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Subject[Patch Part2 v5 33/33] x86/irq: Avoid memory allocation in __assign_irq_vector()
Date
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>
---
arch/x86/kernel/apic/vector.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index f5eb3999383f..4a04b25cdcdf 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();
}

--
1.7.10.4


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