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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 28 Jun 2016 10:39:15 +0800
From:	Fam Zheng <famz@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	virtualization@...ts.linux-foundation.org, famz@...hat.com
Subject: [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@...hat.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