From: Jeremy Fitzhardinge Date: Wed, 2 Apr 2008 17:54:10 +0000 (-0700) Subject: xen: allow set_pte_at on init_mm to be lockless X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2bd50036b5dfc929390ddc48be7f6314447b2be3;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git 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 Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 272635aaef88..6cbcf65609ad 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)