Add a closure version of wait_event_timeout(), with the same semantics. The closure version is useful because unlike wait_event(), it allows blocking code to run in the conditional expression. Cc: Coly Li <colyli@suse.de> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
originally, stack closures were only used synchronously, and with the original implementation of closure_sync() the ref never hit 0; thus, closure_put_after_sub() assumes that if the ref hits 0 it's on the debug list, in debug mode. that's no longer true with the current implementation of closure_sync, so we need a new magic so closure_debug_destroy() doesn't pop an assert. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Provide new primitives for solving a lifetime issue with bcachefs btree_trans objects. closure_sync_return(): like closure_sync(), wait synchronously for any outstanding gets. like closure_return, the closure is considered "finished" and the ref left at 0. closure_get_not_zero(): get a ref on a closure if it's alive, i.e. the ref is not zero. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Add a new variant of closure_sync_timeout() that takes a timeout. Note that when this returns -ETIME the closure will still be waiting on something, i.e. it's not safe to return if you've got a stack allocated closure. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Control flow integrity is now checking that type signatures match on indirect function calls. That breaks closures, which embed a work_struct in a closure in such a way that a closure_fn may also be used as a workqueue fn by the underlying closure code. So we have to change closure fns to take a work_struct as their argument - but that results in a loss of clarity, as closure fns have different semantics from normal workqueue functions (they run owning a ref on the closure, which must be released with continue_at() or closure_return()). Thus, this patc introduces CLOSURE_CALLBACK() and closure_type() macros as suggested by Kees, to smooth things over a bit. Suggested-by: Kees Cook <keescook@chromium.org> Cc: Coly Li <colyli@suse.de> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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>
Factor out a new helper, which returns the number of events outstanding. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Like wait_event() - except, because it uses closures and closure waitlists it doesn't have the restriction on modifying task state inside the condition check, like wait_event() does. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Acked-by: Coly Li <colyli@suse.de>
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>