Hi,-
Back when we were discussing the need for a memory barrier in sync_page(), it came to me (thanks Andrea!) that the bit operations can be perfectly reordered on architectures other than x86.
I think the commentary on i386 bitops.h is misleading, its worth to note that that these operations are not guaranteed not to be reordered on different architectures.
clear_bit() already does that:
* clear_bit() is atomic and may not be reordered. However, it does
* not contain a memory barrier, so if it is used for locking purposes,
* you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
* in order to ensure changes are visible on other processors.
What you think of the following