[Tipc-discussion] patch for socket.c

[Mark H. <ma...@os...>]

I found a race using tipc_queue_size.  Multiple processors can be
accessing the variable at the same time causing it to become corrupted. 
I was seeing places where the tipc_queue_size was already zero but being
decremented.  This caused all kinds of strange things to happen. Anyway,
I converted tipc_queue_size to an atomic_t to protect access to the
variable.  I can now run the tipc benchmark client/server test without
hanging the network and/or computer.

Index: socket.c
===================================================================
RCS file: /cvsroot/tipc/source/unstable/net/tipc/linux-2.6/socket.c,v
retrieving revision 1.3
diff -u -r1.3 socket.c
--- socket.c	15 Apr 2004 18:06:37 -0000	1.3
+++ socket.c	19 Apr 2004 21:50:19 -0000
@@ -99,6 +99,7 @@
 #include <linux/version.h>
 #include <asm/semaphore.h>
 #include <asm/string.h>
+#include <asm/atomic.h>
 #include <linux/fcntl.h>
 #include "tipc_adapt.h"
 #include <tipc_msg.h>
@@ -133,7 +134,7 @@
         int  buf_rest;
 };
 
-static uint tipc_queue_size = 0;
+static atomic_t tipc_queue_size = ATOMIC_INIT(0);
 extern wait_queue_head_t tipc_signal_wq;
 static uint dispatch(struct tipc_port*,struct sk_buff *buf);
 static void wakeupdispatch(struct tipc_port *port);
@@ -193,8 +194,8 @@
         pmask |= pollmask(tsock->queue_head);
         tsock->pollmask = pmask;
 	tsock->queue_size--;
-	tipc_queue_size--;
         spin_unlock_bh(tsock->p->lock);
+	atomic_dec(&tipc_queue_size);
 	if (unlikely(pmask & POLLHUP))
 		tipc_disconnect(tsock->p->ref);
 }
@@ -284,7 +285,7 @@
 		struct sk_buff *next = buf_next(buf);
 		tipc_reject_msg(buf, TIPC_ERR_NO_PORT);
 		buf = next;
-		tipc_queue_size--;
+		atomic_dec(&tipc_queue_size);
 	}
 
 	while (tsock->ev_head) {
@@ -371,7 +372,7 @@
                 /* Remove for next poll/read */
 		tsock->pollmask &= ~MSG_ERROR;	
                 /* Empty error msg?  */
-		if (!(pmask & TIPC_MSG_PENDING)) 
+		if (!(pmask & TIPC_MSG_PENDING))
                         advance_queue(tsock);
 	}
 	return pmask;
@@ -760,14 +761,16 @@
 	uint pmask = 0;
         uint res = TIPC_OK;;
 
-	if (unlikely(tipc_queue_size > OVERLOAD_LIMIT_BASE)) {
-		if (overload(tipc_queue_size, OVERLOAD_LIMIT_BASE, msg)){
+	if (unlikely((uint)atomic_read(&tipc_queue_size) > 
+						OVERLOAD_LIMIT_BASE)) {
+		if (overload(atomic_read(&tipc_queue_size), 
+					OVERLOAD_LIMIT_BASE, msg)){
 			res = TIPC_ERR_OVERLOAD;
                         goto error;
                 }
         }
 	if (unlikely(tsock->queue_size > OVERLOAD_LIMIT_BASE / 2)) {
-		if (overload(tsock->queue_size, OVERLOAD_LIMIT_BASE / 2, msg)){
+		if (overload(tsock->queue_size, OVERLOAD_LIMIT_BASE / 2, msg)) {
 			res = TIPC_ERR_OVERLOAD;
                         goto error;
                 }
@@ -779,7 +782,7 @@
                 }
         }
 	tsock->queue_size += 1;
-	tipc_queue_size += 1;
+	atomic_inc(&tipc_queue_size);
 	msg_dbg(msg,"<DISP<: ");
 	buf_set_next(buf, 0);
 	if (tsock->queue_head) {


-- 
Mark Haverkamp <ma...@os...>