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Subject[PATCH] x86/x2apic: don't use before alloc in x2apic_cluster_probe()
Date
I made a mistake while converting the driver to the hotplug state
machine and as a result x2apic_cluster_probe() was accessing
cpus_in_cluster before allocating it.
This patch fixes it by setting the cpumask after the allocation the
memory succeeded.
While at it, I marked two functions static which are only used within
this file.

Reported-by: Laura Abbott <labbott@redhat.com>
Fixes: 6b2c28471de5 ("x86/x2apic: Convert to CPU hotplug state machine")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/apic/x2apic_cluster.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index 6368fa69d2af..54f35d988025 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -155,7 +155,7 @@ static void init_x2apic_ldr(void)
/*
* At CPU state changes, update the x2apic cluster sibling info.
*/
-int x2apic_prepare_cpu(unsigned int cpu)
+static int x2apic_prepare_cpu(unsigned int cpu)
{
if (!zalloc_cpumask_var(&per_cpu(cpus_in_cluster, cpu), GFP_KERNEL))
return -ENOMEM;
@@ -168,7 +168,7 @@ int x2apic_prepare_cpu(unsigned int cpu)
return 0;
}

-int x2apic_dead_cpu(unsigned int this_cpu)
+static int x2apic_dead_cpu(unsigned int this_cpu)
{
int cpu;

@@ -186,13 +186,18 @@ int x2apic_dead_cpu(unsigned int this_cpu)
static int x2apic_cluster_probe(void)
{
int cpu = smp_processor_id();
+ int ret;

if (!x2apic_mode)
return 0;

+ ret = cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "X2APIC_PREPARE",
+ x2apic_prepare_cpu, x2apic_dead_cpu);
+ if (ret < 0) {
+ pr_err("Failed to register X2APIC_PREPARE\n");
+ return 0;
+ }
cpumask_set_cpu(cpu, per_cpu(cpus_in_cluster, cpu));
- cpuhp_setup_state(CPUHP_X2APIC_PREPARE, "X2APIC_PREPARE",
- x2apic_prepare_cpu, x2apic_dead_cpu);
return 1;
}

--
2.8.1
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