x86/irq: Avoid memory allocation in __assign_irq_vector()

Function __assign_irq_vector() is protected by vector_lock, so use
a global temporary cpu_mask to avoid allocating/freeing cpu_mask.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: David Cohen <david.a.cohen@linux.intel.com>
Cc: Sander Eikelenboom <linux@eikelenboom.it>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Link: http://lkml.kernel.org/r/1428978610-28986-34-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 17 insertions, 16 deletions

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index ad786f8a7cc7..1c7dd42b98c1 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -30,6 +30,7 @@ struct apic_chip_data {
 
 struct irq_domain *x86_vector_domain;
 static DEFINE_RAW_SPINLOCK(vector_lock);
+static cpumask_var_t vector_cpumask;
 static struct irq_chip lapic_controller;
 #ifdef  CONFIG_X86_IO_APIC
 static struct apic_chip_data *legacy_irq_data[NR_IRQS_LEGACY];
@@ -116,14 +117,10 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
         static int current_vector = FIRST_EXTERNAL_VECTOR + VECTOR_OFFSET_START;
         static int current_offset = VECTOR_OFFSET_START % 16;
         int cpu, err;
-        cpumask_var_t tmp_mask;
 
         if (d->move_in_progress)
                 return -EBUSY;
 
-        if (!alloc_cpumask_var(&tmp_mask, GFP_ATOMIC))
-                return -ENOMEM;
-
         /* Only try and allocate irqs on cpus that are present */
         err = -ENOSPC;
         cpumask_clear(d->old_domain);
@@ -131,21 +128,22 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d,
         while (cpu < nr_cpu_ids) {
                 int new_cpu, vector, offset;
 
-                apic->vector_allocation_domain(cpu, tmp_mask, mask);
+                apic->vector_allocation_domain(cpu, vector_cpumask, mask);
 
-                if (cpumask_subset(tmp_mask, d->domain)) {
+                if (cpumask_subset(vector_cpumask, d->domain)) {
                         err = 0;
-                        if (cpumask_equal(tmp_mask, d->domain))
+                        if (cpumask_equal(vector_cpumask, d->domain))
                                 break;
                         /*
                          * New cpumask using the vector is a proper subset of
                          * the current in use mask. So cleanup the vector
                          * allocation for the members that are not used anymore.
                          */
-                        cpumask_andnot(d->old_domain, d->domain, tmp_mask);
+                        cpumask_andnot(d->old_domain, d->domain,
+                                       vector_cpumask);
                         d->move_in_progress =
                            cpumask_intersects(d->old_domain, cpu_online_mask);
-                        cpumask_and(d->domain, d->domain, tmp_mask);
+                        cpumask_and(d->domain, d->domain, vector_cpumask);
                         break;
                 }
 
@@ -159,16 +157,18 @@ next:
                 }
 
                 if (unlikely(current_vector == vector)) {
-                        cpumask_or(d->old_domain, d->old_domain, tmp_mask);
-                        cpumask_andnot(tmp_mask, mask, d->old_domain);
-                        cpu = cpumask_first_and(tmp_mask, cpu_online_mask);
+                        cpumask_or(d->old_domain, d->old_domain,
+                                   vector_cpumask);
+                        cpumask_andnot(vector_cpumask, mask, d->old_domain);
+                        cpu = cpumask_first_and(vector_cpumask,
+                                                cpu_online_mask);
                         continue;
                 }
 
                 if (test_bit(vector, used_vectors))
                         goto next;
 
-                for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask) {
+                for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask) {
                         if (per_cpu(vector_irq, new_cpu)[vector] >
                             VECTOR_UNDEFINED)
                                 goto next;
@@ -181,14 +181,13 @@ next:
                         d->move_in_progress =
                            cpumask_intersects(d->old_domain, cpu_online_mask);
                 }
-                for_each_cpu_and(new_cpu, tmp_mask, cpu_online_mask)
+                for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask)
                         per_cpu(vector_irq, new_cpu)[vector] = irq;
                 d->cfg.vector = vector;
-                cpumask_copy(d->domain, tmp_mask);
+                cpumask_copy(d->domain, vector_cpumask);
                 err = 0;
                 break;
         }
-        free_cpumask_var(tmp_mask);
 
         if (!err) {
                 /* cache destination APIC IDs into cfg->dest_apicid */
@@ -397,6 +396,8 @@ int __init arch_early_irq_init(void)
         arch_init_msi_domain(x86_vector_domain);
         arch_init_htirq_domain(x86_vector_domain);
 
+        BUG_ON(!alloc_cpumask_var(&vector_cpumask, GFP_KERNEL));
+
         return arch_early_ioapic_init();
 }