patch-2.3.4 linux/net/ipv4/ip_fragment.c

• Lines: 108
• Date: Wed May 26 18:14:37 1999
• Orig file: v2.3.3/linux/net/ipv4/ip_fragment.c
• Orig date: Sun Mar 21 07:22:00 1999

diff -u --recursive --new-file v2.3.3/linux/net/ipv4/ip_fragment.c linux/net/ipv4/ip_fragment.c
@@ -5,7 +5,7 @@
  *
  *		The IP fragmentation functionality.
  *		
- * Version:	$Id: ip_fragment.c,v 1.40 1999/03/20 23:58:34 davem Exp $
+ * Version:	$Id: ip_fragment.c,v 1.41 1999/05/27 00:38:07 davem Exp $
  *
  * Authors:	Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG>
  *		Alan Cox <Alan.Cox@linux.org>
@@ -71,7 +71,8 @@
 
 #define IPQ_HASHSZ	64
 
-struct ipq *ipq_hash[IPQ_HASHSZ];
+static struct ipq *ipq_hash[IPQ_HASHSZ];
+static spinlock_t ipfrag_lock = SPIN_LOCK_UNLOCKED;
 
 #define ipqhashfn(id, saddr, daddr, prot) \
 	((((id) >> 1) ^ (saddr) ^ (daddr) ^ (prot)) & (IPQ_HASHSZ - 1))
@@ -141,7 +142,9 @@
 	unsigned int hash = ipqhashfn(id, saddr, daddr, protocol);
 	struct ipq *qp;
 
-	/* Always, we are in a BH context, so no locking.  -DaveM */
+	/* We are always in BH context, and protected by the
+	 * ipfrag lock.
+	 */
 	for(qp = ipq_hash[hash]; qp; qp = qp->next) {
 		if(qp->iph->id == id		&&
 		   qp->iph->saddr == saddr	&&
@@ -158,8 +161,9 @@
  * because we completed, reassembled and processed it, or because
  * it timed out.
  *
- * This is called _only_ from BH contexts, on packet reception
- * processing and from frag queue expiration timers.  -DaveM
+ * This is called _only_ from BH contexts with the ipfrag lock held,
+ * on packet reception processing and from frag queue expiration
+ * timers.  -DaveM
  */
 static void ip_free(struct ipq *qp)
 {
@@ -197,6 +201,7 @@
 {
 	struct ipq *qp = (struct ipq *) arg;
 
+	spin_lock(&ipfrag_lock);
   	if(!qp->fragments)
         {	
 #ifdef IP_EXPIRE_DEBUG
@@ -213,10 +218,13 @@
 out:
 	/* Nuke the fragment queue. */
 	ip_free(qp);
+	spin_lock(&ipfrag_lock);
 }
 
 /* Memory limiting on fragments.  Evictor trashes the oldest 
  * fragment queue until we are back under the low threshold.
+ *
+ * We are always called in BH with the ipfrag lock held.
  */
 static void ip_evictor(void)
 {
@@ -229,9 +237,6 @@
 		struct ipq *qp;
 		if (atomic_read(&ip_frag_mem) <= sysctl_ipfrag_low_thresh)
 			return;
-		/* We are in a BH context, so these queue
-		 * accesses are safe.  -DaveM
-		 */
 		qp = ipq_hash[i];
 		if (qp) {
 			/* find the oldest queue for this hash bucket */
@@ -283,7 +288,7 @@
 	/* Add this entry to the queue. */
 	hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol);
 
-	/* We are in a BH context, no locking necessary.  -DaveM */
+	/* In a BH context and ipfrag lock is held.  -DaveM */
 	if((qp->next = ipq_hash[hash]) != NULL)
 		qp->next->pprev = &qp->next;
 	ipq_hash[hash] = qp;
@@ -421,6 +426,8 @@
 	
 	ip_statistics.IpReasmReqds++;
 
+	spin_lock(&ipfrag_lock);
+
 	/* Start by cleaning up the memory. */
 	if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh)
 		ip_evictor();
@@ -565,6 +572,7 @@
 out_freequeue:
 		ip_free(qp);
 out_skb:
+		spin_unlock(&ipfrag_lock);
 		return skb;
 	}
 
@@ -574,6 +582,7 @@
 out_timer:
 	mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time); /* ~ 30 seconds */
 out:
+	spin_unlock(&ipfrag_lock);
 	return NULL;
 
 	/*