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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-01-18 20:17:10 -0500
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-03-14 11:17:09 -0400
commitc7617798771ad588d585986d896197c04b737621 (patch)
tree120b3d73e9e8c808083489770e5324c60e1ce8ec /arch/x86/xen
parentfb38923ead10aa8a28db191548e176e8856614d7 (diff)
xen/mmu: WARN_ON when racing to swap middle leaf.
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 WARN_ON if we do hit this scenario. If we do fail this, it is OK to continue as there is a backup mechanism (VM_IO) that can bypass the P2M and still set the _PAGE_IOMAP flags. [v2: Change from WARN to BUG_ON] [v3: Rebased on top of xen->p2m code split] [v4: Change from BUG_ON to WARN] Reviewed-by: Ian Campbell <Ian.Campbell@eu.citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'arch/x86/xen')
-rw-r--r--arch/x86/xen/p2m.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 809fe3536301..4631cf99e714 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -605,7 +605,8 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
/* Swap over from MISSING to IDENTITY if needed. */
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 true;
}
}