This is a note to let you know that I've just added the patch titled
virtio-blk: Call del_gendisk() before disable guest kick
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
virtio-blk-call-del_gendisk-before-disable-guest-kick.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 88963fd6c66bf065c6e9c36f1f5de4dff30624a1 Mon Sep 17 00:00:00 2001
From: Asias He <[email protected]>
Date: Fri, 25 May 2012 10:34:47 +0800
Subject: virtio-blk: Call del_gendisk() before disable guest kick
From: Asias He <[email protected]>
commit 02e2b124943648fba0a2ccee5c3656a5653e0151 upstream.
del_gendisk() might not return due to failing to remove the
/sys/block/vda/serial sysfs entry when another thread (udev) is
trying to read it.
virtblk_remove()
vdev->config->reset() : guest will not kick us through interrupt
del_gendisk()
device_del()
kobject_del(): got stuck, sysfs entry ref count non zero
sysfs_open_file(): user space process read /sys/block/vda/serial
sysfs_get_active() : got sysfs entry ref count
dev_attr_show()
virtblk_serial_show()
blk_execute_rq() : got stuck, interrupt is disabled
request cannot be finished
This patch fixes it by calling del_gendisk() before we disable guest's
interrupt so that the request sent in virtblk_serial_show() will be
finished and del_gendisk() will success.
This fixes another race in hot-unplug process.
It is save to call del_gendisk(vblk->disk) before
flush_work(&vblk->config_work) which might access vblk->disk, because
vblk->disk is not freed until put_disk(vblk->disk).
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Asias He <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
Signed-off-by: Ben Hutchings <[email protected]>
Cc: Yijing Wang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/block/virtio_blk.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -581,13 +581,13 @@ static void __devexit virtblk_remove(str
vblk->config_enable = false;
mutex_unlock(&vblk->config_lock);
+ del_gendisk(vblk->disk);
+
/* Stop all the virtqueues. */
vdev->config->reset(vdev);
flush_work(&vblk->config_work);
- del_gendisk(vblk->disk);
-
/* Abort requests dispatched to driver. */
spin_lock_irqsave(&vblk->lock, flags);
while ((vbr = virtqueue_detach_unused_buf(vblk->vq))) {
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/virtio-blk-fix-hot-unplug-race-in-remove-method.patch
queue-3.4/virtio-blk-call-del_gendisk-before-disable-guest-kick.patch
queue-3.4/virtio_blk-drop-unused-request-tracking-list.patch
queue-3.4/virtio-blk-reset-device-after-blk_cleanup_queue.patch
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