On Wed, Feb 13, 2019 at 05:00:16PM -0500, Waiman Long wrote:
Currently, we have two different implementation of rwsem: 1) CONFIG_RWSEM_GENERIC_SPINLOCK (rwsem-spinlock.c) 2) CONFIG_RWSEM_XCHGADD_ALGORITHM (rwsem-xadd.c) As we are going to use a single generic implementation for rwsem-xadd.c and no architecture-specific code will be needed, there is no point in keeping two different implementations of rwsem. In most cases, the performance of rwsem-spinlock.c will be worse. It also doesn't get all the performance tuning and optimizations that had been implemented in rwsem-xadd.c over the years. For simplication, we are going to remove rwsem-spinlock.c and make all architectures use a single implementation of rwsem - rwsem-xadd.c. All references to RWSEM_GENERIC_SPINLOCK and RWSEM_XCHGADD_ALGORITHM in the code are removed. Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Signed-off-by: Waiman Long <longman@xxxxxxxxxx> --- arch/alpha/Kconfig | 7 - arch/arc/Kconfig | 3 - arch/arm/Kconfig | 4 - arch/arm64/Kconfig | 3 - arch/c6x/Kconfig | 3 - arch/csky/Kconfig | 3 - arch/h8300/Kconfig | 3 - arch/hexagon/Kconfig | 6 - arch/ia64/Kconfig | 4 - arch/m68k/Kconfig | 7 - arch/microblaze/Kconfig | 6 - arch/mips/Kconfig | 7 - arch/nds32/Kconfig | 3 - arch/nios2/Kconfig | 3 - arch/openrisc/Kconfig | 6 - arch/parisc/Kconfig | 6 - arch/powerpc/Kconfig | 7 - arch/riscv/Kconfig | 3 - arch/s390/Kconfig | 6 - arch/sh/Kconfig | 6 - arch/sparc/Kconfig | 8 - arch/unicore32/Kconfig | 6 - arch/x86/Kconfig | 3 - arch/x86/um/Kconfig | 6 - arch/xtensa/Kconfig | 3 - include/linux/rwsem-spinlock.h | 47 ------ include/linux/rwsem.h | 5 - kernel/Kconfig.locks | 2 +- kernel/locking/Makefile | 4 +- kernel/locking/rwsem-spinlock.c | 339 ---------------------------------------- kernel/locking/rwsem.h | 3 - 31 files changed, 2 insertions(+), 520 deletions(-) delete mode 100644 include/linux/rwsem-spinlock.h delete mode 100644 kernel/locking/rwsem-spinlock.c
Another nice cleanup, and it looks like the optimistic spinning in the xadd implementation is predicated on ARCH_SUPPORTS_ATOMIC_RMW, so we're all good there too. Acked-by: Will Deacon <will.deacon@xxxxxxx> Will
