[PATCH] (1/8) Eliminate brlock in psnap

From: Stephen Hemminger (shemminger@osdl.org)
Date: Tue Mar 11 2003 - 19:14:36 EST


The following replaces brlock with RCU in the SNAP module.

diff -urN -X dontdiff linux-2.5.64/net/802/psnap.c linux-2.5-nobrlock/net/802/psnap.c
--- linux-2.5.64/net/802/psnap.c 2003-03-11 09:08:01.000000000 -0800
+++ linux-2.5-nobrlock/net/802/psnap.c 2003-03-10 15:48:53.000000000 -0800
@@ -21,10 +21,10 @@
 #include <linux/mm.h>
 #include <linux/in.h>
 #include <linux/init.h>
-#include <linux/brlock.h>
 
 LIST_HEAD(snap_list);
 static struct llc_sap *snap_sap;
+static spinlock_t snap_lock = SPIN_LOCK_UNLOCKED;
 
 /*
  * Find a snap client by matching the 5 bytes.
@@ -34,17 +34,15 @@
         struct list_head *entry;
         struct datalink_proto *proto = NULL, *p;
 
- if (list_empty(&snap_list))
- goto out;
-
- list_for_each(entry, &snap_list) {
+ rcu_read_lock();
+ list_for_each_rcu(entry, &snap_list) {
                 p = list_entry(entry, struct datalink_proto, node);
                 if (!memcmp(p->type, desc, 5)) {
                         proto = p;
                         break;
                 }
         }
-out:
+ rcu_read_unlock();
         return proto;
 }
 
@@ -124,8 +122,7 @@
 {
         struct datalink_proto *proto = NULL;
 
- br_write_lock_bh(BR_NETPROTO_LOCK);
-
+ spin_lock_bh(&snap_lock);
         if (find_snap_client(desc))
                 goto out;
 
@@ -135,10 +132,10 @@
                 proto->rcvfunc = rcvfunc;
                 proto->header_length = 5 + 3; /* snap + 802.2 */
                 proto->request = snap_request;
- list_add(&proto->node, &snap_list);
+ list_add_rcu(&proto->node, &snap_list);
         }
 out:
- br_write_unlock_bh(BR_NETPROTO_LOCK);
+ spin_unlock_bh(&snap_lock);
         return proto;
 }
 
@@ -147,12 +144,13 @@
  */
 void unregister_snap_client(struct datalink_proto *proto)
 {
- br_write_lock_bh(BR_NETPROTO_LOCK);
+ static RCU_HEAD(snap_rcu);
 
- list_del(&proto->node);
- kfree(proto);
+ spin_lock_bh(&snap_lock);
+ list_del_rcu(&proto->node);
+ spin_unlock_bh(&snap_lock);
 
- br_write_unlock_bh(BR_NETPROTO_LOCK);
+ call_rcu(&snap_rcu, (void (*)(void *)) kfree, proto);
 }
 
 MODULE_LICENSE("GPL");

-
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This archive was generated by hypermail 2b29 : Sat Mar 15 2003 - 22:00:28 EST