Messages in this thread | | | Date | Mon, 2 Jun 2014 13:53:48 -0700 | Subject | Re: [PATCH v2] introduce atomic_pointer to fix a race condition in cancelable mcs spinlocks | From | Linus Torvalds <> |
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On Mon, Jun 2, 2014 at 1:46 PM, Mikulas Patocka <mpatocka@redhat.com> wrote: > > And what else do you want to do? > > Peter Zijlstra said "I've been using xchg() and cmpxchg() without such > consideration for quite a while." - so it basically implies that the > kernel is full of such races, mcs_spinlock is just the most visible one > that crashes the kernel first.
.. so your whole argument is bogus, because it doesn't actually fix anything else.
Now, something that *would* fix something else is (for example) to just make "ACCESS_ONCE()" a rvalue so that you cannot use it for assignments, and then trying to sort out what happens then. It's possible that the "atomic_pointer_t" would be a part of the solution to that "what happens then", but THERE IS NO WAY IN HELL we're adding it for just one architecture and one use that doesn't warrant even _existing_ on that architecture.
See what I'm saying?
You're not fixing the problem, you're fixing one unimportant detail that isn't worth fixing that way.
Linus
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