4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> commit 3716fd27a604d61a91cda47083504971486b80f1 upstream. __assign_irq_vector() uses the vector_cpumask which is assigned by apic->vector_allocation_domain() without doing basic sanity checks. That can result in a situation where the final assignement of a newly found vector fails in apic->cpu_mask_to_apicid_and(). So we have to do rollbacks for no reason. apic->cpu_mask_to_apicid_and() only fails if vector_cpumask & requested_cpumask & cpu_online_mask is empty. Check for this condition right away and if the result is empty try immediately the next possible cpu in the requested mask. So in case of a failure the old setting is unchanged and we can remove the rollback code. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Tested-by: Borislav Petkov <bp@xxxxxxxxx> Tested-by: Joe Lawrence <joe.lawrence@xxxxxxxxxxx> Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> Cc: Jeremiah Mahler <jmmahler@xxxxxxxxx> Cc: andy.shevchenko@xxxxxxxxx Cc: Guenter Roeck <linux@xxxxxxxxxxxx> Link: http://lkml.kernel.org/r/20151231160106.561877324@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/apic/vector.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -30,7 +30,7 @@ struct apic_chip_data { struct irq_domain *x86_vector_domain; static DEFINE_RAW_SPINLOCK(vector_lock); -static cpumask_var_t vector_cpumask, searched_cpumask; +static cpumask_var_t vector_cpumask, vector_searchmask, searched_cpumask; static struct irq_chip lapic_controller; #ifdef CONFIG_X86_IO_APIC static struct apic_chip_data *legacy_irq_data[NR_IRQS_LEGACY]; @@ -128,8 +128,20 @@ static int __assign_irq_vector(int irq, while (cpu < nr_cpu_ids) { int new_cpu, vector, offset; + /* Get the possible target cpus for @mask/@cpu from the apic */ apic->vector_allocation_domain(cpu, vector_cpumask, mask); + /* + * Clear the offline cpus from @vector_cpumask for searching + * and verify whether the result overlaps with @mask. If true, + * then the call to apic->cpu_mask_to_apicid_and() will + * succeed as well. If not, no point in trying to find a + * vector in this mask. + */ + cpumask_and(vector_searchmask, vector_cpumask, cpu_online_mask); + if (!cpumask_intersects(vector_searchmask, mask)) + goto next_cpu; + if (cpumask_subset(vector_cpumask, d->domain)) { if (cpumask_equal(vector_cpumask, d->domain)) goto success; @@ -162,7 +174,7 @@ next: if (test_bit(vector, used_vectors)) goto next; - for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask) { + for_each_cpu(new_cpu, vector_searchmask) { if (!IS_ERR_OR_NULL(per_cpu(vector_irq, new_cpu)[vector])) goto next; } @@ -174,7 +186,7 @@ next: d->move_in_progress = cpumask_intersects(d->old_domain, cpu_online_mask); } - for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask) + for_each_cpu(new_cpu, vector_searchmask) per_cpu(vector_irq, new_cpu)[vector] = irq_to_desc(irq); d->cfg.vector = vector; cpumask_copy(d->domain, vector_cpumask); @@ -196,8 +208,14 @@ next_cpu: return -ENOSPC; success: - /* cache destination APIC IDs into cfg->dest_apicid */ - return apic->cpu_mask_to_apicid_and(mask, d->domain, &d->cfg.dest_apicid); + /* + * Cache destination APIC IDs into cfg->dest_apicid. This cannot fail + * as we already established, that mask & d->domain & cpu_online_mask + * is not empty. + */ + BUG_ON(apic->cpu_mask_to_apicid_and(mask, d->domain, + &d->cfg.dest_apicid)); + return 0; } static int assign_irq_vector(int irq, struct apic_chip_data *data, @@ -407,6 +425,7 @@ int __init arch_early_irq_init(void) arch_init_htirq_domain(x86_vector_domain); BUG_ON(!alloc_cpumask_var(&vector_cpumask, GFP_KERNEL)); + BUG_ON(!alloc_cpumask_var(&vector_searchmask, GFP_KERNEL)); BUG_ON(!alloc_cpumask_var(&searched_cpumask, GFP_KERNEL)); return arch_early_ioapic_init(); @@ -496,14 +515,7 @@ static int apic_set_affinity(struct irq_ return -EINVAL; err = assign_irq_vector(irq, data, dest); - if (err) { - if (assign_irq_vector(irq, data, - irq_data_get_affinity_mask(irq_data))) - pr_err("Failed to recover vector for irq %d\n", irq); - return err; - } - - return IRQ_SET_MASK_OK; + return err ? err : IRQ_SET_MASK_OK; } static struct irq_chip lapic_controller = { -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html