_set(skb_datarefp(skb), 1);
+	return skb;
+
+nodata:
+	kmem_cache_free(skbuff_head_cache, skb);
+nohead:
+	atomic_inc(&net_fails);
+	return NULL;
+}
+
+
+/*
+ *	Slab constructor for a skb head. 
+ */ 
+static inline void skb_headerinit(void *p, kmem_cache_t *cache, 
+				  unsigned long flags)
+{
+	struct sk_buff *skb = p;
 
+	skb->destructor = NULL;
 	skb->pkt_type = PACKET_HOST;	/* Default type */
 	skb->pkt_bridged = 0;		/* Not bridged */
 	skb->prev = skb->next = NULL;
 	skb->list = NULL;
 	skb->sk = NULL;
-	skb->truesize=size;
 	skb->stamp.tv_sec=0;	/* No idea about time */
 	skb->ip_summed = 0;
 	skb->security = 0;	/* By default packets are insecure */
 	skb->dst = NULL;
-	skb->destructor = NULL;
 	memset(skb->cb, 0, sizeof(skb->cb));
 	skb->priority = 0;
-	atomic_inc(&net_skbcount);
-	atomic_set(&skb->users, 1);
-
-	/* Load the data pointers. */
-	skb->head = bptr;
-	skb->data = bptr;
-	skb->tail = bptr;
-	skb->end = bptr + len;
-	skb->len = 0;
-	skb->inclone = 0;
-	return skb;
 }
 
 /*
- *	Free an skbuff by memory
+ *	Free an skbuff by memory without cleaning the state. 
  */
-
-extern inline void __kfree_skbmem(struct sk_buff *skb)
+void kfree_skbmem(struct sk_buff *skb)
 {
-	/* don't do anything if somebody still uses us */
-	if (atomic_dec_and_test(&skb->count)) {
+	if (!skb->cloned || atomic_dec_and_test(skb_datarefp(skb)))  
 		kfree(skb->head);
-		atomic_dec(&net_skbcount);
-	}
+
+	kmem_cache_free(skbuff_head_cache, skb);
+	atomic_dec(&net_skbcount);
 }
 
-void kfree_skbmem(struct sk_buff *skb)
+/*
+ *	Free an sk_buff. Release anything attached to the buffer. Clean the state.
+ */
+
+void __kfree_skb(struct sk_buff *skb)
 {
-	void * addr = skb->head;
+	if (skb->list)
+	 	printk(KERN_WARNING "Warning: kfree_skb passed an skb still "
+		       "on a list (from %p).\n", __builtin_return_address(0));
 
-	/* don't do anything if somebody still uses us */
-	if (atomic_dec_and_test(&skb->count)) {
-		int free_head = (skb->inclone != SKB_CLONE_INLINE);
-
-		/* free the skb that contains the actual data if we've clone()'d */
-		if (skb->data_skb != skb) {
-			addr = skb;
-			__kfree_skbmem(skb->data_skb);
-		}
-		if (free_head)
-			kfree(addr);
-		atomic_dec(&net_skbcount);
-	}
+	dst_release(skb->dst);
+	if(skb->destructor)
+		skb->destructor(skb);
+	skb_headerinit(skb, NULL, 0);  /* clean state */
+	kfree_skbmem(skb);
 }
 
 /*
@@ -228,32 +219,24 @@
 struct sk_buff *skb_clone(struct sk_buff *skb, int gfp_mask)
 {
 	struct sk_buff *n;
-	int inbuff = 0;
 	
-	if (!skb->inclone && skb_tailroom(skb) >= sizeof(struct sk_buff)) {
-		n = ((struct sk_buff *) skb->end) - 1;
-		skb->end -= sizeof(struct sk_buff);
-		skb->inclone = SKB_CLONE_ORIG;
-		inbuff = SKB_CLONE_INLINE;
-	} else {
-		n = kmalloc(sizeof(*n), gfp_mask);
-		if (!n)
-			return NULL;
-	}
+	n = kmem_cache_alloc(skbuff_head_cache, gfp_mask);
+	if (!n)
+		return NULL;
+
 	memcpy(n, skb, sizeof(*n));
-	atomic_set(&n->count, 1);
-	skb = skb->data_skb;
-	atomic_inc(&skb->count);
+	atomic_inc(skb_datarefp(skb));
+	skb->cloned = 1;
+       
 	atomic_inc(&net_allocs);
 	atomic_inc(&net_skbcount);
 	dst_clone(n->dst);
-	n->data_skb = skb;
+	n->cloned = 1;
 	n->next = n->prev = NULL;
 	n->list = NULL;
 	n->sk = NULL;
-	n->tries = 0;
+	n->is_clone = 1;
 	atomic_set(&n->users, 1);
-	n->inclone = inbuff;
 	n->destructor = NULL;
 	return n;
 }
@@ -287,6 +270,7 @@
 	skb_put(n,skb->len);
 	/* Copy the bytes */
 	memcpy(n->head,skb->head,skb->end-skb->head);
+	n->csum = skb->csum;
 	n->list=NULL;
 	n->sk=NULL;
 	n->when=skb->when;
@@ -302,7 +286,7 @@
 	n->ack_seq=skb->ack_seq;
 	memcpy(n->cb, skb->cb, sizeof(skb->cb));
 	n->used=skb->used;
-	n->tries=0;
+	n->is_clone=0;
 	atomic_set(&n->users, 1);
 	n->pkt_type=skb->pkt_type;
 	n->stamp=skb->stamp;
@@ -321,7 +305,7 @@
 	 *	Allocate the copy buffer
 	 */
  	 
-	n=alloc_skb(skb->truesize+newheadroom-headroom-sizeof(struct sk_buff), GFP_ATOMIC);
+	n=alloc_skb(skb->truesize+newheadroom-headroom, GFP_ATOMIC);
 	if(n==NULL)
 		return NULL;
 
@@ -352,7 +336,7 @@
  	n->end_seq=skb->end_seq;
 	n->ack_seq=skb->ack_seq;
 	n->used=skb->used;
-	n->tries=0;
+	n->is_clone=0;
 	atomic_set(&n->users, 1);
 	n->pkt_type=skb->pkt_type;
 	n->stamp=skb->stamp;
@@ -360,4 +344,28 @@
 	n->security=skb->security;
 
 	return n;
+}
+
+#if 0
+/* 
+ * 	Tune the memory allocator for a new MTU size.
+ */
+void skb_add_mtu(int mtu)
+{
+	/* Must match allocation in alloc_skb */
+	mtu = ((mtu + 15) & ~15) + sizeof(atomic_t);
+
+	kmem_add_cache_size(mtu);
+}
+#endif
+
+__initfunc(void skb_init(void))
+{
+	skbuff_head_cache = kmem_cache_create("skbuff_head_cache",
+					      sizeof(struct sk_buff),
+					      0,
+					      SLAB_HWCACHE_ALIGN,
+					      skb_headerinit, NULL);
+	if (!skbuff_head_cache)
+		panic("cannot create skbuff cache");
 }