Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c49a4955ea504c82f6b690491639bba5b8c1dc47
Commit:     c49a4955ea504c82f6b690491639bba5b8c1dc47
Parent:     602a54a8cab2759fceb20b3e0c2a27c4eac005df
Author:     [EMAIL PROTECTED] <[EMAIL PROTECTED]>
AuthorDate: Wed Jan 30 13:33:22 2008 +0100
Committer:  Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 13:33:22 2008 +0100

    x86: add debug of invalid per_cpu map accesses
    
    Provide a means to trap usages of per_cpu map variables before
    they are setup.  Define CONFIG_DEBUG_PER_CPU_MAPS to activate.
    
    Signed-off-by: Mike Travis <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
 arch/x86/Kconfig.debug     |   12 ++++++++++++
 arch/x86/mm/numa_64.c      |    3 +++
 include/asm-x86/topology.h |    7 +++++++
 3 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 88420af..0a82b88 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -47,6 +47,18 @@ config DEBUG_PAGEALLOC
          This results in a large slowdown, but helps to find certain types
          of memory corruptions.
 
+config DEBUG_PER_CPU_MAPS
+       bool "Debug access to per_cpu maps"
+       depends on DEBUG_KERNEL
+       depends on X86_64_SMP
+       default n
+       help
+         Say Y to verify that the per_cpu map being accessed has
+         been setup.  Adds a fair amount of code to kernel memory
+         and decreases performance.
+
+         Say N if unsure.
+
 config DEBUG_RODATA
        bool "Write protect kernel read-only data structures"
        depends on DEBUG_KERNEL
diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 5d24dc1..e157cb2 100644
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -37,6 +37,9 @@ u16 x86_cpu_to_node_map_init[NR_CPUS] = {
 void *x86_cpu_to_node_map_early_ptr;
 DEFINE_PER_CPU(u16, x86_cpu_to_node_map) = NUMA_NO_NODE;
 EXPORT_PER_CPU_SYMBOL(x86_cpu_to_node_map);
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+EXPORT_SYMBOL(x86_cpu_to_node_map_early_ptr);
+#endif
 
 u16 apicid_to_node[MAX_LOCAL_APIC] __cpuinitdata = {
        [0 ... MAX_LOCAL_APIC-1] = NUMA_NO_NODE
diff --git a/include/asm-x86/topology.h b/include/asm-x86/topology.h
index 040374f..f1e1232 100644
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -66,6 +66,13 @@ static inline int early_cpu_to_node(int cpu)
 
 static inline int cpu_to_node(int cpu)
 {
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+       if(x86_cpu_to_node_map_early_ptr) {
+               printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
+                       (int)cpu);
+               BUG();
+       }
+#endif
        if(per_cpu_offset(cpu))
                return per_cpu(x86_cpu_to_node_map, cpu);
        else
-
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