On Mon, 24 Jun 2013 12:58:25 +0100 Will Deacon <will.deacon@xxxxxxx> wrote: > On Fri, Jun 21, 2013 at 06:17:21PM +0100, Will Deacon wrote: > > This is an RFC cleanup series removing the unused > > arch_{spin,read,write}_relax macros from (nearly) all architectures that > > define them. The macros have no users in core code and are typically > > synonymous with cpu_relax(), the notable exceptions being PowerPC (where > > the thing is still unused) and S390. > > So the `no users in core code' part isn't quite true... > > With GENERIC_LOCKBREAK (arm64, ia64, m32r, parisc, powerpc, s390, sh and > sparc), we can actually spit out arch_*_relax calls in kernel/spinlock.c > using some macro concatenation that defeated my grep-fu. > > This only makes a difference on powerpc and s390, so we could either: > > (1) conditionally define the relax macros as cpu_relax in spinlock.c (so > the two guys above can have their special versions) > > (2) Replace the calls with calls to cpu_relax() (although powerpc seems to > want to know who owns the lock in order to relax) > > (3) Leave the current code alone for architectures that may select > GENERIC_LOCKBREAK > > Any other ideas/preferences? Yeah, we never came around to implement arch_read/write_relax. We can remove the two defines for s390, if we want to add some logic there we can just re-add an appropriate definition. As powerpc is optimizing their read/write locks with GENERIC_LOCKBREAK=y we should leave the ability to override the relax function as it is, no? -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html