[PATCH] kvm: fix crash on irqfd deassign

[PATCH] kvm: fix crash on irqfd deassign

[Michael S. Tsirkin]

irqfd in kvm used flush_work incorrectly:
it assumed that work scheduled previously can't run
after flush_work, but since kvm uses a non-reentrant
workqueue (by means of schedule_work)
we need flush_work_sync to get that guarantee.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
Tested-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
---

Note: this is needed for kernel 2.6.39 and earlier.

 virt/kvm/eventfd.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 2ca4535..cdf51c9 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -90,7 +90,7 @@ irqfd_shutdown(struct work_struct *work)
 	 * We know no new events will be scheduled at this point, so block
 	 * until all previously outstanding events have completed
 	 */
-	flush_work(&irqfd->inject);
+	flush_work_sync(&irqfd->inject);
 
 	/*
 	 * It is now safe to release the object's resources
-- 
1.7.3.2.91.g446ac

Re: [stable] [PATCH] kvm: fix crash on irqfd deassign

[Greg KH]

On Thu, Mar 17, 2011 at 10:53:33AM +0200, Michael S. Tsirkin wrote:
> irqfd in kvm used flush_work incorrectly:
> it assumed that work scheduled previously can't run
> after flush_work, but since kvm uses a non-reentrant
> workqueue (by means of schedule_work)
> we need flush_work_sync to get that guarantee.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reported-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
> Tested-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
> ---
> 
> Note: this is needed for kernel 2.6.39 and earlier.

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
for how to do this properly.

thanks,

greg k-h

Re: [stable] [PATCH] kvm: fix crash on irqfd deassign

[Michael S. Tsirkin]

On Thu, Mar 17, 2011 at 09:13:08AM -0700, Greg KH wrote:
> On Thu, Mar 17, 2011 at 10:53:33AM +0200, Michael S. Tsirkin wrote:
> > irqfd in kvm used flush_work incorrectly:
> > it assumed that work scheduled previously can't run
> > after flush_work, but since kvm uses a non-reentrant
> > workqueue (by means of schedule_work)
> > we need flush_work_sync to get that guarantee.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > Reported-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
> > Tested-by: Jean-Philippe Menil <jean-philippe.menil@univ-nantes.fr>
> > ---
> > 
> > Note: this is needed for kernel 2.6.39 and earlier.
> 
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree.  Please read Documentation/stable_kernel_rules.txt
> for how to do this properly.
> 
> thanks,
> 
> greg k-h

What I missed is Cc: stable@kernel.org in the text?
OK, thanks for the correction.  Actually I forgot, Avi and Marcelo want
to handle stable patches for kvm themselves.
Avi, Marcelo, right?
So Greg, you can forget about this one for now.

Thanks,

-- 
MST

Re: [PATCH] kvm: fix crash on irqfd deassign

[Avi Kivity]

On 03/17/2011 10:53 AM, Michael S. Tsirkin wrote:
> irqfd in kvm used flush_work incorrectly:
> it assumed that work scheduled previously can't run
> after flush_work, but since kvm uses a non-reentrant
> workqueue (by means of schedule_work)
> we need flush_work_sync to get that guarantee.
>
> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> Reported-by: Jean-Philippe Menil<jean-philippe.menil@univ-nantes.fr>
> Tested-by: Jean-Philippe Menil<jean-philippe.menil@univ-nantes.fr>
> ---
>
> Note: this is needed for kernel 2.6.39 and earlier.
>

What about kvm.git master?

-- 
error compiling committee.c: too many arguments to function

Re: [PATCH] kvm: fix crash on irqfd deassign

[Michael S. Tsirkin]

On Tue, Mar 22, 2011 at 02:37:27PM +0200, Avi Kivity wrote:
> On 03/17/2011 10:53 AM, Michael S. Tsirkin wrote:
> >irqfd in kvm used flush_work incorrectly:
> >it assumed that work scheduled previously can't run
> >after flush_work, but since kvm uses a non-reentrant
> >workqueue (by means of schedule_work)
> >we need flush_work_sync to get that guarantee.
> >
> >Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> >Reported-by: Jean-Philippe Menil<jean-philippe.menil@univ-nantes.fr>
> >Tested-by: Jean-Philippe Menil<jean-philippe.menil@univ-nantes.fr>
> >---
> >
> >Note: this is needed for kernel 2.6.39 and earlier.
> >
> 
> What about kvm.git master?

Sorry about the confusion.

Clarification: this is needed on  kvm.git master,
as well as 2.6.39 and earlier.

> -- 
> error compiling committee.c: too many arguments to function

Re: [PATCH] kvm: fix crash on irqfd deassign

[Avi Kivity]

On 03/17/2011 10:53 AM, Michael S. Tsirkin wrote:
> irqfd in kvm used flush_work incorrectly:
> it assumed that work scheduled previously can't run
> after flush_work, but since kvm uses a non-reentrant
> workqueue (by means of schedule_work)
> we need flush_work_sync to get that guarantee.
>

Applied, and queued for 2.6.39.  Thanks.

-- 
error compiling committee.c: too many arguments to function