[patch 33/56] openmosix/openmosix-kcomd_thread-spinlock-protection.patch

Index: linux/hpc/kcomd.c
===================================================================
--- linux.orig/hpc/kcomd.c	2006-11-02 22:52:08.000000000 +0100
+++ linux/hpc/kcomd.c	2006-11-02 22:52:22.000000000 +0100
@@ -448,7 +448,7 @@
 	siginfo_t info; /* matt*/
 	int sig;
 	int err;
-	struct timeval start,stop;
+	struct timeval;
 
 	fd4=-1;
 	fd6=-1;
@@ -465,9 +465,6 @@
 	sigfillset(&current->blocked);
 
 	/* kcom_pid=current->pid;*/
-	/* read_lock(&tasklist_lock);*/
-	/* kcomd_task = find_task_by_pid(current->pid);*/
-	/* read_unlock(&tasklist_lock);*/
 	kcomd_task=current;
 
 retry_listen:
@@ -498,42 +495,38 @@
 		if (fd6!=-1)
 			set_bit(fd6, sockets_fds.in);
 
-		/* for each nodes (set fds.in && fds.out) */
-		/* printk("spin_lock\n");*/
-		/* spin_lock(&kcom_nodes_lock);*/
-		/* printk("Setting bits for select (n=%d, maxfds=%d).\n", n, maxfds);*/
-	do_gettimeofday(&start);
+		/* for each nodes (set fds.in && fds.out) and reset the waiting fds */
+
+		read_lock(&kcom_nodes_lock);
 		list_for_each_entry(node, &kcom_nodes, list) {
 			/* printk("node->fd=%d\n", node->fd);*/
 
 			if (node->fd == -1 || node->fd > maxfds) {
-				/* spin_unlock(&kcom_nodes_lock);*/
+				read_unlock(&kcom_nodes_lock);
 				continue;
 			}
 
 			/* if a file descriptor is open, we want select to pay attention.*/
-			/* printk("Setting in bit for fd%d\n", node->fd);*/
 			set_bit(node->fd, sockets_fds.in);
 			set_bit(node->fd, sockets_fds.ex);
 
 			/* if there are packets to be sent, select should pay attention.*/
+			read_lock(&node->tasks_lock);
 			list_for_each_entry(task, &node->tasks, list)
 				if (!list_empty(&task->out_packs)) {
-					/* printk("Setting out bit for fd%d\n", node->fd);*/
 					set_bit(node->fd, sockets_fds.out);
 				}
+			read_unlock(&node->task_locks);
 		}
-	do_gettimeofday(&stop);
-		/* spin_unlock(&kcom_nodes_lock);*/
-		/* printk("Done setting bits for select.\n");*/
-
-
+		read_unlock(&kcom_nodes_lock);
 
 		zero_fd_set(n, sockets_fds.res_in);
 		zero_fd_set(n, sockets_fds.res_out);
 		zero_fd_set(n, sockets_fds.res_ex);
 
-	do_gettimeofday(&start);
+
+		/* Now wait for a signal or packet to arrive */
+
 		allow_signal (SIGHUP);
 		timeout=-1;
 		ret = do_select(n + 1, &sockets_fds, &timeout);
@@ -547,18 +540,20 @@
 			/* We have to allocate them here.*/
 			/* We'll do that for the signal so we don't have to do it every iteration.*/
 
+			read_lock(&kcom_nodes_lock);
 			list_for_each_entry(node, &kcom_nodes, list)
 				if (node->fd==0) { /* unmapped*/
-					/* printk("Found unmapped socket\n");*/
 					node->fd = sock_map_fd(node->sock);
 					alloc_fd_bitmap(node->fd);
 				}
+			read_unlock(&kcom_nodes_lock);
+
 			continue;
+
 		} else if (ret < 0) {/* -1=error; 0=signal*/
 			printk(KERN_ERR "do_select returned an error. \n");
 			schedule_timeout_interruptible(HZ);
 		}
-	do_gettimeofday(&stop);
 
 		/* test listening sockets */
 		if (fd4 != -1 && test_bit(fd4, sockets_fds.res_in)) {