Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1432410 > unrolled thread

[PATCH] virtio-blk: Generate uevent after attribute available

Back to article view | Back to linux.kernel

Contents

  [PATCH] virtio-blk: Generate uevent after attribute available Fam Zheng <famz@redhat.com> - 2016-06-28 04:40 +0200
    Re: [PATCH] virtio-blk: Generate uevent after attribute available Christoph Hellwig <hch@infradead.org> - 2016-06-28 14:40 +0200
      Re: [PATCH] virtio-blk: Generate uevent after attribute available Fam Zheng <famz@redhat.com> - 2016-06-29 03:30 +0200

#1432410 — [PATCH] virtio-blk: Generate uevent after attribute available

Userspace listens to the KOBJ_ADD uevent generated in add_disk. At that
point we haven't created the serial attribute file, therefore depending
on how fast udev reacts, the /dev/disk/by-id/ entry doesn't always get
created.

This race condition can be easily reproduced by hot plugging a number of
virtio-blk disks.

Also in systemd, there used to be a related workaround in udev rules
called 'WAIT_FOR="serial"', but it is removed in later versions.

Now let's generate a KOBJ_CHANGE event after the attributes are ready.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 drivers/block/virtio_blk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 42758b5..5056007 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -567,6 +567,7 @@ static int virtblk_probe(struct virtio_device *vdev)
 {
 	struct virtio_blk *vblk;
 	struct request_queue *q;
+	struct device *ddev;
 	int err, index;
 
 	u64 cap;
@@ -746,6 +747,8 @@ static int virtblk_probe(struct virtio_device *vdev)
 					 &dev_attr_cache_type_ro);
 	if (err)
 		goto out_del_disk;
+	ddev = disk_to_dev(vblk->disk);
+	kobject_uevent(&ddev->kobj, KOBJ_CHANGE);
 	return 0;
 
 out_del_disk:
-- 
2.9.0

[toc] | [next] | [standalone]

#1432958

On Tue, Jun 28, 2016 at 10:39:15AM +0800, Fam Zheng wrote:
> Userspace listens to the KOBJ_ADD uevent generated in add_disk. At that
> point we haven't created the serial attribute file, therefore depending
> on how fast udev reacts, the /dev/disk/by-id/ entry doesn't always get
> created.
> 
> This race condition can be easily reproduced by hot plugging a number of
> virtio-blk disks.
> 
> Also in systemd, there used to be a related workaround in udev rules
> called 'WAIT_FOR="serial"', but it is removed in later versions.
> 
> Now let's generate a KOBJ_CHANGE event after the attributes are ready.

The same race is present in other drivers as well, e.g. nvme.  Please
find a way to make this work properly without needing to hack every
driver to send events manually.

[toc] | [prev] | [next] | [standalone]

#1433395

On Tue, 06/28 04:45, Christoph Hellwig wrote:
> On Tue, Jun 28, 2016 at 10:39:15AM +0800, Fam Zheng wrote:
> > Userspace listens to the KOBJ_ADD uevent generated in add_disk. At that
> > point we haven't created the serial attribute file, therefore depending
> > on how fast udev reacts, the /dev/disk/by-id/ entry doesn't always get
> > created.
> > 
> > This race condition can be easily reproduced by hot plugging a number of
> > virtio-blk disks.
> > 
> > Also in systemd, there used to be a related workaround in udev rules
> > called 'WAIT_FOR="serial"', but it is removed in later versions.
> > 
> > Now let's generate a KOBJ_CHANGE event after the attributes are ready.
> 
> The same race is present in other drivers as well, e.g. nvme.  Please
> find a way to make this work properly without needing to hack every
> driver to send events manually.

OK, I'll take a look today!

Fam

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web