Messages in this thread |  | | | Date | Thu, 2 Jul 2009 09:21:57 +0200 | | From | Ingo Molnar <> | | Subject | Re: [PATCH] x86: Code atomic(64)_read and atomic(64)_set in C not CPP [was Re: FRV: Implement atomic64_t] |
* Paul Mackerras <paulus@samba.org> wrote:
> Occasionally we get bugs where atomic_read or atomic_set are used > on atomic64_t variables or vice versa. These bugs don't generate > warnings on x86 because atomic_read and atomic_set are coded as > macros rather than C functions, so we don't get any type-checking > on their arguments; similarly for atomic64_read and atomic64_set > in 64-bit kernels. > > This converts them to C functions so that the arguments are > type-checked and bugs like this will get caught more easily. It > also converts atomic_cmpxchg and atomic_xchg, and atomic64_cmpxchg > and atomic64_xchg on 64-bit, so we get type-checking on their > arguments too. > > Compiling a typical 64-bit x86 config, this generates no new > warnings, and the vmlinux text is 86 bytes smaller. > > Signed-off-by: Paul Mackerras <paulus@samba.org>
Thanks Paul!
> --- > Linus Torvalds writes: > > > Btw, Ingo: I looked at the x86-32 versions to be sure, and noticed a > > couple of buglets: > > > > - atomic64_xchg uses "atomic_read()". Sure, it happens to work, since > > the "atomic_read()" is not type-safe, and gets a non-atomic 64-bit > > read, but that looks really really bogus. > > > > It _should_ use __atomic64_read(), and the 64-bit versions should use a > > different counter name ("counter64"?) or we should use an inline > > function for atomic_read(), so that the type safety issue gets fixed. > > I did this patch a few weeks ago (before the merge window) and > sent it to Ingo, Thomas & Peter, but it seems to have got lost.
Yeah, as i noted back then off-list i didnt take it due to it causing a criss-cross merge:
| > Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> | | Nice - could someone please remind us later in the merge window to | have a look at this again? Right now this needs to go into | perfcounters/core - but i'd like to avoid having to do too many | cross-changes there.
Linus reminded us ;-)
Ingo
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