Re: [PATCH] kvm: make processes waiting on vcpu mutex killable

[Marcelo Tosatti <mtosatti@redhat.com>]

On Sun, Sep 16, 2012 at 11:50:30AM +0300, Michael S. Tsirkin wrote:
> vcpu mutex can be held for unlimited time so
> taking it with mutex_lock on an ioctl is wrong:
> one process could be passed a vcpu fd and
> call this ioctl on the vcpu used by another process,
> it will then be unkillable until the owner exits.
> 
> Call mutex_lock_killable instead and return status.
> Note: mutex_lock_interruptible would be even nicer,
> but I am not sure all users are prepared to handle EINTR
> from these ioctls. They might misinterpret it as an error.
> 
> Cleanup paths expect a vcpu that can't be used by
> any userspace so this will always succeed - catch bugs
> by calling BUG_ON.
> 
> Catch callers that don't check return state by adding
> __must_check.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> 
> It's a minor bugfix - should we put it in 3.6?

Applied to branch 'queue' on the basis its not a regression/critical problem,
thanks.