From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 17 Jun 2009 13:53:47 +0000 (-0300)
Subject: KVM: protect concurrent make_all_cpus_request
X-Git-Tag: v2.6.31-rc2~73^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84261923d3dddb766736023bead6fa07b7e218d5;p=pandora-kernel.git

KVM: protect concurrent make_all_cpus_request

make_all_cpus_request contains a race condition which can
trigger false request completed status, as follows:

CPU0                                              CPU1

if (test_and_set_bit(req,&vcpu->requests))
   ....                                        	   if (test_and_set_bit(req,&vcpu->requests))
   ..                                                  return
proceed to smp_call_function_many(wait=1)

Use a spinlock to serialize concurrent CPUs.

Cc: stable@kernel.org
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---

Reading git-diff-tree failed