From: Alex Nixon <alex.nixon@citrix.com>
Date: Thu, 21 Aug 2008 12:30:54 +0100
Subject: [PATCH] Xen: Fix warning when hot-unplugging virtual block devices
WARNING: at kernel/softirq.c:136 local_bh_enable+0x3f/0x8a()
del_gendisk needs IRQs enabled, as the code path eventually reaches local_bh_enable.
blk_stop_queue needs them disabled - so do so temporarily.
It shouldn't matter if an interrupt comes in whilst blkif_io_lock is held, as it will block on the lock. Upon acquisition, it'll realise the device is down and exit cleanly.
Signed-off-by: Alex Nixon <alex.nixon@citrix.com>
---
drivers/block/xen-blkfront.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index d5e7532..95cee2c 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -899,16 +899,18 @@ static void blkfront_closing(struct xenbus_device *dev)
if (info->rq == NULL)
goto out;
- spin_lock_irqsave(&blkif_io_lock, flags);
+ spin_lock(&blkif_io_lock);
del_gendisk(info->gd);
+ local_irq_save(flags);
/* No more blkif_request(). */
blk_stop_queue(info->rq);
+ local_irq_restore(flags);
/* No more gnttab callback work. */
gnttab_cancel_free_callback(&info->callback);
- spin_unlock_irqrestore(&blkif_io_lock, flags);
+ spin_unlock(&blkif_io_lock);
/* Flush gnttab callback work. Must be done with no locks held. */
flush_scheduled_work();
--
1.5.4.3
--
