• Rusty Russell's avatar
    cpumask: introduce new API, without changing anything · 2d3854a3
    Rusty Russell authored
    Impact: introduce new APIs
    
    We want to deprecate cpumasks on the stack, as we are headed for
    gynormous numbers of CPUs.  Eventually, we want to head towards an
    undefined 'struct cpumask' so they can never be declared on stack.
    
    1) New cpumask functions which take pointers instead of copies.
       (cpus_* -> cpumask_*)
    
    2) Several new helpers to reduce requirements for temporary cpumasks
       (cpumask_first_and, cpumask_next_and, cpumask_any_and)
    
    3) Helpers for declaring cpumasks on or offstack for large NR_CPUS
       (cpumask_var_t, alloc_cpumask_var and free_cpumask_var)
    
    4) 'struct cpumask' for explicitness and to mark new-style code.
    
    5) Make iterator functions stop at nr_cpu_ids (a runtime constant),
       not NR_CPUS for time efficiency and for smaller dynamic allocations
       in future.
    
    6) cpumask_copy() so we can allocate less than a full cpumask eventually
       (for alloc_cpumask_var), and so we can eliminate the 'struct cpumask'
       definition eventually.
    
    7) work_on_cpu() helper for doing task on a CPU, rather than saving old
       cpumask for current thread and manipulating it.
    
    8) smp_call_function_many() which is smp_call_function_mask() except
       taking a cpumask pointer.
    
    Note that this patch simply introduces the new functions and leaves
    the obsolescent ones in place.  This is to simplify the transition
    patches.
    Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    2d3854a3
workqueue.c 24.9 KB