From 2829b449276aed45f3d649efb21e3418e39dd5d1 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Tue, 17 Feb 2009 23:53:19 -0800 Subject: [PATCH] x86/paravirt: allow preemption with lazy mmu mode Impact: remove obsolete checks, simplification Lift restrictions on preemption with lazy mmu mode, as it is now allowed. Signed-off-by: Jeremy Fitzhardinge Acked-by: Peter Zijlstra --- arch/x86/kernel/paravirt.c | 7 ++++--- arch/x86/xen/mmu.c | 8 +------- 2 files changed, 5 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index cf1437503bab..bf2e86eee80c 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -247,7 +247,6 @@ static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LA static inline void enter_lazy(enum paravirt_lazy_mode mode) { BUG_ON(__get_cpu_var(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE); - BUG_ON(preemptible()); __get_cpu_var(paravirt_lazy_mode) = mode; } @@ -255,7 +254,6 @@ static inline void enter_lazy(enum paravirt_lazy_mode mode) static void leave_lazy(enum paravirt_lazy_mode mode) { BUG_ON(__get_cpu_var(paravirt_lazy_mode) != mode); - BUG_ON(preemptible()); __get_cpu_var(paravirt_lazy_mode) = PARAVIRT_LAZY_NONE; } @@ -272,6 +270,8 @@ void paravirt_leave_lazy_mmu(void) void paravirt_start_context_switch(struct task_struct *prev) { + BUG_ON(preemptible()); + if (percpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) { arch_leave_lazy_mmu_mode(); set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES); @@ -281,6 +281,8 @@ void paravirt_start_context_switch(struct task_struct *prev) void paravirt_end_context_switch(struct task_struct *next) { + BUG_ON(preemptible()); + leave_lazy(PARAVIRT_LAZY_CPU); if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES)) @@ -300,7 +302,6 @@ void arch_flush_lazy_mmu_mode(void) preempt_disable(); if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { - WARN_ON(preempt_count() == 1); arch_leave_lazy_mmu_mode(); arch_enter_lazy_mmu_mode(); } diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index f5f8faa4f76c..3f2d0fe5e6a8 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -419,10 +419,6 @@ 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(); - ADD_STATS(set_pte_at, 1); // ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep)); ADD_STATS(set_pte_at_current, mm == current->mm); @@ -443,9 +439,7 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, } xen_set_pte(ptep, pteval); -out: - if (mm == &init_mm) - preempt_enable(); +out: return; } pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, -- GitLab