From c1e13f25674ed564948ecb7dfe5f83e578892896 Mon Sep 17 00:00:00 2001 From: Stefani Seibold Date: Mon, 21 Dec 2009 14:37:27 -0800 Subject: kfifo: move out spinlock Move the pointer to the spinlock out of struct kfifo. Most users in tree do not actually use a spinlock, so the few exceptions now have to call kfifo_{get,put}_locked, which takes an extra argument to a spinlock. Signed-off-by: Stefani Seibold Acked-by: Greg Kroah-Hartman Acked-by: Mauro Carvalho Chehab Acked-by: Andi Kleen Acked-by: Arnd Bergmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kfifo.h | 80 ++++++++++++++++++++++----------------------------- 1 file changed, 35 insertions(+), 45 deletions(-) (limited to 'include') diff --git a/include/linux/kfifo.h b/include/linux/kfifo.h index c3f8d82efd34..e0f5c9d4197d 100644 --- a/include/linux/kfifo.h +++ b/include/linux/kfifo.h @@ -30,13 +30,12 @@ struct kfifo { unsigned int size; /* the size of the allocated buffer */ unsigned int in; /* data is added at offset (in % size) */ unsigned int out; /* data is extracted from off. (out % size) */ - spinlock_t *lock; /* protects concurrent modifications */ }; extern void kfifo_init(struct kfifo *fifo, unsigned char *buffer, - unsigned int size, spinlock_t *lock); + unsigned int size); extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size, - gfp_t gfp_mask, spinlock_t *lock); + gfp_t gfp_mask); extern void kfifo_free(struct kfifo *fifo); extern unsigned int __kfifo_put(struct kfifo *fifo, const unsigned char *buffer, unsigned int len); @@ -58,58 +57,67 @@ static inline void __kfifo_reset(struct kfifo *fifo) */ static inline void kfifo_reset(struct kfifo *fifo) { - unsigned long flags; - - spin_lock_irqsave(fifo->lock, flags); - __kfifo_reset(fifo); +} + +/** + * __kfifo_len - returns the number of bytes available in the FIFO + * @fifo: the fifo to be used. + */ +static inline unsigned int __kfifo_len(struct kfifo *fifo) +{ + register unsigned int out; - spin_unlock_irqrestore(fifo->lock, flags); + out = fifo->out; + smp_rmb(); + return fifo->in - out; } /** - * kfifo_put - puts some data into the FIFO + * kfifo_put_locked - puts some data into the FIFO using a spinlock for locking * @fifo: the fifo to be used. - * @buffer: the data to be added. - * @len: the length of the data to be added. + * @from: the data to be added. + * @n: the length of the data to be added. + * @lock: pointer to the spinlock to use for locking. * - * This function copies at most @len bytes from the @buffer into + * This function copies at most @len bytes from the @from buffer into * the FIFO depending on the free space, and returns the number of * bytes copied. */ -static inline unsigned int kfifo_put(struct kfifo *fifo, - const unsigned char *buffer, unsigned int len) +static inline __must_check unsigned int kfifo_put_locked(struct kfifo *fifo, + const unsigned char *from, unsigned int n, spinlock_t *lock) { unsigned long flags; unsigned int ret; - spin_lock_irqsave(fifo->lock, flags); + spin_lock_irqsave(lock, flags); - ret = __kfifo_put(fifo, buffer, len); + ret = __kfifo_put(fifo, from, n); - spin_unlock_irqrestore(fifo->lock, flags); + spin_unlock_irqrestore(lock, flags); return ret; } /** - * kfifo_get - gets some data from the FIFO + * kfifo_get_locked - gets some data from the FIFO using a spinlock for locking * @fifo: the fifo to be used. - * @buffer: where the data must be copied. - * @len: the size of the destination buffer. + * @to: where the data must be copied. + * @n: the size of the destination buffer. + * @lock: pointer to the spinlock to use for locking. * * This function copies at most @len bytes from the FIFO into the - * @buffer and returns the number of copied bytes. + * @to buffer and returns the number of copied bytes. */ -static inline unsigned int kfifo_get(struct kfifo *fifo, - unsigned char *buffer, unsigned int len) +static inline __must_check unsigned int kfifo_get_locked(struct kfifo *fifo, + unsigned char *to, unsigned int n, spinlock_t *lock) { unsigned long flags; unsigned int ret; - spin_lock_irqsave(fifo->lock, flags); + spin_lock_irqsave(lock, flags); - ret = __kfifo_get(fifo, buffer, len); + ret = __kfifo_get(fifo, to, n); /* * optimization: if the FIFO is empty, set the indices to 0 @@ -118,36 +126,18 @@ static inline unsigned int kfifo_get(struct kfifo *fifo, if (fifo->in == fifo->out) fifo->in = fifo->out = 0; - spin_unlock_irqrestore(fifo->lock, flags); + spin_unlock_irqrestore(lock, flags); return ret; } -/** - * __kfifo_len - returns the number of bytes available in the FIFO, no locking version - * @fifo: the fifo to be used. - */ -static inline unsigned int __kfifo_len(struct kfifo *fifo) -{ - return fifo->in - fifo->out; -} - /** * kfifo_len - returns the number of bytes available in the FIFO * @fifo: the fifo to be used. */ static inline unsigned int kfifo_len(struct kfifo *fifo) { - unsigned long flags; - unsigned int ret; - - spin_lock_irqsave(fifo->lock, flags); - - ret = __kfifo_len(fifo); - - spin_unlock_irqrestore(fifo->lock, flags); - - return ret; + return __kfifo_len(fifo); } #endif -- cgit v1.2.3