Messages in this thread | | | From | Linus Torvalds <> | Date | Mon, 6 Dec 2021 16:13:00 -0800 | Subject | Re: [PATCH] block: switch to atomic_t for request references |
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On Mon, Dec 6, 2021 at 3:28 PM Kees Cook <keescook@chromium.org> wrote: > > I'm not arguing for refcount_t -- I'm arguing for an API that isn't a > regression of features that have been protecting the kernel from bugs.
Maybe somebody could actually just fix refcount_t instead. Somebody who cares about that currently horrendously bad interface.
Fix it to not do the fundamentally broken saturation that actively destroys state: fix it to have a safe "try to increment", instead of an unsafe "increment and do bad things".
Fix it to not unnecessarily use expensive compare-and-exchange loops, when you can safely just race a bit, safe in the knowledge that you're not going to race 2**31 times.
IOW, I think that "try_get_page()" function is basically the *much* superior version of what is currently a broken "refcount_inc()".
And yes, it does warn about that overflow case that you claim only refcount_t does. And does so without the broken semantics that refcount h as.
Linus
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