Messages in this thread Patch in this message | | | Date | Fri, 11 Jan 2019 10:24:08 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/3] bitops.h: set_mask_bits() to return old value |
| |
On Thu, Jan 10, 2019 at 04:26:27PM -0800, Vineet Gupta wrote:
> @@ -246,7 +246,7 @@ static __always_inline void __assign_bit(long nr, volatile unsigned long *addr, > new__ = (old__ & ~mask__) | bits__; \ > } while (cmpxchg(ptr, old__, new__) != old__); \
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 705f7c442691..2060d26a35f5 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -241,10 +241,10 @@ static __always_inline void __assign_bit(long nr, volatile unsigned long *addr, const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \ typeof(*(ptr)) old__, new__; \ \ + old__ = READ_ONCE(*(ptr)); \ do { \ - old__ = READ_ONCE(*(ptr)); \ new__ = (old__ & ~mask__) | bits__; \ - } while (cmpxchg(ptr, old__, new__) != old__); \ + } while (!try_cmpxchg(ptr, &old__, new__)); \ \ new__; \ })
While there you probably want something like the above... although, looking at it now, we seem to have 'forgotten' to add try_cmpxchg to the generic code :/
| |