On 7/23/20 9:30 AM, Nicholas Piggin wrote:
I would prefer to extract out the pending bit handling code out into a
separate helper function which can be overridden by the arch code
instead of breaking the slowpath into 2 pieces.
You mean have the arch provide a queued_spin_lock_slowpath_pending
function that the slow path calls?
I would actually prefer the pending handling can be made inline in
the queued_spin_lock function, especially with out-of-line locks it
makes sense to put it there.
We could ifdef out queued_spin_lock_slowpath_queue if it's not used,
then __queued_spin_lock_slowpath_queue would be inlined into the
caller so there would be no split?
The pending code is an optimization for lightly contended locks. That is
why I think it is appropriate to extract it into a helper function and
mark it as such.
You can certainly put the code in the arch's spin_lock code, you just
has to override the generic pending code by a null function.
Cheers,
Longman
