From mboxrd@z Thu Jan 1 00:00:00 1970 From: srivatsa.bhat@linux.vnet.ibm.com (Srivatsa S. Bhat) Date: Tue, 22 Jan 2013 13:10:51 +0530 Subject: [PATCH v5 29/45] x86/xen: Use get/put_online_cpus_atomic() to prevent CPU offline In-Reply-To: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> References: <20130122073210.13822.50434.stgit@srivatsabhat.in.ibm.com> Message-ID: <20130122074046.13822.61950.stgit@srivatsabhat.in.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Once stop_machine() is gone from the CPU offline path, we won't be able to depend on preempt_disable() or local_irq_disable() to prevent CPUs from going offline from under us. Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline, while invoking from atomic context. Cc: Konrad Rzeszutek Wilk Cc: Jeremy Fitzhardinge Cc: "H. Peter Anvin" Cc: x86 at kernel.org Cc: xen-devel at lists.xensource.com Cc: virtualization at lists.linux-foundation.org Signed-off-by: Srivatsa S. Bhat --- arch/x86/xen/mmu.c | 11 +++++++++-- arch/x86/xen/smp.c | 9 +++++++++ 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 01de35c..6a95a15 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -39,6 +39,7 @@ * Jeremy Fitzhardinge , XenSource Inc, 2007 */ #include +#include #include #include #include @@ -1163,9 +1164,13 @@ static void xen_drop_mm_ref(struct mm_struct *mm) */ static void xen_exit_mmap(struct mm_struct *mm) { - get_cpu(); /* make sure we don't move around */ + /* + * Make sure we don't move around, and prevent CPUs from going + * offline. + */ + get_online_cpus_atomic(); xen_drop_mm_ref(mm); - put_cpu(); + put_online_cpus_atomic(); spin_lock(&mm->page_table_lock); @@ -1371,6 +1376,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus, args->op.arg2.vcpumask = to_cpumask(args->mask); /* Remove us, and any offline CPUS. */ + get_online_cpus_atomic(); cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask)); @@ -1383,6 +1389,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus, MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF); xen_mc_issue(PARAVIRT_LAZY_MMU); + put_online_cpus_atomic(); } static unsigned long xen_read_cr3(void) diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index 4f7d259..7d753ae 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -487,8 +488,10 @@ static void __xen_send_IPI_mask(const struct cpumask *mask, { unsigned cpu; + get_online_cpus_atomic(); for_each_cpu_and(cpu, mask, cpu_online_mask) xen_send_IPI_one(cpu, vector); + put_online_cpus_atomic(); } static void xen_smp_send_call_function_ipi(const struct cpumask *mask) @@ -551,8 +554,10 @@ void xen_send_IPI_all(int vector) { int xen_vector = xen_map_vector(vector); + get_online_cpus_atomic(); if (xen_vector >= 0) __xen_send_IPI_mask(cpu_online_mask, xen_vector); + put_online_cpus_atomic(); } void xen_send_IPI_self(int vector) @@ -572,20 +577,24 @@ void xen_send_IPI_mask_allbutself(const struct cpumask *mask, if (!(num_online_cpus() > 1)) return; + get_online_cpus_atomic(); for_each_cpu_and(cpu, mask, cpu_online_mask) { if (this_cpu == cpu) continue; xen_smp_send_call_function_single_ipi(cpu); } + put_online_cpus_atomic(); } void xen_send_IPI_allbutself(int vector) { int xen_vector = xen_map_vector(vector); + get_online_cpus_atomic(); if (xen_vector >= 0) xen_send_IPI_mask_allbutself(cpu_online_mask, xen_vector); + put_online_cpus_atomic(); } static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)