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authorJeremy Fitzhardinge <jeremy@goop.org>2008-04-02 10:54:10 -0700
committerIngo Molnar <mingo@elte.hu>2008-04-24 23:57:33 +0200
commit2bd50036b5dfc929390ddc48be7f6314447b2be3 (patch)
tree638901ec17236c692273ce18e9160e7d29264a26 /arch/x86
parent41e332b2a2dfe514cd441ed0ce1096ed1863e378 (diff)
xen: allow set_pte_at on init_mm to be lockless
The usual pagetable locking protocol doesn't seem to apply to updates to init_mm, so don't rely on preemption being disabled in xen_set_pte_at on init_mm. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/xen/mmu.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 272635aaef8..6cbcf65609a 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -156,6 +156,10 @@ void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags)
void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pteval)
{
+ /* updates to init_mm may be done without lock */
+ if (mm == &init_mm)
+ preempt_disable();
+
if (mm == current->mm || mm == &init_mm) {
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
struct multicall_space mcs;
@@ -163,12 +167,16 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
MULTI_update_va_mapping(mcs.mc, addr, pteval, 0);
xen_mc_issue(PARAVIRT_LAZY_MMU);
- return;
+ goto out;
} else
if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0)
- return;
+ goto out;
}
xen_set_pte(ptep, pteval);
+
+out:
+ if (mm == &init_mm)
+ preempt_enable();
}
pteval_t xen_pte_val(pte_t pte)