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    Subject[PATCH 14/35] cpumask: make nr_cpu_ids valid in all configurations.
    nr_cpu_ids is the (badly named) runtime limit on possible CPU numbers;
    ie. the variable version of NR_CPUS.

    This makes is valid in all configs, including UP.

    From: Rusty Russell <rusty@rustcorp.com.au>
    Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
    Signed-off-by: Mike Travis <travis@sgi.com>
    ---
    include/linux/cpumask.h | 10 ++++++++--
    init/main.c | 7 +++++++
    2 files changed, 15 insertions(+), 2 deletions(-)
    --- test-compile.orig/include/linux/cpumask.h
    +++ test-compile/include/linux/cpumask.h
    @@ -195,6 +195,14 @@ extern cpumask_t _unused_cpumask_arg_;
    #define cpus_addr(src) ((src).bits)
    /* End deprecated region. */

    +#if NR_CPUS <= BITS_PER_LONG
    +/* Constant is usually more efficient than a variable for small NR_CPUS */
    +#define nr_cpu_ids NR_CPUS
    +#else
    +/* Starts at NR_CPUS until we know better. */
    +extern int nr_cpu_ids;
    +#endif /* NR_CPUS > BITS_PER_LONG */
    +
    static inline void cpumask_set_cpu(int cpu, volatile struct cpumask *dstp)
    {
    set_bit(cpu, dstp->bits);
    @@ -434,7 +442,6 @@ extern cpumask_t cpu_mask_all;

    #if NR_CPUS == 1

    -#define nr_cpu_ids 1
    #define first_cpu(src) ({ (void)(src); 0; })
    #define next_cpu(n, src) ({ (void)(src); 1; })
    #define cpumask_next_and(n, srcp, andp) ({ (void)(srcp), (void)(andp); 1; })
    @@ -447,7 +454,6 @@ extern cpumask_t cpu_mask_all;

    #else /* NR_CPUS > 1 */

    -extern int nr_cpu_ids;
    int __first_cpu(const cpumask_t *srcp);
    int __next_cpu(int n, const cpumask_t *srcp);
    int cpumask_next_and(int n, const cpumask_t *srcp, const cpumask_t *andp);
    --- test-compile.orig/init/main.c
    +++ test-compile/init/main.c
    @@ -373,6 +373,8 @@ EXPORT_SYMBOL(cpu_mask_all);
    #endif

    /* Setup number of possible processor ids */
    +/* nr_cpu_ids is a real variable for large NR_CPUS. */
    +#ifndef nr_cpu_ids
    int nr_cpu_ids __read_mostly = NR_CPUS;
    EXPORT_SYMBOL(nr_cpu_ids);

    @@ -386,6 +388,11 @@ void __init setup_nr_cpu_ids(void)

    nr_cpu_ids = highest_cpu + 1;
    }
    +#else
    +void __init setup_nr_cpu_ids(void)
    +{
    +}
    +#endif /* ... nr_cpu_ids is a constant. */

    #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
    unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
    --


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