From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: [PATCH 4/8] xen/mmu: Warn against races. Date: Thu, 30 Dec 2010 14:48:33 -0500 Message-ID: <1293738517-7287-5-git-send-email-konrad.wilk@oracle.com> References: <1293738517-7287-1-git-send-email-konrad.wilk@oracle.com> Return-path: In-Reply-To: <1293738517-7287-1-git-send-email-konrad.wilk@oracle.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, Jeremy Fitzhardinge , hpa@zytor.com, Ian Campbell Cc: Jan Beulich , xen-devel@lists.xensource.com, Konrad Rzeszutek Wilk , Stefano Stabellini , Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org The initial bootup code uses set_phys_to_machine quite a lot, and after bootup it would be used by the balloon driver. The balloon driver does have mutex lock so this should not be necessary - but just in case, add a warning if we do hit this scenario. Signed-off-by: Konrad Rzeszutek Wilk --- arch/x86/xen/mmu.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 667901f..36bdd2d 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -553,11 +553,13 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) /* Swap over from MISSING to IDENTITY if needed. */ if (p2m_top[topidx] == p2m_mid_missing) { - p2m_top[topidx] = p2m_mid_identity; + WARN_ON(cmpxchg(&p2m_top[topidx], p2m_mid_missing, + p2m_mid_identity) != p2m_mid_missing); return 1; } if (p2m_top[topidx][mididx] == p2m_missing) { - p2m_top[topidx][mididx] = p2m_identity; + WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing, + p2m_identity) != p2m_missing); return 1; } } -- 1.7.1