linux/lib/closure.c, branch v6.8

closures: CLOSURE_CALLBACK() to fix type punning

2023-11-24T05:29:58Z

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 Cc: Coly Li Signed-off-by: Kent Overstreet

closures: Fix race in closure_sync()

2023-10-31T01:48:22Z

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

closures: Better memory barriers

2023-10-31T01:48:22Z

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

closures: Add a missing include

2023-10-19T18:47:33Z

Fixes building in userspace. Signed-off-by: Kent Overstreet

bcache: move closures to lib/

2023-10-19T18:47:33Z

Prep work for bcachefs - being a fork of bcache it also uses closures Signed-off-by: Kent Overstreet Acked-by: Coly Li Reviewed-by: Randy Dunlap