As pointed out by Linus, closure_sync() was racy; we could skip blocking
immediately after a get() and a put(), but then that would skip any
barrier corresponding to the other thread's put() barrier.
To fix this, always do the full __closure_sync() sequence whenever any
get() has happened and the closure might have been used by other
threads.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
atomic_(dec|sub)_return_release() are a thing now - use them.
Also, delete the useless barrier in set_closure_fn(): it's redundant
with the memory barrier in closure_put(0.
Since closure_put() would now otherwise just have a release barrier, we
also need a new barrier when the ref hits 0 -
smp_acquire__after_ctrl_dep().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Prep work for bcachefs - being a fork of bcache it also uses closures
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Acked-by: Coly Li <colyli@suse.de>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
