[PATCH] x86, cpu hotplug, use cpumask stack safe variant cpumask_var_t in check_irq_vectors_for_cpu_disable() [v2]

From: Prarit Bhargava
Date: Mon Jan 20 2014 - 13:58:18 EST


kbuild, 0day kernel build service, outputs the warning:

arch/x86/kernel/irq.c:333:1: warning: the frame size of 2056 bytes
is larger than 2048 bytes [-Wframe-larger-than=]

because check_irq_vectors_for_cpu_disable() allocates two cpumasks on the
stack. Fix this by using cpumask_var_t, the cpumask stack safe variant.

Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Seiji Aguchi <seiji.aguchi@xxxxxxx>
Cc: Yang Zhang <yang.z.zhang@xxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Janet Morgan <janet.morgan@xxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Ruiv Wang <ruiv.wang@xxxxxxxxx>
Cc: Gong Chen <gong.chen@xxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: Gong Chen <gong.chen@xxxxxxxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>

[v2]: switch from GFP_KERNEL to GFP_ATOMIC
---
arch/x86/kernel/irq.c | 35 +++++++++++++++++++++++++----------
1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 4207e8d..c130cfa 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -269,15 +269,25 @@ EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
*/
int check_irq_vectors_for_cpu_disable(void)
{
- int irq, cpu;
+ int irq, cpu, ret = 0;
unsigned int this_cpu, vector, this_count, count;
struct irq_desc *desc;
struct irq_data *data;
- struct cpumask affinity_new, online_new;
+ cpumask_var_t affinity_new, online_new;
+
+ if (!alloc_cpumask_var(&online_new, GFP_ATOMIC)){
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ if (!alloc_cpumask_var(&affinity_new, GFP_ATOMIC)) {
+ ret = -ENOMEM;
+ goto free_online_new;
+ }

this_cpu = smp_processor_id();
- cpumask_copy(&online_new, cpu_online_mask);
- cpu_clear(this_cpu, online_new);
+ cpumask_copy(online_new, cpu_online_mask);
+ __cpu_clear(this_cpu, online_new);

this_count = 0;
for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
@@ -285,8 +295,8 @@ int check_irq_vectors_for_cpu_disable(void)
if (irq >= 0) {
desc = irq_to_desc(irq);
data = irq_desc_get_irq_data(desc);
- cpumask_copy(&affinity_new, data->affinity);
- cpu_clear(this_cpu, affinity_new);
+ cpumask_copy(affinity_new, data->affinity);
+ __cpu_clear(this_cpu, affinity_new);

/* Do not count inactive or per-cpu irqs. */
if (!irq_has_action(irq) || irqd_is_per_cpu(data))
@@ -307,8 +317,8 @@ int check_irq_vectors_for_cpu_disable(void)
* mask is not zero; that is the down'd cpu is the
* last online cpu in a user set affinity mask.
*/
- if (cpumask_empty(&affinity_new) ||
- !cpumask_subset(&affinity_new, &online_new))
+ if (cpumask_empty(affinity_new) ||
+ !cpumask_subset(affinity_new, online_new))
this_count++;
}
}
@@ -327,9 +337,14 @@ int check_irq_vectors_for_cpu_disable(void)
if (count < this_count) {
pr_warn("CPU %d disable failed: CPU has %u vectors assigned and there are only %u available.\n",
this_cpu, this_count, count);
- return -ERANGE;
+ ret = -ERANGE;
}
- return 0;
+
+ free_cpumask_var(affinity_new);
+free_online_new:
+ free_cpumask_var(online_new);
+out:
+ return ret;
}

/* A cpu has been removed from cpu_online_mask. Reset irq affinities. */
--
1.7.9.3

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