| Message ID | 20130122074046.13822.61950.stgit@srivatsabhat.in.ibm.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, Jan 22, 2013 at 01:10:51PM +0530, Srivatsa S. Bhat wrote: > 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 <konrad.wilk@oracle.com> Weird. I see this in the patch but I don't see it in the header? Did you explicitly suppress the CC part? Anyhow, the patch looks sane enough, thought I need to to run it through a test framework just to be on a sure side. > Cc: Jeremy Fitzhardinge <jeremy@goop.org> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: x86@kernel.org > Cc: xen-devel@lists.xensource.com > Cc: virtualization@lists.linux-foundation.org > Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> > --- > > 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 <jeremy@xensource.com>, XenSource Inc, 2007 > */ > #include <linux/sched.h> > +#include <linux/cpu.h> > #include <linux/highmem.h> > #include <linux/debugfs.h> > #include <linux/bug.h> > @@ -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 <linux/err.h> > #include <linux/slab.h> > #include <linux/smp.h> > +#include <linux/cpu.h> > #include <linux/irq_work.h> > > #include <asm/paravirt.h> > @@ -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) > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
On 02/19/2013 11:40 PM, Konrad Rzeszutek Wilk wrote: > On Tue, Jan 22, 2013 at 01:10:51PM +0530, Srivatsa S. Bhat wrote: >> 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 <konrad.wilk@oracle.com> > > Weird. I see this in the patch but I don't see it in the header? Meaning, you didn't get this email at all? > Did you > explicitly suppress the CC part? > No.. I sent the entire patchset to a set of email ids and in addition to that I CC'ed individual patches to the respective maintainers/lists (the CC: list in the changelog). I used the --auto knob from stgit to do that. > > Anyhow, the patch looks sane enough, thought I need to to run it through > a test framework just to be on a sure side. > Sure, thank you. But you might want to test the v6 that I sent out yesterday instead of v5. Oh, wait a min, you didn't get the v6 mail also? Here it is, for your reference: http://marc.info/?l=linux-kernel&m=136119260122255&w=2 Regards, Srivatsa S. Bhat >> Cc: Jeremy Fitzhardinge <jeremy@goop.org> >> Cc: "H. Peter Anvin" <hpa@zytor.com> >> Cc: x86@kernel.org >> Cc: xen-devel@lists.xensource.com >> Cc: virtualization@lists.linux-foundation.org >> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> >> ---
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 <jeremy@xensource.com>, XenSource Inc, 2007 */ #include <linux/sched.h> +#include <linux/cpu.h> #include <linux/highmem.h> #include <linux/debugfs.h> #include <linux/bug.h> @@ -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 <linux/err.h> #include <linux/slab.h> #include <linux/smp.h> +#include <linux/cpu.h> #include <linux/irq_work.h> #include <asm/paravirt.h> @@ -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)
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 <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: x86@kernel.org Cc: xen-devel@lists.xensource.com Cc: virtualization@lists.linux-foundation.org Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> --- arch/x86/xen/mmu.c | 11 +++++++++-- arch/x86/xen/smp.c | 9 +++++++++ 2 files changed, 18 insertions(+), 2 deletions(-)