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Message-ID: <20120518102659.GC31517@dhcp-26-207.brq.redhat.com>
Date: Fri, 18 May 2012 12:26:59 +0200
From: Alexander Gordeev <agordeev@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: x86@...nel.org, Suresh Siddha <suresh.b.siddha@...el.com>,
Cyrill Gorcunov <gorcunov@...nvz.org>,
Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 3/3][RFC] x86: x2apic/cluster: Do not handle cpumask
allocation errors
With this fix allocations of cpumasks are assumed always successfull
and possible failures result in BUG(). It allows few improvements:
- the code that selects destination CPUs from a cpumask is cleaned
and always returns the best possible subset of processors;
- 'ipi_mask' per-cpu variable is eliminated;
- copying of cpumask with local interrupts disabled is avoided;
Signed-off-by: Alexander Gordeev <agordeev@...hat.com>
---
arch/x86/kernel/apic/x2apic_cluster.c | 107 ++++++++-------------------------
1 files changed, 26 insertions(+), 81 deletions(-)
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index f8fa4c4..e5770cd 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -12,7 +12,6 @@
static DEFINE_PER_CPU(u32, x86_cpu_to_logical_apicid);
static DEFINE_PER_CPU(cpumask_var_t, cpus_in_cluster);
-static DEFINE_PER_CPU(cpumask_var_t, ipi_mask);
static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
{
@@ -28,35 +27,32 @@ static void
__x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
{
struct cpumask *cpus_in_cluster_ptr;
- struct cpumask *ipi_mask_ptr;
unsigned int cpu, this_cpu;
unsigned long flags;
u32 dest;
+ cpumask_var_t tmp_mask;
- x2apic_wrmsr_fence();
-
- local_irq_save(flags);
+ if (unlikely(!alloc_cpumask_var(&tmp_mask, GFP_ATOMIC)))
+ BUG();
+ cpumask_copy(tmp_mask, mask);
this_cpu = smp_processor_id();
- /*
- * We are to modify mask, so we need an own copy
- * and be sure it's manipulated with irq off.
- */
- ipi_mask_ptr = __raw_get_cpu_var(ipi_mask);
- cpumask_copy(ipi_mask_ptr, mask);
+ x2apic_wrmsr_fence();
+
+ local_irq_save(flags);
/*
* The idea is to send one IPI per cluster.
*/
- for_each_cpu(cpu, ipi_mask_ptr) {
+ for_each_cpu(cpu, tmp_mask) {
unsigned long i;
cpus_in_cluster_ptr = per_cpu(cpus_in_cluster, cpu);
dest = 0;
/* Collect cpus in cluster. */
- for_each_cpu_and(i, ipi_mask_ptr, cpus_in_cluster_ptr) {
+ for_each_cpu_and(i, tmp_mask, cpus_in_cluster_ptr) {
if (apic_dest == APIC_DEST_ALLINC || i != this_cpu)
dest |= per_cpu(x86_cpu_to_logical_apicid, i);
}
@@ -69,10 +65,12 @@ __x2apic_send_IPI_mask(const struct cpumask *mask, int vector, int apic_dest)
* Cluster sibling cpus should be discared now so
* we would not send IPI them second time.
*/
- cpumask_andnot(ipi_mask_ptr, ipi_mask_ptr, cpus_in_cluster_ptr);
+ cpumask_andnot(tmp_mask, tmp_mask, cpus_in_cluster_ptr);
}
local_irq_restore(flags);
+
+ free_cpumask_var(tmp_mask);
}
static void x2apic_send_IPI_mask(const struct cpumask *mask, int vector)
@@ -116,14 +114,10 @@ __x2apic_cpu_mask_to_apicid(const struct cpumask *cpumask, unsigned int *apicid)
unsigned int weight, max_weight;
cpumask_var_t target_cpus, cluster_cpus;
- if (unlikely(!alloc_cpumask_var(&target_cpus, GFP_ATOMIC))) {
- ret = -ENOMEM;
- goto out;
- }
- if (unlikely(!alloc_cpumask_var(&cluster_cpus, GFP_ATOMIC))) {
- ret = -ENOMEM;
- goto out_free_target_cpus;
- }
+ if (unlikely(!alloc_cpumask_var(&target_cpus, GFP_ATOMIC)))
+ BUG();
+ if (unlikely(!alloc_cpumask_var(&cluster_cpus, GFP_ATOMIC)))
+ BUG();
cpumask_and(target_cpus, cpumask, cpu_online_mask);
max_weight = 0;
@@ -149,34 +143,20 @@ __x2apic_cpu_mask_to_apicid(const struct cpumask *cpumask, unsigned int *apicid)
out_free_cluster_cpus:
free_cpumask_var(cluster_cpus);
-out_free_target_cpus:
free_cpumask_var(target_cpus);
-out:
+
return ret;
}
static unsigned int x2apic_cpu_mask_to_apicid(const struct cpumask *cpumask)
{
int err;
- int cpu;
- unsigned int apicid;
+ unsigned int apicid = BAD_APICID;
err = __x2apic_cpu_mask_to_apicid(cpumask, &apicid);
WARN_ON(err);
- if (!err)
- return apicid;
-
- if (err == -ENOMEM) {
- for_each_cpu(cpu, cpumask) {
- if (cpumask_test_cpu(cpu, cpu_online_mask))
- break;
- }
- if (cpu < nr_cpu_ids)
- return __x2apic_cluster_to_apicid(cpu, cpumask);
- }
-
- return BAD_APICID;
+ return apicid;
}
static unsigned int
@@ -184,46 +164,17 @@ x2apic_cpu_mask_to_apicid_and(const struct cpumask *cpumask,
const struct cpumask *andmask)
{
int err;
- int cpu, first_cpu;
- unsigned int apicid;
+ unsigned int apicid = 0;
cpumask_var_t target_cpus;
- if (likely(alloc_cpumask_var(&target_cpus, GFP_ATOMIC))) {
- cpumask_and(target_cpus, cpumask, andmask);
-
- err = __x2apic_cpu_mask_to_apicid(target_cpus, &apicid);
-
- free_cpumask_var(target_cpus);
-
- if (!err)
- return apicid;
- } else {
- err = -ENOMEM;
- }
+ if (unlikely(!alloc_cpumask_var(&target_cpus, GFP_ATOMIC)))
+ BUG();
+ cpumask_and(target_cpus, cpumask, andmask);
+ err = __x2apic_cpu_mask_to_apicid(target_cpus, &apicid);
WARN_ON(err);
- if (err != -ENOMEM)
- return 0;
-
- apicid = 0;
- first_cpu = nr_cpu_ids;
-
- for_each_cpu_and(cpu, cpumask, andmask) {
- if (cpumask_test_cpu(cpu, cpu_online_mask)) {
- first_cpu = cpu;
- break;
- }
- }
-
- if (first_cpu < nr_cpu_ids) {
- for_each_cpu_and(cpu, per_cpu(cpus_in_cluster, first_cpu),
- cpumask) {
- if (!cpumask_test_cpu(cpu, andmask))
- continue;
- apicid |= per_cpu(x86_cpu_to_logical_apicid, cpu);
- }
- }
+ free_cpumask_var(target_cpus);
return apicid;
}
@@ -265,10 +216,6 @@ update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu)
if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, this_cpu),
GFP_KERNEL)) {
err = -ENOMEM;
- } else if (!zalloc_cpumask_var(&per_cpu(ipi_mask, this_cpu),
- GFP_KERNEL)) {
- free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
- err = -ENOMEM;
}
break;
case CPU_UP_CANCELED:
@@ -281,7 +228,6 @@ update_clusterinfo(struct notifier_block *nfb, unsigned long action, void *hcpu)
__cpu_clear(cpu, per_cpu(cpus_in_cluster, this_cpu));
}
free_cpumask_var(per_cpu(cpus_in_cluster, this_cpu));
- free_cpumask_var(per_cpu(ipi_mask, this_cpu));
break;
}
@@ -297,9 +243,8 @@ static int x2apic_init_cpu_notifier(void)
int cpu = smp_processor_id();
zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL);
- zalloc_cpumask_var(&per_cpu(ipi_mask, cpu), GFP_KERNEL);
- BUG_ON(!per_cpu(cpus_in_cluster, cpu) || !per_cpu(ipi_mask, cpu));
+ BUG_ON(!per_cpu(cpus_in_cluster, cpu));
__cpu_set(cpu, per_cpu(cpus_in_cluster, cpu));
register_hotcpu_notifier(&x2apic_cpu_notifier);
--
1.7.6.5
--
Regards,
Alexander Gordeev
agordeev@...hat.com
--
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