powerpc/qspinlock: Optimised atomic_try_cmpxchg_lock() that adds the lock hint
authorNicholas Piggin <npiggin@gmail.com>
Fri, 24 Jul 2020 13:14:22 +0000 (23:14 +1000)
committerMichael Ellerman <mpe@ellerman.id.au>
Sun, 26 Jul 2020 14:01:29 +0000 (00:01 +1000)
commit2f6560e652dfdbdb59df28b45a3458bf36d3c580
treeeb923dd64c883cf1cbd977111baf6a146ad55e23
parent20c0e8269e9d515e677670902c7e1cc0209d6ad9
powerpc/qspinlock: Optimised atomic_try_cmpxchg_lock() that adds the lock hint

This brings the behaviour of the uncontended fast path back to roughly
equivalent to simple spinlocks -- a single atomic op with lock hint.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200724131423.1362108-6-npiggin@gmail.com
arch/powerpc/include/asm/atomic.h
arch/powerpc/include/asm/qspinlock.h