Re: [PATCH 2/2] sh, rwsem: drop superfluous arch specific implementation

Peter Zijlstra
2016-04-06T09:26:55Z

+Cc maintainers, linux-sh list is very high signal-to-noise as its been
appropriated for renesas arm parts.

On Mon, Apr 04, 2016 at 11:06:40AM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> since "locking, rwsem: drop explicit memory barriers" the arch specific
> code is basically same as the the generic one so we can drop the
> superfluous code.
>
> Suggested-by: Davidlohr Bueso <dave@stgolabs.net>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> arch/sh/include/asm/Kbuild | 1 +
> arch/sh/include/asm/rwsem.h | 130 --------------------------------------------
> 2 files changed, 1 insertion(+), 130 deletions(-)
> delete mode 100644 arch/sh/include/asm/rwsem.h
>
> diff --git a/arch/sh/include/asm/Kbuild b/arch/sh/include/asm/Kbuild
> index aac452b26aa8..6d866c7a9b74 100644
> --- a/arch/sh/include/asm/Kbuild
> +++ b/arch/sh/include/asm/Kbuild
> @@ -25,6 +25,7 @@ generic-y += percpu.h
> generic-y += poll.h
> generic-y += preempt.h
> generic-y += resource.h
> +generic-y += rwsem.h
> generic-y += sembuf.h
> generic-y += serial.h
> generic-y += shmbuf.h
> diff --git a/arch/sh/include/asm/rwsem.h b/arch/sh/include/asm/rwsem.h
> deleted file mode 100644
> index 8a457b83d2a5..000000000000
> --- a/arch/sh/include/asm/rwsem.h
> +++ /dev/null
> @@ -1,130 +0,0 @@
> -/*
> - * include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
> - * in lib/rwsem.c.
> - */
> -
> -#ifndef _ASM_SH_RWSEM_H
> -#define _ASM_SH_RWSEM_H
> -
> -#ifndef _LINUX_RWSEM_H
> -#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
> -#endif
> -
> -#ifdef __KERNEL__
> -
> -#define RWSEM_UNLOCKED_VALUE 0x00000000
> -#define RWSEM_ACTIVE_BIAS 0x00000001
> -#define RWSEM_ACTIVE_MASK 0x0000ffff
> -#define RWSEM_WAITING_BIAS (-0x00010000)
> -#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
> -#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
> -
> -/*
> - * lock for reading
> - */
> -static inline void __down_read(struct rw_semaphore *sem)
> -{
> - if (atomic_inc_return((atomic_t *)(&sem->count)) <= 0)
> - rwsem_down_read_failed(sem);
> -}
> -
> -static inline int __down_read_trylock(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - while ((tmp = sem->count) >= 0) {
> - if (tmp = cmpxchg(&sem->count, tmp,
> - tmp + RWSEM_ACTIVE_READ_BIAS)) {
> - return 1;
> - }
> - }
> - return 0;
> -}
> -
> -/*
> - * lock for writing
> - */
> -static inline void __down_write(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
> - (atomic_t *)(&sem->count));
> - if (tmp != RWSEM_ACTIVE_WRITE_BIAS)
> - rwsem_down_write_failed(sem);
> -}
> -
> -static inline int __down_write_killable(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
> - (atomic_t *)(&sem->count));
> - if (tmp != RWSEM_ACTIVE_WRITE_BIAS)
> - if (IS_ERR(rwsem_down_write_failed_killable(sem)))
> - return -EINTR;
> -
> - return 0;
> -}
> -
> -static inline int __down_write_trylock(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
> - RWSEM_ACTIVE_WRITE_BIAS);
> - return tmp = RWSEM_UNLOCKED_VALUE;
> -}
> -
> -/*
> - * unlock after reading
> - */
> -static inline void __up_read(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - tmp = atomic_dec_return((atomic_t *)(&sem->count));
> - if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) = 0)
> - rwsem_wake(sem);
> -}
> -
> -/*
> - * unlock after writing
> - */
> -static inline void __up_write(struct rw_semaphore *sem)
> -{
> - if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
> - (atomic_t *)(&sem->count)) < 0)
> - rwsem_wake(sem);
> -}
> -
> -/*
> - * implement atomic add functionality
> - */
> -static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
> -{
> - atomic_add(delta, (atomic_t *)(&sem->count));
> -}
> -
> -/*
> - * downgrade write lock to read lock
> - */
> -static inline void __downgrade_write(struct rw_semaphore *sem)
> -{
> - int tmp;
> -
> - tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
> - if (tmp < 0)
> - rwsem_downgrade_wake(sem);
> -}
> -
> -/*
> - * implement exchange and add functionality
> - */
> -static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
> -{
> - return atomic_add_return(delta, (atomic_t *)(&sem->count));
> -}
> -
> -#endif /* __KERNEL__ */
> -#endif /* _ASM_SH_RWSEM_H */
> --
> 2.8.0.rc3
>