Attachment 308274 Details for Bug 449809 – patch to wait before ending the request, if it is currently being sent.

[patch] patch to wait before ending the request, if it is currently being sent.

send_race.patch (text/plain), 3.74 KB, created by Ben Marzinski on 2008-06-03 18:25:10 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Ben Marzinski

Created: 2008-06-03 18:25:10 UTC

Size: 3.74 KB

patch

obsolete

>Index: src/gnbd.c
>===================================================================
>--- src.orig/gnbd.c
>+++ src/gnbd.c
>@@ -264,6 +264,26 @@ static const char *gnbdcmd_to_ascii(int 
> }
> #endif /* NDEBUG */
> 
>+
>+static int wait_for_send(struct request *req, struct gnbd_device *dev)
>+{
>+	DECLARE_WAITQUEUE(wait, current);
>+
>+	add_wait_queue(&dev->tx_wait, &wait);
>+	while(dev->current_request == req) {
>+		set_current_state(TASK_INTERRUPTIBLE);
>+		if (signal_pending(current)) {
>+			printk(KERN_WARNING "gnbd (pid %d: %s) wait interrupted by signal\n",
>+				current->pid, current->comm);
>+			return -EINTR;
>+		}
>+		schedule();
>+	}
>+	set_current_state(TASK_RUNNING);
>+	remove_wait_queue(&dev->tx_wait, &wait);
>+	return 0;
>+}
>+
> static void gnbd_end_request(struct request *req)
> {
> 	int uptodate = (req->errors == 0) ? 1 : 0;
>@@ -393,13 +413,14 @@ int __gnbd_send_req(struct gnbd_device *
> 			gnbdcmd_to_ascii(gnbd_cmd(req)),
> 			(unsigned long long)req->sector << 9,
> 			req->nr_sectors << 9);
>+	dev->current_request = req;
> 	result = sock_xmit(sock, 1, &request, sizeof(request),
> 			(gnbd_cmd(req) == GNBD_CMD_WRITE)? MSG_MORE: 0,
> 			can_signal);
> 	if (result < 0) {
> 		printk(KERN_ERR "%s: Send control failed (result %d)\n",
> 				dev->disk->disk_name, result);
>-		goto error_out;
>+		goto send_error_out;
> 	}
> 
> 	if (gnbd_cmd(req) == GNBD_CMD_WRITE) {
>@@ -423,14 +444,19 @@ int __gnbd_send_req(struct gnbd_device *
> 					printk(KERN_ERR "%s: Send data failed (result %d)\n",
> 							dev->disk->disk_name,
> 							result);
>-					goto error_out;
>+					goto send_error_out;
> 				}
> 			}
> 		}
> 	}
>+	dev->current_request = NULL;
>+	wake_up(&dev->tx_wait);
> 	up(&dev->tx_lock);
> 	return 0;
> 
>+send_error_out:
>+	dev->current_request = NULL;
>+	wake_up(&dev->tx_wait);
> error_out:
> 	up(&dev->tx_lock);
> 	return result;
>@@ -527,6 +553,9 @@ int gnbd_do_it(struct gnbd_device *dev)
> 				return result;
> 		}
> remove_req:
>+		result = wait_for_send(req, dev);
>+		if (result != 0)
>+			return result;
> 		spin_lock(&dev->queue_lock);
> 		list_del_init(&req->queuelist);
> 		dev->last_received = jiffies;
>@@ -539,8 +568,9 @@ remove_req:
> 	return result;
> }
> 
>-void gnbd_clear_que(struct gnbd_device *dev)
>+int gnbd_clear_que(struct gnbd_device *dev)
> {
>+	int err;
> 	struct request *req;
> 
> 	BUG_ON(dev->magic != GNBD_MAGIC);
>@@ -549,6 +579,9 @@ void gnbd_clear_que(struct gnbd_device *
> 		req = NULL;
> 		if (!list_empty(&dev->queue_head)) {
> 			req = list_entry(dev->queue_head.next, struct request, queuelist);
>+			err = wait_for_send(req, dev);
>+			if (err)
>+				return err;
> 			list_del_init(&req->queuelist);
> 		}
> 		if (req && req != &ping_req) {
>@@ -556,6 +589,8 @@ void gnbd_clear_que(struct gnbd_device *
> 			gnbd_end_request(req);
> 		}
> 	} while (req);
>+
>+	return 0;
> }
> 
> /*
>@@ -709,7 +744,9 @@ static int gnbd_ctl_ioctl(struct inode *
> 		if (down_interruptible(&dev->do_it_lock))
> 			return -EBUSY;
> 		dev->receiver_pid = -1;
>-		gnbd_clear_que(dev);
>+		error = gnbd_clear_que(dev);
>+		if (error)
>+			return error;
> 		bdev = dev->bdev;
> 		if (bdev) {
> 			blk_run_queue(dev->disk->queue);
>@@ -949,6 +986,8 @@ static int __init gnbd_init(void)
> 		INIT_LIST_HEAD(&gnbd_dev[i].queue_head);
> 		init_MUTEX(&gnbd_dev[i].tx_lock);
> 		init_MUTEX(&gnbd_dev[i].do_it_lock);
>+		init_waitqueue_head(&gnbd_dev[i].tx_wait);
>+		gnbd_dev[i].current_request = NULL;
> 		gnbd_dev[i].class_dev.class = &gnbd_class;
> 		sprintf(gnbd_dev[i].class_dev.class_id, "gnbd%d", i);
> 		err = class_device_register(&gnbd_dev[i].class_dev);
>Index: src/gnbd.h
>===================================================================
>--- src.orig/gnbd.h
>+++ src/gnbd.h
>@@ -56,6 +56,8 @@ struct gnbd_device {
> 	char name[32];
> 	unsigned long last_received;
> 	struct block_device *bdev;
>+	struct request *current_request;
>+	wait_queue_head_t tx_wait;
> };
> 
> #endif /* __KERNEL__ */

Actions: View | Diff

Attachments on bug 449809: 308274