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Subject[PATCH 1/1] x86: Add check for node passed to node_to_cpumask
Subject: [PATCH 1/1] x86: Add check for node passed to node_to_cpumask

* When CONFIG_DEBUG_PER_CPU_MAPS is set, the node passed to
node_to_cpumask and node_to_cpumask_ptr should be validated.

Based on "Thu Jun 26 09:23:55 PDT 2008" tip/master... ;-)

Signed-off-by: Mike Travis <travis@sgi.com>
---
arch/x86/kernel/setup.c | 26 +++++++++++++++++++++++---
include/asm-x86/topology.h | 7 ++++++-
2 files changed, 29 insertions(+), 4 deletions(-)

--- linux-2.6.tip.orig/arch/x86/kernel/setup.c
+++ linux-2.6.tip/arch/x86/kernel/setup.c
@@ -377,6 +377,10 @@ int early_cpu_to_node(int cpu)
return per_cpu(x86_cpu_to_node_map, cpu);
}

+
+/* empty cpumask */
+static const cpumask_t cpu_mask_none;
+
/*
* Returns a pointer to the bitmask of CPUs on Node 'node'.
*/
@@ -389,13 +393,23 @@ cpumask_t *_node_to_cpumask_ptr(int node
dump_stack();
return &cpu_online_map;
}
- BUG_ON(node >= nr_node_ids);
- return &node_to_cpumask_map[node];
+ if (node >= nr_node_ids) {
+ printk(KERN_WARNING
+ "_node_to_cpumask_ptr(%d): node > nr_node_ids(%d)\n",
+ node, nr_node_ids);
+ dump_stack();
+ return &cpu_mask_none;
+ }
+ return (cpumask_t *)&node_to_cpumask_map[node];
}
EXPORT_SYMBOL(_node_to_cpumask_ptr);

/*
* Returns a bitmask of CPUs on Node 'node'.
+ *
+ * Side note: this function creates the returned cpumask on the stack
+ * so with a high NR_CPUS count, excessive stack space is used. The
+ * node_to_cpumask_ptr function should be used whenever possible.
*/
cpumask_t node_to_cpumask(int node)
{
@@ -405,7 +419,13 @@ cpumask_t node_to_cpumask(int node)
dump_stack();
return cpu_online_map;
}
- BUG_ON(node >= nr_node_ids);
+ if (node >= nr_node_ids) {
+ printk(KERN_WARNING
+ "node_to_cpumask(%d): node > nr_node_ids(%d)\n",
+ node, nr_node_ids);
+ dump_stack();
+ return cpu_mask_none;
+ }
return node_to_cpumask_map[node];
}
EXPORT_SYMBOL(node_to_cpumask);
--- linux-2.6.tip.orig/include/asm-x86/topology.h
+++ linux-2.6.tip/include/asm-x86/topology.h
@@ -57,7 +57,12 @@ static inline int cpu_to_node(int cpu)
}
#define early_cpu_to_node(cpu) cpu_to_node(cpu)

-/* Returns a bitmask of CPUs on Node 'node'. */
+/* Returns a bitmask of CPUs on Node 'node'.
+ *
+ * Side note: this function creates the returned cpumask on the stack
+ * so with a high NR_CPUS count, excessive stack space is used. The
+ * node_to_cpumask_ptr function should be used whenever possible.
+ */
static inline cpumask_t node_to_cpumask(int node)
{
return node_to_cpumask_map[node];

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