/* * A generic kernel FIFO implementation. * * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net> * Copyright (C) 2004 Stelian Pop <stelian@popies.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/err.h> #include <linux/kfifo.h> #include <linux/log2.h> #include <linux/uaccess.h> static void _kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size) { fifo->buffer = buffer; fifo->size = size; kfifo_reset(fifo); } /** * kfifo_init - initialize a FIFO using a preallocated buffer * @fifo: the fifo to assign the buffer * @buffer: the preallocated buffer to be used. * @size: the size of the internal buffer, this has to be a power of 2. * */ void kfifo_init(struct kfifo *fifo, void *buffer, unsigned int size) { /* size must be a power of 2 */ BUG_ON(!is_power_of_2(size)); _kfifo_init(fifo, buffer, size); } EXPORT_SYMBOL(kfifo_init); /** * kfifo_alloc - allocates a new FIFO internal buffer * @fifo: the fifo to assign then new buffer * @size: the size of the buffer to be allocated, this have to be a power of 2. * @gfp_mask: get_free_pages mask, passed to kmalloc() * * This function dynamically allocates a new fifo internal buffer * * The size will be rounded-up to a power of 2. * The buffer will be release with kfifo_free(). * Return 0 if no error, otherwise the an error code */ int kfifo_alloc(struct kfifo *fifo, unsigned int size, gfp_t gfp_mask) { unsigned char *buffer; /* * round up to the next power of 2, since our 'let the indices * wrap' technique works only in this case. */ if (!is_power_of_2(size)) { BUG_ON(size > 0x80000000); size = roundup_pow_of_two(size); } buffer = kmalloc(size, gfp_mask); if (!buffer) { _kfifo_init(fifo, NULL, 0); return -ENOMEM; } _kfifo_init(fifo, buffer, size); return 0; } EXPORT_SYMBOL(kfifo_alloc); /** * kfifo_free - frees the FIFO internal buffer * @fifo: the fifo to be freed. */ void kfifo_free(struct kfifo *fifo) { kfree(fifo->buffer); _kfifo_init(fifo, NULL, 0); } EXPORT_SYMBOL(kfifo_free); /** * kfifo_skip - skip output data * @fifo: the fifo to be used. * @len: number of bytes to skip */ void kfifo_skip(struct kfifo *fifo, unsigned int len) { if (len < kfifo_len(fifo)) { __kfifo_add_out(fifo, len); return; } kfifo_reset_out(fifo); } EXPORT_SYMBOL(kfifo_skip); static inline void __kfifo_in_data(struct kfifo *fifo, const void *from, unsigned int len, unsigned int off) { unsigned int l; /* * Ensure that we sample the fifo->out index -before- we * start putting bytes into the kfifo. */ smp_mb(); off = __kfifo_off(fifo, fifo->in + off); /* first put the data starting from fifo->in to buffer end */ l = min(len, fifo->size - off); memcpy(fifo->buffer + off, from, l); /* then put the rest (if any) at the beginning of the buffer */ memcpy(fifo->buffer, from + l, len - l); } static inline void __kfifo_out_data(struct kfifo *fifo, void *to, unsigned int len, unsigned int off) { unsigned int l; /* * Ensure that we sample the fifo->in index -before- we * start removing bytes from the kfifo. */ smp_rmb(); off = __kfifo_off(fifo, fifo->out + off); /* first get the data from fifo->out until the end of the buffer */ l = min(len, fifo->size - off); memcpy(to, fifo->buffer + off, l); /* then get the rest (if any) from the beginning of the buffer */ memcpy(to + l, fifo->buffer, len - l); } static inline int __kfifo_from_user_data(struct kfifo *fifo, const void __user *from, unsigned int len, unsigned int off, unsigned *lenout) { unsigned int l; int ret; /* * Ensure that we sample the fifo->out index -before- we * start putting bytes into the kfifo. */ smp_mb(); off = __kfifo_off(fifo, fifo->in + off); /* first put the data starting from fifo->in to buffer end */ l = min(len, fifo->size - off); ret = copy_from_user(fifo->buffer + off, from, l); if (unlikely(ret)) { *lenout = ret; return -EFAULT; } *lenout = l; /* then put the rest (if any) at the beginning of the buffer */ ret = copy_from_user(fifo->buffer, from + l, len - l); *lenout += ret ? ret : len - l; return ret ? -EFAULT : 0; } static inline int __kfifo_to_user_data(struct kfifo *fifo, void __user *to, unsigned int len, unsigned int off, unsigned *lenout) { unsigned int l; int ret; /* * Ensure that we sample the fifo->in index -before- we * start removing bytes from the kfifo. */ smp_rmb(); off = __kfifo_off(fifo, fifo->out + off); /* first get the data from fifo->out until the end of the buffer */ l = min(len, fifo->size - off); ret = copy_to_user(to, fifo->buffer + off, l); *lenout = l; if (unlikely(ret)) { *lenout -= ret; return -EFAULT; } /* then get the rest (if any) from the beginning of the buffer */ len -= l; ret = copy_to_user(to + l, fifo->buffer, len); if (unlikely(ret)) { *lenout += len - ret; return -EFAULT; } *lenout += len; return 0; } unsigned int __kfifo_in_n(struct kfifo *fifo, const void *from, unsigned int len, unsigned int recsize) { if (kfifo_avail(fifo) < len + recsize) return len + 1; __kfifo_in_data(fifo, from, len, recsize); return 0; } EXPORT_SYMBOL(__kfifo_in_n); /** * kfifo_in - puts some data into the FIFO * @fifo: the fifo to be used. * @from: the data to be added. * @len: the length of the data to be added. * * 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. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ unsigned int kfifo_in(struct kfifo *fifo, const void *from, unsigned int len) { len = min(kfifo_avail(fifo), len); __kfifo_in_data(fifo, from, len, 0); __kfifo_add_in(fifo, len); return len; } EXPORT_SYMBOL(kfifo_in); unsigned int __kfifo_in_generic(struct kfifo *fifo, const void *from, unsigned int len, unsigned int recsize) { return __kfifo_in_rec(fifo, from, len, recsize); } EXPORT_SYMBOL(__kfifo_in_generic); unsigned int __kfifo_out_n(struct kfifo *fifo, void *to, unsigned int len, unsigned int recsize) { if (kfifo_len(fifo) < len + recsize) return len; __kfifo_out_data(fifo, to, len, recsize); __kfifo_add_out(fifo, len + recsize); return 0; } EXPORT_SYMBOL(__kfifo_out_n); /** * kfifo_out - gets some data from the FIFO * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * * This function copies at most @len bytes from the FIFO into the * @to buffer and returns the number of copied bytes. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ unsigned int kfifo_out(struct kfifo *fifo, void *to, unsigned int len) { len = min(kfifo_len(fifo), len); __kfifo_out_data(fifo, to, len, 0); __kfifo_add_out(fifo, len); return len; } EXPORT_SYMBOL(kfifo_out); /** * kfifo_out_peek - copy some data from the FIFO, but do not remove it * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * @offset: offset into the fifo * * This function copies at most @len bytes at @offset from the FIFO * into the @to buffer and returns the number of copied bytes. * The data is not removed from the FIFO. */ unsigned int kfifo_out_peek(struct kfifo *fifo, void *to, unsigned int len, unsigned offset) { len = min(kfifo_len(fifo), len + offset); __kfifo_out_data(fifo, to, len, offset); return len; } EXPORT_SYMBOL(kfifo_out_peek); unsigned int __kfifo_out_generic(struct kfifo *fifo, void *to, unsigned int len, unsigned int recsize, unsigned int *total) { return __kfifo_out_rec(fifo, to, len, recsize, total); } EXPORT_SYMBOL(__kfifo_out_generic); unsigned int __kfifo_from_user_n(struct kfifo *fifo, const void __user *from, unsigned int len, unsigned int recsize) { unsigned total; if (kfifo_avail(fifo) < len + recsize) return len + 1; __kfifo_from_user_data(fifo, from, len, recsize, &total); return total; } EXPORT_SYMBOL(__kfifo_from_user_n); /** * kfifo_from_user - puts some data from user space into the FIFO * @fifo: the fifo to be used. * @from: pointer to the data to be added. * @len: the length of the data to be added. * @total: the actual returned data length. * * This function copies at most @len bytes from the @from into the * FIFO depending and returns -EFAULT/0. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ int kfifo_from_user(struct kfifo *fifo, const void __user *from, unsigned int len, unsigned *total) { int ret; len = min(kfifo_avail(fifo), len); ret = __kfifo_from_user_data(fifo, from, len, 0, total); if (ret) return ret; __kfifo_add_in(fifo, len); return 0; } EXPORT_SYMBOL(kfifo_from_user); unsigned int __kfifo_from_user_generic(struct kfifo *fifo, const void __user *from, unsigned int len, unsigned int recsize) { return __kfifo_from_user_rec(fifo, from, len, recsize); } EXPORT_SYMBOL(__kfifo_from_user_generic); unsigned int __kfifo_to_user_n(struct kfifo *fifo, void __user *to, unsigned int len, unsigned int reclen, unsigned int recsize) { unsigned int ret, total; if (kfifo_len(fifo) < reclen + recsize) return len; ret = __kfifo_to_user_data(fifo, to, reclen, recsize, &total); if (likely(ret == 0)) __kfifo_add_out(fifo, reclen + recsize); return total; } EXPORT_SYMBOL(__kfifo_to_user_n); /** * kfifo_to_user - gets data from the FIFO and write it to user space * @fifo: the fifo to be used. * @to: where the data must be copied. * @len: the size of the destination buffer. * @lenout: pointer to output variable with copied data * * This function copies at most @len bytes from the FIFO into the * @to buffer and 0 or -EFAULT. * * Note that with only one concurrent reader and one concurrent * writer, you don't need extra locking to use these functions. */ int kfifo_to_user(struct kfifo *fifo, void __user *to, unsigned int len, unsigned *lenout) { int ret; len = min(kfifo_len(fifo), len); ret = __kfifo_to_user_data(fifo, to, len, 0, lenout); __kfifo_add_out(fifo, *lenout); return ret; } EXPORT_SYMBOL(kfifo_to_user); unsigned int __kfifo_to_user_generic(struct kfifo *fifo, void __user *to, unsigned int len, unsigned int recsize, unsigned int *total) { return __kfifo_to_user_rec(fifo, to, len, recsize, total); } EXPORT_SYMBOL(__kfifo_to_user_generic); unsigned int __kfifo_peek_generic(struct kfifo *fifo, unsigned int recsize) { if (recsize == 0) return kfifo_avail(fifo); return __kfifo_peek_n(fifo, recsize); } EXPORT_SYMBOL(__kfifo_peek_generic); void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize) { __kfifo_skip_rec(fifo, recsize); } EXPORT_SYMBOL(__kfifo_skip_generic);