![Dan Williams](/assets/img/avatar_default.png)
Found-by: Yuri Tikhonov <yur@emcraft.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
323 lines
9.5 KiB
C
323 lines
9.5 KiB
C
/*
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* xor offload engine api
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*
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* Copyright © 2006, Intel Corporation.
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*
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* Dan Williams <dan.j.williams@intel.com>
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*
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* with architecture considerations by:
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* Neil Brown <neilb@suse.de>
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* Jeff Garzik <jeff@garzik.org>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/mm.h>
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#include <linux/dma-mapping.h>
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#include <linux/raid/xor.h>
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#include <linux/async_tx.h>
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/* do_async_xor - dma map the pages and perform the xor with an engine.
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* This routine is marked __always_inline so it can be compiled away
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* when CONFIG_DMA_ENGINE=n
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*/
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static __always_inline struct dma_async_tx_descriptor *
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do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
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unsigned int offset, int src_cnt, size_t len,
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enum async_tx_flags flags,
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struct dma_async_tx_descriptor *depend_tx,
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dma_async_tx_callback cb_fn, void *cb_param)
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{
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struct dma_device *dma = chan->device;
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dma_addr_t *dma_src = (dma_addr_t *) src_list;
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struct dma_async_tx_descriptor *tx = NULL;
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int src_off = 0;
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int i;
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dma_async_tx_callback _cb_fn;
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void *_cb_param;
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enum async_tx_flags async_flags;
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enum dma_ctrl_flags dma_flags;
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int xor_src_cnt;
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dma_addr_t dma_dest;
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dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_FROM_DEVICE);
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for (i = 0; i < src_cnt; i++)
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dma_src[i] = dma_map_page(dma->dev, src_list[i], offset,
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len, DMA_TO_DEVICE);
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while (src_cnt) {
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async_flags = flags;
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dma_flags = 0;
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xor_src_cnt = min(src_cnt, dma->max_xor);
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/* if we are submitting additional xors, leave the chain open,
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* clear the callback parameters, and leave the destination
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* buffer mapped
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*/
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if (src_cnt > xor_src_cnt) {
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async_flags &= ~ASYNC_TX_ACK;
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dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
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_cb_fn = NULL;
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_cb_param = NULL;
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} else {
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_cb_fn = cb_fn;
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_cb_param = cb_param;
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}
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if (_cb_fn)
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dma_flags |= DMA_PREP_INTERRUPT;
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/* Since we have clobbered the src_list we are committed
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* to doing this asynchronously. Drivers force forward progress
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* in case they can not provide a descriptor
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*/
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tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
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xor_src_cnt, len, dma_flags);
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if (unlikely(!tx))
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async_tx_quiesce(&depend_tx);
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/* spin wait for the preceeding transactions to complete */
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while (unlikely(!tx)) {
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dma_async_issue_pending(chan);
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tx = dma->device_prep_dma_xor(chan, dma_dest,
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&dma_src[src_off],
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xor_src_cnt, len,
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dma_flags);
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}
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async_tx_submit(chan, tx, async_flags, depend_tx, _cb_fn,
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_cb_param);
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depend_tx = tx;
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flags |= ASYNC_TX_DEP_ACK;
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if (src_cnt > xor_src_cnt) {
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/* drop completed sources */
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src_cnt -= xor_src_cnt;
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src_off += xor_src_cnt;
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/* use the intermediate result a source */
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dma_src[--src_off] = dma_dest;
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src_cnt++;
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} else
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break;
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}
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return tx;
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}
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static void
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do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
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int src_cnt, size_t len, enum async_tx_flags flags,
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dma_async_tx_callback cb_fn, void *cb_param)
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{
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int i;
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int xor_src_cnt;
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int src_off = 0;
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void *dest_buf;
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void **srcs = (void **) src_list;
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/* reuse the 'src_list' array to convert to buffer pointers */
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for (i = 0; i < src_cnt; i++)
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srcs[i] = page_address(src_list[i]) + offset;
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/* set destination address */
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dest_buf = page_address(dest) + offset;
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if (flags & ASYNC_TX_XOR_ZERO_DST)
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memset(dest_buf, 0, len);
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while (src_cnt > 0) {
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/* process up to 'MAX_XOR_BLOCKS' sources */
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xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
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xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
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/* drop completed sources */
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src_cnt -= xor_src_cnt;
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src_off += xor_src_cnt;
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}
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async_tx_sync_epilog(cb_fn, cb_param);
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}
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/**
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* async_xor - attempt to xor a set of blocks with a dma engine.
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* xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST
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* flag must be set to not include dest data in the calculation. The
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* assumption with dma eninges is that they only use the destination
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* buffer as a source when it is explicity specified in the source list.
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* @dest: destination page
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* @src_list: array of source pages (if the dest is also a source it must be
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* at index zero). The contents of this array may be overwritten.
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* @offset: offset in pages to start transaction
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* @src_cnt: number of source pages
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* @len: length in bytes
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* @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST,
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* ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
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* @depend_tx: xor depends on the result of this transaction.
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* @cb_fn: function to call when the xor completes
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* @cb_param: parameter to pass to the callback routine
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*/
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struct dma_async_tx_descriptor *
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async_xor(struct page *dest, struct page **src_list, unsigned int offset,
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int src_cnt, size_t len, enum async_tx_flags flags,
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struct dma_async_tx_descriptor *depend_tx,
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dma_async_tx_callback cb_fn, void *cb_param)
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{
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struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR,
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&dest, 1, src_list,
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src_cnt, len);
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BUG_ON(src_cnt <= 1);
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if (chan) {
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/* run the xor asynchronously */
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pr_debug("%s (async): len: %zu\n", __func__, len);
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return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
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flags, depend_tx, cb_fn, cb_param);
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} else {
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/* run the xor synchronously */
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pr_debug("%s (sync): len: %zu\n", __func__, len);
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/* in the sync case the dest is an implied source
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* (assumes the dest is the first source)
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*/
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if (flags & ASYNC_TX_XOR_DROP_DST) {
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src_cnt--;
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src_list++;
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}
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/* wait for any prerequisite operations */
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async_tx_quiesce(&depend_tx);
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do_sync_xor(dest, src_list, offset, src_cnt, len,
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flags, cb_fn, cb_param);
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return NULL;
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}
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}
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EXPORT_SYMBOL_GPL(async_xor);
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static int page_is_zero(struct page *p, unsigned int offset, size_t len)
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{
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char *a = page_address(p) + offset;
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return ((*(u32 *) a) == 0 &&
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memcmp(a, a + 4, len - 4) == 0);
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}
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/**
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* async_xor_zero_sum - attempt a xor parity check with a dma engine.
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* @dest: destination page used if the xor is performed synchronously
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* @src_list: array of source pages. The dest page must be listed as a source
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* at index zero. The contents of this array may be overwritten.
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* @offset: offset in pages to start transaction
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* @src_cnt: number of source pages
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* @len: length in bytes
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* @result: 0 if sum == 0 else non-zero
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* @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
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* @depend_tx: xor depends on the result of this transaction.
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* @cb_fn: function to call when the xor completes
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* @cb_param: parameter to pass to the callback routine
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*/
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struct dma_async_tx_descriptor *
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async_xor_zero_sum(struct page *dest, struct page **src_list,
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unsigned int offset, int src_cnt, size_t len,
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u32 *result, enum async_tx_flags flags,
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struct dma_async_tx_descriptor *depend_tx,
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dma_async_tx_callback cb_fn, void *cb_param)
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{
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struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM,
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&dest, 1, src_list,
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src_cnt, len);
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struct dma_device *device = chan ? chan->device : NULL;
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struct dma_async_tx_descriptor *tx = NULL;
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BUG_ON(src_cnt <= 1);
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if (device && src_cnt <= device->max_xor) {
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dma_addr_t *dma_src = (dma_addr_t *) src_list;
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unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0;
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int i;
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pr_debug("%s: (async) len: %zu\n", __func__, len);
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for (i = 0; i < src_cnt; i++)
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dma_src[i] = dma_map_page(device->dev, src_list[i],
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offset, len, DMA_TO_DEVICE);
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tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt,
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len, result,
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dma_prep_flags);
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if (unlikely(!tx)) {
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async_tx_quiesce(&depend_tx);
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while (!tx) {
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dma_async_issue_pending(chan);
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tx = device->device_prep_dma_zero_sum(chan,
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dma_src, src_cnt, len, result,
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dma_prep_flags);
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}
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}
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async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
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} else {
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unsigned long xor_flags = flags;
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pr_debug("%s: (sync) len: %zu\n", __func__, len);
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xor_flags |= ASYNC_TX_XOR_DROP_DST;
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xor_flags &= ~ASYNC_TX_ACK;
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tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags,
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depend_tx, NULL, NULL);
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async_tx_quiesce(&tx);
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*result = page_is_zero(dest, offset, len) ? 0 : 1;
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async_tx_sync_epilog(cb_fn, cb_param);
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}
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return tx;
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}
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EXPORT_SYMBOL_GPL(async_xor_zero_sum);
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static int __init async_xor_init(void)
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{
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#ifdef CONFIG_DMA_ENGINE
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/* To conserve stack space the input src_list (array of page pointers)
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* is reused to hold the array of dma addresses passed to the driver.
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* This conversion is only possible when dma_addr_t is less than the
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* the size of a pointer. HIGHMEM64G is known to violate this
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* assumption.
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*/
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BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *));
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#endif
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return 0;
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}
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static void __exit async_xor_exit(void)
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{
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do { } while (0);
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}
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module_init(async_xor_init);
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module_exit(async_xor_exit);
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MODULE_AUTHOR("Intel Corporation");
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MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
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MODULE_LICENSE("GPL");
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