x86: prevent dereferencing non-allocated per_cpu variables

'for_each_possible_cpu(i)' when there's a _remote possibility_ of
dereferencing a non-allocated per_cpu variable involved.

All files except mm/vmstat.c are x86 arch.

Thanks to pageexec@freemail.hu for pointing this out.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <pageexec@freemail.hu>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/smp_32.c b/arch/x86/kernel/smp_32.c
index fcaa026..d4c01a4 100644 (file)
--- a/arch/x86/kernel/smp_32.c
+++ b/arch/x86/kernel/smp_32.c
@@ -223,7 +223,7 @@ void send_IPI_mask_sequence(cpumask_t mask, int vector)
         */ 
 
        local_irq_save(flags);
-       for (query_cpu = 0; query_cpu < NR_CPUS; ++query_cpu) {
+       for_each_possible_cpu(query_cpu) {
                if (cpu_isset(query_cpu, mask)) {
                        __send_IPI_dest_field(cpu_to_logical_apicid(query_cpu),
                                              vector);
@@ -675,7 +675,7 @@ static int convert_apicid_to_cpu(int apic_id)
 {
        int i;
 
-       for (i = 0; i < NR_CPUS; i++) {
+       for_each_possible_cpu(i) {
                if (per_cpu(x86_cpu_to_apicid, i) == apic_id)
                        return i;
        }

diff --git a/arch/x86/kernel/smpboot_32.c b/arch/x86/kernel/smpboot_32.c
index 239ada1..0bf7f20 100644 (file)
--- a/arch/x86/kernel/smpboot_32.c
+++ b/arch/x86/kernel/smpboot_32.c
@@ -1090,7 +1090,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
         * Allow the user to impress friends.
         */
        Dprintk("Before bogomips.\n");
-       for (cpu = 0; cpu < NR_CPUS; cpu++)
+       for_each_possible_cpu(cpu)
                if (cpu_isset(cpu, cpu_callout_map))
                        bogosum += cpu_data(cpu).loops_per_jiffy;
        printk(KERN_INFO
@@ -1121,7 +1121,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus)
         * construct cpu_sibling_map, so that we can tell sibling CPUs
         * efficiently.
         */
-       for (cpu = 0; cpu < NR_CPUS; cpu++) {
+       for_each_possible_cpu(cpu) {
                cpus_clear(per_cpu(cpu_sibling_map, cpu));
                cpus_clear(per_cpu(cpu_core_map, cpu));
        }

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index c1b131b..8e1234e 100644 (file)
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -146,7 +146,7 @@ void __init xen_smp_prepare_boot_cpu(void)
           old memory can be recycled */
        make_lowmem_page_readwrite(&per_cpu__gdt_page);
 
-       for (cpu = 0; cpu < NR_CPUS; cpu++) {
+       for_each_possible_cpu(cpu) {
                cpus_clear(per_cpu(cpu_sibling_map, cpu));
                /*
                 * cpu_core_map lives in a per cpu area that is cleared
@@ -163,7 +163,7 @@ void __init xen_smp_prepare_cpus(unsigned int max_cpus)
 {
        unsigned cpu;
 
-       for (cpu = 0; cpu < NR_CPUS; cpu++) {
+       for_each_possible_cpu(cpu) {
                cpus_clear(per_cpu(cpu_sibling_map, cpu));
                /*
                 * cpu_core_ map will be zeroed when the per