• Tejun Heo's avatar
    percpu_ref: make INIT_ATOMIC and switch_to_atomic() sticky · 1cae13e7
    Tejun Heo authored
    Currently, a percpu_ref which is initialized with
    PERPCU_REF_INIT_ATOMIC or switched to atomic mode via
    switch_to_atomic() automatically reverts to percpu mode on the first
    percpu_ref_reinit().  This makes the atomic mode difficult to use for
    cases where a percpu_ref is used as a persistent on/off switch which
    may be cycled multiple times.
    
    This patch makes such atomic state sticky so that it survives through
    kill/reinit cycles.  After this patch, atomic state is cleared only by
    an explicit percpu_ref_switch_to_percpu() call.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Reviewed-by: default avatarKent Overstreet <kmo@daterainc.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: Christoph Hellwig <hch@infradead.org>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    1cae13e7
percpu-refcount.c 11.7 KB