Messages in this thread Patch in this message | | | From | Vineet Gupta <> | Subject | [PATCH v2 3/3] bitops.h: set_mask_bits() to return old value | Date | Wed, 23 Jan 2019 12:33:04 -0800 |
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| > Also, set_mask_bits is used in fs quite a bit and we can possibly come up | > with a generic llsc based implementation (w/o the cmpxchg loop) | | May I also suggest changing the return value of set_mask_bits() to old. | | You can compute the new value given old, but you cannot compute the old | value given new, therefore old is the better return value. Also, no | current user seems to use the return value, so changing it is without | risk.
Link: http://lkml.kernel.org/g/20150807110955.GH16853@twins.programming.kicks-ass.net Suggested-by: Peter Zijlstra <peterz@infradead.org> Cc: Miklos Szeredi <mszeredi@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> --- include/linux/bitops.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/bitops.h b/include/linux/bitops.h index 705f7c442691..602af23b98c7 100644 --- a/include/linux/bitops.h +++ b/include/linux/bitops.h @@ -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__); \ \ - new__; \ + old__; \ }) #endif -- 2.7.4
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