Enable qspinlock by the requirements mentioned in a8ad07e524
("asm-generic: qspinlock: Indicate the use of mixed-size atomics").
C-SKY only has "ldex/stex" for all atomic operations. So csky give a
strong forward guarantee for "ldex/stex." That means when ldex grabbed
the cache line into $L1, it would block other cores from snooping the
address with several cycles. The atomic_fetch_add & xchg16 has the same
forward guarantee level in C-SKY.
Qspinlock has better code size and performance in a fast path.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
There is no benefit from custom implementation for ticket-spinlock,
so move to generic ticket-spinlock for easy maintenance.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
