Messages in this thread | | | Date | Thu, 16 Oct 2014 22:24:10 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] Fix the x86 specializations of atomic_[set|clear]_mask |
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On Thu, Oct 16, 2014 at 12:49:43PM -0400, Patrick Palka wrote: > On Oct 16, 2014 4:02 AM, "Peter Zijlstra" <peterz@infradead.org> wrote: > > > > On Wed, Oct 15, 2014 at 04:38:01PM -0400, Patrick Palka wrote: > > > This patch fixes a number of issues with these specializations: > > > > > > 1. The memory operand inside the asm specification is erroneously > > > declared read-only instead of read-write. > > > > > > 2. There is no reason to require the 1st operand of andl/orl to be > > > inside a register; the 1st operand could also be an immediate operand. > > > So change its specification from "r" to "ir". > > > > > > 3. Since addr is supposed to be an atomic_t *, the memory operand > > > should be addr->counter and not *addr. > > > > > > 4. These specializations should be inline functions instead of macros. > > > > > > 5. Finally, the "memory" clobbers are unnecessary, so they should be > > > removed. (This is in line with the other atomic functions such as > > > atomic_add and atomic_sub, the likes of which do not have a "memory" > > > clobber.) > > > > No real problem with this, but I'm going to kill off these functions > > when I get a little time :) > > Hmm why's that?
because they're odd (inconsistent with the rest of the atomic interfaces) and not implemented by all archs.
See: https://lkml.org/lkml/2014/2/6/196
3.18 will include up to 4/5 of that series and when I get a spare moment I need cleanup/post the next arch sweep that will get us that 5/5 thing.
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