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

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. > > >

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. > > >

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 >

On Wed, Jun 29, 2016 at 09:24:15AM +0800, Fam Zheng wrote: > 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

The race condition is noticed between disk_add() and disk attributes, on virtio-blk hotplug. 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. As pointed out by Christoph Hellwig in the specific fix [1], virtio-blk

The race condition is noticed between disk_add() and disk attributes, on virtio-blk hotplug. 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. As pointed out by Christoph Hellwig in the specific fix [1], virtio-blk

Previously after device_add_disk returns, the KOBJ_ADD uevent is already emitted. Adding attributes after that is a poor usage of kobject, and in practice may result in race conditions with userspace, for example udev checks availability of certain attributes and initializes /dev entries conditionally. device_add_disk can handle adding attribute group better, so use it. Meanwhile, handle error

On Wed, Jun 29, 2016 at 6:59 PM, Fam Zheng <famz at redhat.com> wrote: > It is documented that KOBJ_ADD should be generated after the object's > attributes and children are ready. We can achieve this with the new > disk_gen_uevents interface. > > Signed-off-by: Fam Zheng <famz at redhat.com> > --- > arch/powerpc/sysdev/axonram.c | 3 ++- > 1 file changed,

On Wed, Jun 29, 2016 at 6:59 PM, Fam Zheng <famz at redhat.com> wrote: > It is documented that KOBJ_ADD should be generated after the object's > attributes and children are ready. We can achieve this with the new > disk_gen_uevents interface. > > Signed-off-by: Fam Zheng <famz at redhat.com> > --- > arch/powerpc/sysdev/axonram.c | 3 ++- > 1 file changed,

On Wed, 06/29 23:38, Christoph Hellwig wrote: > On Thu, Jun 30, 2016 at 02:35:54PM +0800, Fam Zheng wrote: > > also more code and less flexible IMO. For example, we need at least two > > variants, for attribute_group and device_attribute separately, right? > > Yes, or maybe just a calling convention that just passes both. OK, I can look into that, but I'm not sure about

On Wed, 06/29 23:38, Christoph Hellwig wrote: > On Thu, Jun 30, 2016 at 02:35:54PM +0800, Fam Zheng wrote: > > also more code and less flexible IMO. For example, we need at least two > > variants, for attribute_group and device_attribute separately, right? > > Yes, or maybe just a calling convention that just passes both. OK, I can look into that, but I'm not sure about

This is an attempt to fix the issue that some disks' sysfs attributes are not ready at the time its KOBJ_ADD event is sent. The symptom is during device hotplug, udev may fail to find certain attributes, such as serial or wwn, of the disk. As a result the /dev/disk/by-id entries are not created. The cause is device_add_disk emits the uevent before returning, and the callers have to create

This is an attempt to fix the issue that some disks' sysfs attributes are not ready at the time its KOBJ_ADD event is sent. The symptom is during device hotplug, udev may fail to find certain attributes, such as serial or wwn, of the disk. As a result the /dev/disk/by-id entries are not created. The cause is device_add_disk emits the uevent before returning, and the callers have to create

When virtio-blk device is resized from host (using block_resize from QEMU) emit KOBJ_CHANGE uevent to notify guest about such change. This allows user to have custom udev rules which would take whatever action if such event occurs. As a proof of concept I've created simple udev rule that automatically resize filesystem on virtio-blk device. ACTION=="change", KERNEL=="vd*",

When virtio-blk device is resized from host (using block_resize from QEMU) emit KOBJ_CHANGE uevent to notify guest about such change. This allows user to have custom udev rules which would take whatever action if such event occurs. As a proof of concept I've created simple udev rule that automatically resize filesystem on virtio-blk device. ACTION=="change", KERNEL=="vd*",

On Tue, Jul 03, 2012 at 03:19:37PM +0200, Paolo Bonzini wrote: > This patch adds support for the new VIRTIO_BLK_F_CONFIG_WCE feature, > which exposes the cache mode in the configuration space and lets the > driver modify it. The cache mode is exposed via sysfs. > > Even if the host does not support the new feature, the cache mode is > visible (thanks to the existing

On Tue, Jul 03, 2012 at 03:19:37PM +0200, Paolo Bonzini wrote: > This patch adds support for the new VIRTIO_BLK_F_CONFIG_WCE feature, > which exposes the cache mode in the configuration space and lets the > driver modify it. The cache mode is exposed via sysfs. > > Even if the host does not support the new feature, the cache mode is > visible (thanks to the existing

On Wed, 06/29 23:24, Christoph Hellwig wrote: > On Thu, Jun 30, 2016 at 09:59:41AM +0800, Fam Zheng wrote: > > Documentation/kobject.txt: > > > Use the KOBJ_ADD action for when the kobject is first added to the kernel. > > > This should be done only after any attributes or children of the kobject > > > have been initialized properly, as userspace will instantly

On Wed, 06/29 23:24, Christoph Hellwig wrote: > On Thu, Jun 30, 2016 at 09:59:41AM +0800, Fam Zheng wrote: > > Documentation/kobject.txt: > > > Use the KOBJ_ADD action for when the kobject is first added to the kernel. > > > This should be done only after any attributes or children of the kobject > > > have been initialized properly, as userspace will instantly

In add_disk(), don't send uevent to userspace when gen_uevent is true; also export the refactored function disk_gen_uevents for later use. Signed-off-by: Fam Zheng <famz at redhat.com> --- block/genhd.c | 23 +++++++++++++++++++---- include/linux/genhd.h | 1 + 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 8e1bfa1..9b66953