Messages in this thread | | | Date | Fri, 24 May 2019 12:42:20 +0100 | From | Will Deacon <> | Subject | Re: [PATCH 00/18] locking/atomic: atomic64 type cleanup |
| |
On Fri, May 24, 2019 at 01:18:07PM +0200, Peter Zijlstra wrote: > On Fri, May 24, 2019 at 12:37:31PM +0200, Peter Zijlstra wrote: > > On Thu, May 23, 2019 at 11:19:26AM +0100, Mark Rutland wrote: > > > > > [mark@lakrids:~/src/linux]% git grep '\(return\|=\)\s\+atomic\(64\)\?_set' > > > include/linux/vmw_vmci_defs.h: return atomic_set((atomic_t *)var, (u32)new_val); > > > include/linux/vmw_vmci_defs.h: return atomic64_set(var, new_val); > > > > > > > Oh boy, what a load of crap you just did find. > > > > How about something like the below? I've not read how that buffer is > > used, but the below preserves all broken without using atomic*_t. > > Clarified by something along these lines? > > --- > Documentation/atomic_t.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt > index dca3fb0554db..125c95ddbbc0 100644 > --- a/Documentation/atomic_t.txt > +++ b/Documentation/atomic_t.txt > @@ -83,6 +83,9 @@ The non-RMW ops are (typically) regular LOADs and STOREs and are canonically > implemented using READ_ONCE(), WRITE_ONCE(), smp_load_acquire() and > smp_store_release() respectively. >
Not sure you need a new paragraph here.
> +Therefore, if you find yourself only using the Non-RMW operations of atomic_t, > +you do not in fact need atomic_t at all and are doing it wrong. > +
That makes sense to me, although I now find that the sentence below is a bit confusing because it sounds like it's a caveat relating to only using Non-RMW ops.
> The one detail to this is that atomic_set{}() should be observable to the RMW > ops. That is:
How about changing this to be:
"A subtle detail of atomic_set{}() is that it should be observable..."
With that:
Acked-by: Will Deacon <will.deacon@arm.com>
Will
| |