• Tejun Heo's avatar
    percpu-refcount: implement percpu_ref_reinit() and percpu_ref_is_zero() · 2d722782
    Tejun Heo authored
    Now that explicit invocation of percpu_ref_exit() is necessary to free
    the percpu counter, we can implement percpu_ref_reinit() which
    reinitializes a released percpu_ref.  This can be used implement
    scalable gating switch which can be drained and then re-opened without
    worrying about memory allocation failures.
    
    percpu_ref_is_zero() is added to be used in a sanity check in
    percpu_ref_exit().  As this function will be useful for other purposes
    too, make it a public interface.
    
    v2: Use smp_read_barrier_depends() instead of smp_load_acquire().  We
        only need data dep barrier and smp_load_acquire() is stronger and
        heavier on some archs.  Spotted by Lai Jiangshan.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Cc: Kent Overstreet <kmo@daterainc.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    2d722782
percpu-refcount.c 6.29 KB