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![Geert Uytterhoeven](/assets/img/avatar_default.png)
Add the missing closing parenthesis to the description for the to_buffer parameter of sg_copy_buffer(). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Akinobu Mita <akinobu.mita@gmail.com Link: http://lkml.kernel.org/r/20200212084241.8778-1-geert+renesas@glider.be Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
979 lines
25 KiB
C
979 lines
25 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2007 Jens Axboe <jens.axboe@oracle.com>
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*
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* Scatterlist handling helpers.
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*/
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/scatterlist.h>
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#include <linux/highmem.h>
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#include <linux/kmemleak.h>
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/**
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* sg_next - return the next scatterlist entry in a list
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* @sg: The current sg entry
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*
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* Description:
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* Usually the next entry will be @sg@ + 1, but if this sg element is part
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* of a chained scatterlist, it could jump to the start of a new
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* scatterlist array.
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*
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**/
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struct scatterlist *sg_next(struct scatterlist *sg)
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{
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if (sg_is_last(sg))
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return NULL;
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sg++;
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if (unlikely(sg_is_chain(sg)))
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sg = sg_chain_ptr(sg);
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return sg;
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}
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EXPORT_SYMBOL(sg_next);
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/**
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* sg_nents - return total count of entries in scatterlist
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* @sg: The scatterlist
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*
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* Description:
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* Allows to know how many entries are in sg, taking into acount
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* chaining as well
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*
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**/
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int sg_nents(struct scatterlist *sg)
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{
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int nents;
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for (nents = 0; sg; sg = sg_next(sg))
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nents++;
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return nents;
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}
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EXPORT_SYMBOL(sg_nents);
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/**
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* sg_nents_for_len - return total count of entries in scatterlist
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* needed to satisfy the supplied length
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* @sg: The scatterlist
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* @len: The total required length
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*
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* Description:
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* Determines the number of entries in sg that are required to meet
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* the supplied length, taking into acount chaining as well
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*
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* Returns:
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* the number of sg entries needed, negative error on failure
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*
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**/
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int sg_nents_for_len(struct scatterlist *sg, u64 len)
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{
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int nents;
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u64 total;
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if (!len)
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return 0;
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for (nents = 0, total = 0; sg; sg = sg_next(sg)) {
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nents++;
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total += sg->length;
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if (total >= len)
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return nents;
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}
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return -EINVAL;
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}
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EXPORT_SYMBOL(sg_nents_for_len);
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/**
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* sg_last - return the last scatterlist entry in a list
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* @sgl: First entry in the scatterlist
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* @nents: Number of entries in the scatterlist
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*
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* Description:
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* Should only be used casually, it (currently) scans the entire list
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* to get the last entry.
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*
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* Note that the @sgl@ pointer passed in need not be the first one,
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* the important bit is that @nents@ denotes the number of entries that
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* exist from @sgl@.
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*
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**/
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struct scatterlist *sg_last(struct scatterlist *sgl, unsigned int nents)
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{
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struct scatterlist *sg, *ret = NULL;
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unsigned int i;
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for_each_sg(sgl, sg, nents, i)
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ret = sg;
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BUG_ON(!sg_is_last(ret));
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return ret;
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}
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EXPORT_SYMBOL(sg_last);
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/**
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* sg_init_table - Initialize SG table
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* @sgl: The SG table
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* @nents: Number of entries in table
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*
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* Notes:
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* If this is part of a chained sg table, sg_mark_end() should be
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* used only on the last table part.
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*
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**/
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void sg_init_table(struct scatterlist *sgl, unsigned int nents)
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{
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memset(sgl, 0, sizeof(*sgl) * nents);
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sg_init_marker(sgl, nents);
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}
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EXPORT_SYMBOL(sg_init_table);
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/**
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* sg_init_one - Initialize a single entry sg list
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* @sg: SG entry
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* @buf: Virtual address for IO
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* @buflen: IO length
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*
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**/
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void sg_init_one(struct scatterlist *sg, const void *buf, unsigned int buflen)
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{
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sg_init_table(sg, 1);
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sg_set_buf(sg, buf, buflen);
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}
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EXPORT_SYMBOL(sg_init_one);
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/*
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* The default behaviour of sg_alloc_table() is to use these kmalloc/kfree
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* helpers.
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*/
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static struct scatterlist *sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
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{
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if (nents == SG_MAX_SINGLE_ALLOC) {
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/*
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* Kmemleak doesn't track page allocations as they are not
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* commonly used (in a raw form) for kernel data structures.
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* As we chain together a list of pages and then a normal
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* kmalloc (tracked by kmemleak), in order to for that last
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* allocation not to become decoupled (and thus a
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* false-positive) we need to inform kmemleak of all the
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* intermediate allocations.
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*/
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void *ptr = (void *) __get_free_page(gfp_mask);
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kmemleak_alloc(ptr, PAGE_SIZE, 1, gfp_mask);
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return ptr;
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} else
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return kmalloc_array(nents, sizeof(struct scatterlist),
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gfp_mask);
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}
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static void sg_kfree(struct scatterlist *sg, unsigned int nents)
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{
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if (nents == SG_MAX_SINGLE_ALLOC) {
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kmemleak_free(sg);
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free_page((unsigned long) sg);
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} else
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kfree(sg);
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}
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/**
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* __sg_free_table - Free a previously mapped sg table
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* @table: The sg table header to use
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* @max_ents: The maximum number of entries per single scatterlist
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* @nents_first_chunk: Number of entries int the (preallocated) first
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* scatterlist chunk, 0 means no such preallocated first chunk
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* @free_fn: Free function
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*
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* Description:
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* Free an sg table previously allocated and setup with
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* __sg_alloc_table(). The @max_ents value must be identical to
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* that previously used with __sg_alloc_table().
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*
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**/
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void __sg_free_table(struct sg_table *table, unsigned int max_ents,
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unsigned int nents_first_chunk, sg_free_fn *free_fn)
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{
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struct scatterlist *sgl, *next;
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unsigned curr_max_ents = nents_first_chunk ?: max_ents;
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if (unlikely(!table->sgl))
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return;
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sgl = table->sgl;
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while (table->orig_nents) {
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unsigned int alloc_size = table->orig_nents;
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unsigned int sg_size;
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/*
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* If we have more than max_ents segments left,
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* then assign 'next' to the sg table after the current one.
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* sg_size is then one less than alloc size, since the last
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* element is the chain pointer.
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*/
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if (alloc_size > curr_max_ents) {
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next = sg_chain_ptr(&sgl[curr_max_ents - 1]);
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alloc_size = curr_max_ents;
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sg_size = alloc_size - 1;
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} else {
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sg_size = alloc_size;
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next = NULL;
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}
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table->orig_nents -= sg_size;
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if (nents_first_chunk)
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nents_first_chunk = 0;
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else
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free_fn(sgl, alloc_size);
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sgl = next;
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curr_max_ents = max_ents;
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}
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table->sgl = NULL;
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}
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EXPORT_SYMBOL(__sg_free_table);
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/**
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* sg_free_table - Free a previously allocated sg table
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* @table: The mapped sg table header
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*
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**/
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void sg_free_table(struct sg_table *table)
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{
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__sg_free_table(table, SG_MAX_SINGLE_ALLOC, false, sg_kfree);
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}
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EXPORT_SYMBOL(sg_free_table);
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/**
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* __sg_alloc_table - Allocate and initialize an sg table with given allocator
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @max_ents: The maximum number of entries the allocator returns per call
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* @nents_first_chunk: Number of entries int the (preallocated) first
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* scatterlist chunk, 0 means no such preallocated chunk provided by user
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* @gfp_mask: GFP allocation mask
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* @alloc_fn: Allocator to use
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*
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* Description:
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* This function returns a @table @nents long. The allocator is
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* defined to return scatterlist chunks of maximum size @max_ents.
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* Thus if @nents is bigger than @max_ents, the scatterlists will be
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* chained in units of @max_ents.
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*
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* Notes:
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* If this function returns non-0 (eg failure), the caller must call
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* __sg_free_table() to cleanup any leftover allocations.
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*
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**/
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int __sg_alloc_table(struct sg_table *table, unsigned int nents,
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unsigned int max_ents, struct scatterlist *first_chunk,
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unsigned int nents_first_chunk, gfp_t gfp_mask,
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sg_alloc_fn *alloc_fn)
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{
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struct scatterlist *sg, *prv;
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unsigned int left;
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unsigned curr_max_ents = nents_first_chunk ?: max_ents;
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unsigned prv_max_ents;
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memset(table, 0, sizeof(*table));
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if (nents == 0)
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return -EINVAL;
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#ifdef CONFIG_ARCH_NO_SG_CHAIN
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if (WARN_ON_ONCE(nents > max_ents))
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return -EINVAL;
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#endif
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left = nents;
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prv = NULL;
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do {
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unsigned int sg_size, alloc_size = left;
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if (alloc_size > curr_max_ents) {
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alloc_size = curr_max_ents;
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sg_size = alloc_size - 1;
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} else
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sg_size = alloc_size;
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left -= sg_size;
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if (first_chunk) {
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sg = first_chunk;
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first_chunk = NULL;
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} else {
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sg = alloc_fn(alloc_size, gfp_mask);
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}
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if (unlikely(!sg)) {
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/*
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* Adjust entry count to reflect that the last
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* entry of the previous table won't be used for
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* linkage. Without this, sg_kfree() may get
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* confused.
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*/
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if (prv)
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table->nents = ++table->orig_nents;
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return -ENOMEM;
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}
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sg_init_table(sg, alloc_size);
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table->nents = table->orig_nents += sg_size;
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/*
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* If this is the first mapping, assign the sg table header.
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* If this is not the first mapping, chain previous part.
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*/
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if (prv)
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sg_chain(prv, prv_max_ents, sg);
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else
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table->sgl = sg;
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/*
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* If no more entries after this one, mark the end
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*/
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if (!left)
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sg_mark_end(&sg[sg_size - 1]);
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prv = sg;
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prv_max_ents = curr_max_ents;
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curr_max_ents = max_ents;
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} while (left);
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return 0;
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}
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EXPORT_SYMBOL(__sg_alloc_table);
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/**
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* sg_alloc_table - Allocate and initialize an sg table
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* @table: The sg table header to use
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* @nents: Number of entries in sg list
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* @gfp_mask: GFP allocation mask
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*
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* Description:
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* Allocate and initialize an sg table. If @nents@ is larger than
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* SG_MAX_SINGLE_ALLOC a chained sg table will be setup.
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*
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**/
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int sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
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{
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int ret;
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ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
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NULL, 0, gfp_mask, sg_kmalloc);
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if (unlikely(ret))
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__sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
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return ret;
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}
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EXPORT_SYMBOL(sg_alloc_table);
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/**
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* __sg_alloc_table_from_pages - Allocate and initialize an sg table from
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* an array of pages
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* @sgt: The sg table header to use
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* @pages: Pointer to an array of page pointers
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* @n_pages: Number of pages in the pages array
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* @offset: Offset from start of the first page to the start of a buffer
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* @size: Number of valid bytes in the buffer (after offset)
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* @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
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* @gfp_mask: GFP allocation mask
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*
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* Description:
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* Allocate and initialize an sg table from a list of pages. Contiguous
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* ranges of the pages are squashed into a single scatterlist node up to the
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* maximum size specified in @max_segment. An user may provide an offset at a
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* start and a size of valid data in a buffer specified by the page array.
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* The returned sg table is released by sg_free_table.
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*
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* Returns:
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* 0 on success, negative error on failure
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*/
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int __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
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unsigned int n_pages, unsigned int offset,
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unsigned long size, unsigned int max_segment,
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gfp_t gfp_mask)
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{
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unsigned int chunks, cur_page, seg_len, i;
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int ret;
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struct scatterlist *s;
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if (WARN_ON(!max_segment || offset_in_page(max_segment)))
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return -EINVAL;
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/* compute number of contiguous chunks */
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chunks = 1;
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seg_len = 0;
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for (i = 1; i < n_pages; i++) {
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seg_len += PAGE_SIZE;
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if (seg_len >= max_segment ||
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page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
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chunks++;
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seg_len = 0;
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}
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}
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ret = sg_alloc_table(sgt, chunks, gfp_mask);
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if (unlikely(ret))
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return ret;
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/* merging chunks and putting them into the scatterlist */
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cur_page = 0;
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for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
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unsigned int j, chunk_size;
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/* look for the end of the current chunk */
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seg_len = 0;
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for (j = cur_page + 1; j < n_pages; j++) {
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seg_len += PAGE_SIZE;
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if (seg_len >= max_segment ||
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page_to_pfn(pages[j]) !=
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page_to_pfn(pages[j - 1]) + 1)
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break;
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}
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chunk_size = ((j - cur_page) << PAGE_SHIFT) - offset;
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sg_set_page(s, pages[cur_page],
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min_t(unsigned long, size, chunk_size), offset);
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size -= chunk_size;
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offset = 0;
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cur_page = j;
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}
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return 0;
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}
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EXPORT_SYMBOL(__sg_alloc_table_from_pages);
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/**
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* sg_alloc_table_from_pages - Allocate and initialize an sg table from
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* an array of pages
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* @sgt: The sg table header to use
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* @pages: Pointer to an array of page pointers
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* @n_pages: Number of pages in the pages array
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* @offset: Offset from start of the first page to the start of a buffer
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* @size: Number of valid bytes in the buffer (after offset)
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* @gfp_mask: GFP allocation mask
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*
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* Description:
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* Allocate and initialize an sg table from a list of pages. Contiguous
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* ranges of the pages are squashed into a single scatterlist node. A user
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* may provide an offset at a start and a size of valid data in a buffer
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* specified by the page array. The returned sg table is released by
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* sg_free_table.
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*
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* Returns:
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* 0 on success, negative error on failure
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*/
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int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
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unsigned int n_pages, unsigned int offset,
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unsigned long size, gfp_t gfp_mask)
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{
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return __sg_alloc_table_from_pages(sgt, pages, n_pages, offset, size,
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SCATTERLIST_MAX_SEGMENT, gfp_mask);
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}
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EXPORT_SYMBOL(sg_alloc_table_from_pages);
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#ifdef CONFIG_SGL_ALLOC
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/**
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* sgl_alloc_order - allocate a scatterlist and its pages
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* @length: Length in bytes of the scatterlist. Must be at least one
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* @order: Second argument for alloc_pages()
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* @chainable: Whether or not to allocate an extra element in the scatterlist
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* for scatterlist chaining purposes
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* @gfp: Memory allocation flags
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* @nent_p: [out] Number of entries in the scatterlist that have pages
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*
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* Returns: A pointer to an initialized scatterlist or %NULL upon failure.
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*/
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struct scatterlist *sgl_alloc_order(unsigned long long length,
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unsigned int order, bool chainable,
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gfp_t gfp, unsigned int *nent_p)
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{
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struct scatterlist *sgl, *sg;
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struct page *page;
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unsigned int nent, nalloc;
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u32 elem_len;
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nent = round_up(length, PAGE_SIZE << order) >> (PAGE_SHIFT + order);
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/* Check for integer overflow */
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if (length > (nent << (PAGE_SHIFT + order)))
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return NULL;
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nalloc = nent;
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if (chainable) {
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/* Check for integer overflow */
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if (nalloc + 1 < nalloc)
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return NULL;
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nalloc++;
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}
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sgl = kmalloc_array(nalloc, sizeof(struct scatterlist),
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(gfp & ~GFP_DMA) | __GFP_ZERO);
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if (!sgl)
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return NULL;
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|
|
sg_init_table(sgl, nalloc);
|
|
sg = sgl;
|
|
while (length) {
|
|
elem_len = min_t(u64, length, PAGE_SIZE << order);
|
|
page = alloc_pages(gfp, order);
|
|
if (!page) {
|
|
sgl_free(sgl);
|
|
return NULL;
|
|
}
|
|
|
|
sg_set_page(sg, page, elem_len, 0);
|
|
length -= elem_len;
|
|
sg = sg_next(sg);
|
|
}
|
|
WARN_ONCE(length, "length = %lld\n", length);
|
|
if (nent_p)
|
|
*nent_p = nent;
|
|
return sgl;
|
|
}
|
|
EXPORT_SYMBOL(sgl_alloc_order);
|
|
|
|
/**
|
|
* sgl_alloc - allocate a scatterlist and its pages
|
|
* @length: Length in bytes of the scatterlist
|
|
* @gfp: Memory allocation flags
|
|
* @nent_p: [out] Number of entries in the scatterlist
|
|
*
|
|
* Returns: A pointer to an initialized scatterlist or %NULL upon failure.
|
|
*/
|
|
struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
|
|
unsigned int *nent_p)
|
|
{
|
|
return sgl_alloc_order(length, 0, false, gfp, nent_p);
|
|
}
|
|
EXPORT_SYMBOL(sgl_alloc);
|
|
|
|
/**
|
|
* sgl_free_n_order - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
* @nents: Maximum number of elements to free
|
|
* @order: Second argument for __free_pages()
|
|
*
|
|
* Notes:
|
|
* - If several scatterlists have been chained and each chain element is
|
|
* freed separately then it's essential to set nents correctly to avoid that a
|
|
* page would get freed twice.
|
|
* - All pages in a chained scatterlist can be freed at once by setting @nents
|
|
* to a high number.
|
|
*/
|
|
void sgl_free_n_order(struct scatterlist *sgl, int nents, int order)
|
|
{
|
|
struct scatterlist *sg;
|
|
struct page *page;
|
|
int i;
|
|
|
|
for_each_sg(sgl, sg, nents, i) {
|
|
if (!sg)
|
|
break;
|
|
page = sg_page(sg);
|
|
if (page)
|
|
__free_pages(page, order);
|
|
}
|
|
kfree(sgl);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free_n_order);
|
|
|
|
/**
|
|
* sgl_free_order - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
* @order: Second argument for __free_pages()
|
|
*/
|
|
void sgl_free_order(struct scatterlist *sgl, int order)
|
|
{
|
|
sgl_free_n_order(sgl, INT_MAX, order);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free_order);
|
|
|
|
/**
|
|
* sgl_free - free a scatterlist and its pages
|
|
* @sgl: Scatterlist with one or more elements
|
|
*/
|
|
void sgl_free(struct scatterlist *sgl)
|
|
{
|
|
sgl_free_order(sgl, 0);
|
|
}
|
|
EXPORT_SYMBOL(sgl_free);
|
|
|
|
#endif /* CONFIG_SGL_ALLOC */
|
|
|
|
void __sg_page_iter_start(struct sg_page_iter *piter,
|
|
struct scatterlist *sglist, unsigned int nents,
|
|
unsigned long pgoffset)
|
|
{
|
|
piter->__pg_advance = 0;
|
|
piter->__nents = nents;
|
|
|
|
piter->sg = sglist;
|
|
piter->sg_pgoffset = pgoffset;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_start);
|
|
|
|
static int sg_page_count(struct scatterlist *sg)
|
|
{
|
|
return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT;
|
|
}
|
|
|
|
bool __sg_page_iter_next(struct sg_page_iter *piter)
|
|
{
|
|
if (!piter->__nents || !piter->sg)
|
|
return false;
|
|
|
|
piter->sg_pgoffset += piter->__pg_advance;
|
|
piter->__pg_advance = 1;
|
|
|
|
while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
|
|
piter->sg_pgoffset -= sg_page_count(piter->sg);
|
|
piter->sg = sg_next(piter->sg);
|
|
if (!--piter->__nents || !piter->sg)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_next);
|
|
|
|
static int sg_dma_page_count(struct scatterlist *sg)
|
|
{
|
|
return PAGE_ALIGN(sg->offset + sg_dma_len(sg)) >> PAGE_SHIFT;
|
|
}
|
|
|
|
bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter)
|
|
{
|
|
struct sg_page_iter *piter = &dma_iter->base;
|
|
|
|
if (!piter->__nents || !piter->sg)
|
|
return false;
|
|
|
|
piter->sg_pgoffset += piter->__pg_advance;
|
|
piter->__pg_advance = 1;
|
|
|
|
while (piter->sg_pgoffset >= sg_dma_page_count(piter->sg)) {
|
|
piter->sg_pgoffset -= sg_dma_page_count(piter->sg);
|
|
piter->sg = sg_next(piter->sg);
|
|
if (!--piter->__nents || !piter->sg)
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(__sg_page_iter_dma_next);
|
|
|
|
/**
|
|
* sg_miter_start - start mapping iteration over a sg list
|
|
* @miter: sg mapping iter to be started
|
|
* @sgl: sg list to iterate over
|
|
* @nents: number of sg entries
|
|
*
|
|
* Description:
|
|
* Starts mapping iterator @miter.
|
|
*
|
|
* Context:
|
|
* Don't care.
|
|
*/
|
|
void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
|
|
unsigned int nents, unsigned int flags)
|
|
{
|
|
memset(miter, 0, sizeof(struct sg_mapping_iter));
|
|
|
|
__sg_page_iter_start(&miter->piter, sgl, nents, 0);
|
|
WARN_ON(!(flags & (SG_MITER_TO_SG | SG_MITER_FROM_SG)));
|
|
miter->__flags = flags;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_start);
|
|
|
|
static bool sg_miter_get_next_page(struct sg_mapping_iter *miter)
|
|
{
|
|
if (!miter->__remaining) {
|
|
struct scatterlist *sg;
|
|
|
|
if (!__sg_page_iter_next(&miter->piter))
|
|
return false;
|
|
|
|
sg = miter->piter.sg;
|
|
|
|
miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset;
|
|
miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT;
|
|
miter->__offset &= PAGE_SIZE - 1;
|
|
miter->__remaining = sg->offset + sg->length -
|
|
(miter->piter.sg_pgoffset << PAGE_SHIFT) -
|
|
miter->__offset;
|
|
miter->__remaining = min_t(unsigned long, miter->__remaining,
|
|
PAGE_SIZE - miter->__offset);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* sg_miter_skip - reposition mapping iterator
|
|
* @miter: sg mapping iter to be skipped
|
|
* @offset: number of bytes to plus the current location
|
|
*
|
|
* Description:
|
|
* Sets the offset of @miter to its current location plus @offset bytes.
|
|
* If mapping iterator @miter has been proceeded by sg_miter_next(), this
|
|
* stops @miter.
|
|
*
|
|
* Context:
|
|
* Don't care if @miter is stopped, or not proceeded yet.
|
|
* Otherwise, preemption disabled if the SG_MITER_ATOMIC is set.
|
|
*
|
|
* Returns:
|
|
* true if @miter contains the valid mapping. false if end of sg
|
|
* list is reached.
|
|
*/
|
|
bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset)
|
|
{
|
|
sg_miter_stop(miter);
|
|
|
|
while (offset) {
|
|
off_t consumed;
|
|
|
|
if (!sg_miter_get_next_page(miter))
|
|
return false;
|
|
|
|
consumed = min_t(off_t, offset, miter->__remaining);
|
|
miter->__offset += consumed;
|
|
miter->__remaining -= consumed;
|
|
offset -= consumed;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_skip);
|
|
|
|
/**
|
|
* sg_miter_next - proceed mapping iterator to the next mapping
|
|
* @miter: sg mapping iter to proceed
|
|
*
|
|
* Description:
|
|
* Proceeds @miter to the next mapping. @miter should have been started
|
|
* using sg_miter_start(). On successful return, @miter->page,
|
|
* @miter->addr and @miter->length point to the current mapping.
|
|
*
|
|
* Context:
|
|
* Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled
|
|
* till @miter is stopped. May sleep if !SG_MITER_ATOMIC.
|
|
*
|
|
* Returns:
|
|
* true if @miter contains the next mapping. false if end of sg
|
|
* list is reached.
|
|
*/
|
|
bool sg_miter_next(struct sg_mapping_iter *miter)
|
|
{
|
|
sg_miter_stop(miter);
|
|
|
|
/*
|
|
* Get to the next page if necessary.
|
|
* __remaining, __offset is adjusted by sg_miter_stop
|
|
*/
|
|
if (!sg_miter_get_next_page(miter))
|
|
return false;
|
|
|
|
miter->page = sg_page_iter_page(&miter->piter);
|
|
miter->consumed = miter->length = miter->__remaining;
|
|
|
|
if (miter->__flags & SG_MITER_ATOMIC)
|
|
miter->addr = kmap_atomic(miter->page) + miter->__offset;
|
|
else
|
|
miter->addr = kmap(miter->page) + miter->__offset;
|
|
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_next);
|
|
|
|
/**
|
|
* sg_miter_stop - stop mapping iteration
|
|
* @miter: sg mapping iter to be stopped
|
|
*
|
|
* Description:
|
|
* Stops mapping iterator @miter. @miter should have been started
|
|
* using sg_miter_start(). A stopped iteration can be resumed by
|
|
* calling sg_miter_next() on it. This is useful when resources (kmap)
|
|
* need to be released during iteration.
|
|
*
|
|
* Context:
|
|
* Preemption disabled if the SG_MITER_ATOMIC is set. Don't care
|
|
* otherwise.
|
|
*/
|
|
void sg_miter_stop(struct sg_mapping_iter *miter)
|
|
{
|
|
WARN_ON(miter->consumed > miter->length);
|
|
|
|
/* drop resources from the last iteration */
|
|
if (miter->addr) {
|
|
miter->__offset += miter->consumed;
|
|
miter->__remaining -= miter->consumed;
|
|
|
|
if ((miter->__flags & SG_MITER_TO_SG) &&
|
|
!PageSlab(miter->page))
|
|
flush_kernel_dcache_page(miter->page);
|
|
|
|
if (miter->__flags & SG_MITER_ATOMIC) {
|
|
WARN_ON_ONCE(preemptible());
|
|
kunmap_atomic(miter->addr);
|
|
} else
|
|
kunmap(miter->page);
|
|
|
|
miter->page = NULL;
|
|
miter->addr = NULL;
|
|
miter->length = 0;
|
|
miter->consumed = 0;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(sg_miter_stop);
|
|
|
|
/**
|
|
* sg_copy_buffer - Copy data between a linear buffer and an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
* @to_buffer: transfer direction (true == from an sg list to a
|
|
* buffer, false == from a buffer to an sg list)
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
|
|
size_t buflen, off_t skip, bool to_buffer)
|
|
{
|
|
unsigned int offset = 0;
|
|
struct sg_mapping_iter miter;
|
|
unsigned int sg_flags = SG_MITER_ATOMIC;
|
|
|
|
if (to_buffer)
|
|
sg_flags |= SG_MITER_FROM_SG;
|
|
else
|
|
sg_flags |= SG_MITER_TO_SG;
|
|
|
|
sg_miter_start(&miter, sgl, nents, sg_flags);
|
|
|
|
if (!sg_miter_skip(&miter, skip))
|
|
return false;
|
|
|
|
while ((offset < buflen) && sg_miter_next(&miter)) {
|
|
unsigned int len;
|
|
|
|
len = min(miter.length, buflen - offset);
|
|
|
|
if (to_buffer)
|
|
memcpy(buf + offset, miter.addr, len);
|
|
else
|
|
memcpy(miter.addr, buf + offset, len);
|
|
|
|
offset += len;
|
|
}
|
|
|
|
sg_miter_stop(&miter);
|
|
|
|
return offset;
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_buffer);
|
|
|
|
/**
|
|
* sg_copy_from_buffer - Copy from a linear buffer to an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, (void *)buf, buflen, 0, false);
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_from_buffer);
|
|
|
|
/**
|
|
* sg_copy_to_buffer - Copy from an SG list to a linear buffer
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy to
|
|
* @buflen: The number of bytes to copy
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, buf, buflen, 0, true);
|
|
}
|
|
EXPORT_SYMBOL(sg_copy_to_buffer);
|
|
|
|
/**
|
|
* sg_pcopy_from_buffer - Copy from a linear buffer to an SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy from
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen, off_t skip)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, (void *)buf, buflen, skip, false);
|
|
}
|
|
EXPORT_SYMBOL(sg_pcopy_from_buffer);
|
|
|
|
/**
|
|
* sg_pcopy_to_buffer - Copy from an SG list to a linear buffer
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buf: Where to copy to
|
|
* @buflen: The number of bytes to copy
|
|
* @skip: Number of bytes to skip before copying
|
|
*
|
|
* Returns the number of copied bytes.
|
|
*
|
|
**/
|
|
size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen, off_t skip)
|
|
{
|
|
return sg_copy_buffer(sgl, nents, buf, buflen, skip, true);
|
|
}
|
|
EXPORT_SYMBOL(sg_pcopy_to_buffer);
|
|
|
|
/**
|
|
* sg_zero_buffer - Zero-out a part of a SG list
|
|
* @sgl: The SG list
|
|
* @nents: Number of SG entries
|
|
* @buflen: The number of bytes to zero out
|
|
* @skip: Number of bytes to skip before zeroing
|
|
*
|
|
* Returns the number of bytes zeroed.
|
|
**/
|
|
size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
size_t buflen, off_t skip)
|
|
{
|
|
unsigned int offset = 0;
|
|
struct sg_mapping_iter miter;
|
|
unsigned int sg_flags = SG_MITER_ATOMIC | SG_MITER_TO_SG;
|
|
|
|
sg_miter_start(&miter, sgl, nents, sg_flags);
|
|
|
|
if (!sg_miter_skip(&miter, skip))
|
|
return false;
|
|
|
|
while (offset < buflen && sg_miter_next(&miter)) {
|
|
unsigned int len;
|
|
|
|
len = min(miter.length, buflen - offset);
|
|
memset(miter.addr, 0, len);
|
|
|
|
offset += len;
|
|
}
|
|
|
|
sg_miter_stop(&miter);
|
|
return offset;
|
|
}
|
|
EXPORT_SYMBOL(sg_zero_buffer);
|