percpu_ref: make INIT_ATOMIC and switch_to_atomic() sticky
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: Tejun Heo <tj@kernel.org>
Reviewed-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
2 files changed