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v5.9
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * xor offload engine api
  4 *
  5 * Copyright © 2006, Intel Corporation.
  6 *
  7 *      Dan Williams <dan.j.williams@intel.com>
  8 *
  9 *      with architecture considerations by:
 10 *      Neil Brown <neilb@suse.de>
 11 *      Jeff Garzik <jeff@garzik.org>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 12 */
 13#include <linux/kernel.h>
 14#include <linux/interrupt.h>
 15#include <linux/module.h>
 16#include <linux/mm.h>
 17#include <linux/dma-mapping.h>
 18#include <linux/raid/xor.h>
 19#include <linux/async_tx.h>
 20
 21/* do_async_xor - dma map the pages and perform the xor with an engine */
 22static __async_inline struct dma_async_tx_descriptor *
 23do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap,
 
 24	     struct async_submit_ctl *submit)
 25{
 26	struct dma_device *dma = chan->device;
 27	struct dma_async_tx_descriptor *tx = NULL;
 
 
 28	dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 29	void *cb_param_orig = submit->cb_param;
 30	enum async_tx_flags flags_orig = submit->flags;
 31	enum dma_ctrl_flags dma_flags = 0;
 32	int src_cnt = unmap->to_cnt;
 33	int xor_src_cnt;
 34	dma_addr_t dma_dest = unmap->addr[unmap->to_cnt];
 35	dma_addr_t *src_list = unmap->addr;
 36
 37	while (src_cnt) {
 38		dma_addr_t tmp;
 
 
 
 
 
 
 
 
 
 
 
 
 39
 
 40		submit->flags = flags_orig;
 
 41		xor_src_cnt = min(src_cnt, (int)dma->max_xor);
 42		/* if we are submitting additional xors, leave the chain open
 43		 * and clear the callback parameters
 
 44		 */
 45		if (src_cnt > xor_src_cnt) {
 46			submit->flags &= ~ASYNC_TX_ACK;
 47			submit->flags |= ASYNC_TX_FENCE;
 
 48			submit->cb_fn = NULL;
 49			submit->cb_param = NULL;
 50		} else {
 51			submit->cb_fn = cb_fn_orig;
 52			submit->cb_param = cb_param_orig;
 53		}
 54		if (submit->cb_fn)
 55			dma_flags |= DMA_PREP_INTERRUPT;
 56		if (submit->flags & ASYNC_TX_FENCE)
 57			dma_flags |= DMA_PREP_FENCE;
 58
 59		/* Drivers force forward progress in case they can not provide a
 60		 * descriptor
 61		 */
 62		tmp = src_list[0];
 63		if (src_list > unmap->addr)
 64			src_list[0] = dma_dest;
 65		tx = dma->device_prep_dma_xor(chan, dma_dest, src_list,
 66					      xor_src_cnt, unmap->len,
 67					      dma_flags);
 68
 69		if (unlikely(!tx))
 70			async_tx_quiesce(&submit->depend_tx);
 71
 72		/* spin wait for the preceding transactions to complete */
 73		while (unlikely(!tx)) {
 74			dma_async_issue_pending(chan);
 75			tx = dma->device_prep_dma_xor(chan, dma_dest,
 76						      src_list,
 77						      xor_src_cnt, unmap->len,
 78						      dma_flags);
 79		}
 80		src_list[0] = tmp;
 81
 82		dma_set_unmap(tx, unmap);
 83		async_tx_submit(chan, tx, submit);
 84		submit->depend_tx = tx;
 85
 86		if (src_cnt > xor_src_cnt) {
 87			/* drop completed sources */
 88			src_cnt -= xor_src_cnt;
 
 
 89			/* use the intermediate result a source */
 
 90			src_cnt++;
 91			src_list += xor_src_cnt - 1;
 92		} else
 93			break;
 94	}
 95
 96	return tx;
 97}
 98
 99static void
100do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
101	    int src_cnt, size_t len, struct async_submit_ctl *submit)
102{
103	int i;
104	int xor_src_cnt = 0;
105	int src_off = 0;
106	void *dest_buf;
107	void **srcs;
108
109	if (submit->scribble)
110		srcs = submit->scribble;
111	else
112		srcs = (void **) src_list;
113
114	/* convert to buffer pointers */
115	for (i = 0; i < src_cnt; i++)
116		if (src_list[i])
117			srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
118	src_cnt = xor_src_cnt;
119	/* set destination address */
120	dest_buf = page_address(dest) + offset;
121
122	if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
123		memset(dest_buf, 0, len);
124
125	while (src_cnt > 0) {
126		/* process up to 'MAX_XOR_BLOCKS' sources */
127		xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
128		xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
129
130		/* drop completed sources */
131		src_cnt -= xor_src_cnt;
132		src_off += xor_src_cnt;
133	}
134
135	async_tx_sync_epilog(submit);
136}
137
138/**
139 * async_xor - attempt to xor a set of blocks with a dma engine.
140 * @dest: destination page
141 * @src_list: array of source pages
142 * @offset: common src/dst offset to start transaction
143 * @src_cnt: number of source pages
144 * @len: length in bytes
145 * @submit: submission / completion modifiers
146 *
147 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
148 *
149 * xor_blocks always uses the dest as a source so the
150 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
151 * the calculation.  The assumption with dma eninges is that they only
152 * use the destination buffer as a source when it is explicity specified
153 * in the source list.
154 *
155 * src_list note: if the dest is also a source it must be at index zero.
156 * The contents of this array will be overwritten if a scribble region
157 * is not specified.
158 */
159struct dma_async_tx_descriptor *
160async_xor(struct page *dest, struct page **src_list, unsigned int offset,
161	  int src_cnt, size_t len, struct async_submit_ctl *submit)
162{
163	struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
164						      &dest, 1, src_list,
165						      src_cnt, len);
166	struct dma_device *device = chan ? chan->device : NULL;
167	struct dmaengine_unmap_data *unmap = NULL;
168
169	BUG_ON(src_cnt <= 1);
170
171	if (device)
172		unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOWAIT);
173
174	if (unmap && is_dma_xor_aligned(device, offset, 0, len)) {
175		struct dma_async_tx_descriptor *tx;
176		int i, j;
177
 
178		/* run the xor asynchronously */
179		pr_debug("%s (async): len: %zu\n", __func__, len);
180
181		unmap->len = len;
182		for (i = 0, j = 0; i < src_cnt; i++) {
183			if (!src_list[i])
184				continue;
185			unmap->to_cnt++;
186			unmap->addr[j++] = dma_map_page(device->dev, src_list[i],
187							offset, len, DMA_TO_DEVICE);
188		}
189
190		/* map it bidirectional as it may be re-used as a source */
191		unmap->addr[j] = dma_map_page(device->dev, dest, offset, len,
192					      DMA_BIDIRECTIONAL);
193		unmap->bidi_cnt = 1;
194
195		tx = do_async_xor(chan, unmap, submit);
196		dmaengine_unmap_put(unmap);
197		return tx;
198	} else {
199		dmaengine_unmap_put(unmap);
200		/* run the xor synchronously */
201		pr_debug("%s (sync): len: %zu\n", __func__, len);
202		WARN_ONCE(chan, "%s: no space for dma address conversion\n",
203			  __func__);
204
205		/* in the sync case the dest is an implied source
206		 * (assumes the dest is the first source)
207		 */
208		if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
209			src_cnt--;
210			src_list++;
211		}
212
213		/* wait for any prerequisite operations */
214		async_tx_quiesce(&submit->depend_tx);
215
216		do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
217
218		return NULL;
219	}
220}
221EXPORT_SYMBOL_GPL(async_xor);
222
223static int page_is_zero(struct page *p, unsigned int offset, size_t len)
224{
225	return !memchr_inv(page_address(p) + offset, 0, len);
 
 
226}
227
228static inline struct dma_chan *
229xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
230		 struct page **src_list, int src_cnt, size_t len)
231{
232	#ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
233	return NULL;
234	#endif
235	return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
236				     src_cnt, len);
237}
238
239/**
240 * async_xor_val - attempt a xor parity check with a dma engine.
241 * @dest: destination page used if the xor is performed synchronously
242 * @src_list: array of source pages
243 * @offset: offset in pages to start transaction
244 * @src_cnt: number of source pages
245 * @len: length in bytes
246 * @result: 0 if sum == 0 else non-zero
247 * @submit: submission / completion modifiers
248 *
249 * honored flags: ASYNC_TX_ACK
250 *
251 * src_list note: if the dest is also a source it must be at index zero.
252 * The contents of this array will be overwritten if a scribble region
253 * is not specified.
254 */
255struct dma_async_tx_descriptor *
256async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
257	      int src_cnt, size_t len, enum sum_check_flags *result,
258	      struct async_submit_ctl *submit)
259{
260	struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
261	struct dma_device *device = chan ? chan->device : NULL;
262	struct dma_async_tx_descriptor *tx = NULL;
263	struct dmaengine_unmap_data *unmap = NULL;
264
265	BUG_ON(src_cnt <= 1);
266
267	if (device)
268		unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOWAIT);
 
 
269
270	if (unmap && src_cnt <= device->max_xor &&
271	    is_dma_xor_aligned(device, offset, 0, len)) {
272		unsigned long dma_prep_flags = 0;
273		int i;
274
275		pr_debug("%s: (async) len: %zu\n", __func__, len);
276
277		if (submit->cb_fn)
278			dma_prep_flags |= DMA_PREP_INTERRUPT;
279		if (submit->flags & ASYNC_TX_FENCE)
280			dma_prep_flags |= DMA_PREP_FENCE;
 
 
 
281
282		for (i = 0; i < src_cnt; i++) {
283			unmap->addr[i] = dma_map_page(device->dev, src_list[i],
284						      offset, len, DMA_TO_DEVICE);
285			unmap->to_cnt++;
286		}
287		unmap->len = len;
288
289		tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt,
290						     len, result,
291						     dma_prep_flags);
292		if (unlikely(!tx)) {
293			async_tx_quiesce(&submit->depend_tx);
294
295			while (!tx) {
296				dma_async_issue_pending(chan);
297				tx = device->device_prep_dma_xor_val(chan,
298					unmap->addr, src_cnt, len, result,
299					dma_prep_flags);
300			}
301		}
302		dma_set_unmap(tx, unmap);
303		async_tx_submit(chan, tx, submit);
304	} else {
305		enum async_tx_flags flags_orig = submit->flags;
306
307		pr_debug("%s: (sync) len: %zu\n", __func__, len);
308		WARN_ONCE(device && src_cnt <= device->max_xor,
309			  "%s: no space for dma address conversion\n",
310			  __func__);
311
312		submit->flags |= ASYNC_TX_XOR_DROP_DST;
313		submit->flags &= ~ASYNC_TX_ACK;
314
315		tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
316
317		async_tx_quiesce(&tx);
318
319		*result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
320
321		async_tx_sync_epilog(submit);
322		submit->flags = flags_orig;
323	}
324	dmaengine_unmap_put(unmap);
325
326	return tx;
327}
328EXPORT_SYMBOL_GPL(async_xor_val);
329
330MODULE_AUTHOR("Intel Corporation");
331MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
332MODULE_LICENSE("GPL");
v3.1
 
  1/*
  2 * xor offload engine api
  3 *
  4 * Copyright © 2006, Intel Corporation.
  5 *
  6 *      Dan Williams <dan.j.williams@intel.com>
  7 *
  8 *      with architecture considerations by:
  9 *      Neil Brown <neilb@suse.de>
 10 *      Jeff Garzik <jeff@garzik.org>
 11 *
 12 * This program is free software; you can redistribute it and/or modify it
 13 * under the terms and conditions of the GNU General Public License,
 14 * version 2, as published by the Free Software Foundation.
 15 *
 16 * This program is distributed in the hope it will be useful, but WITHOUT
 17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 18 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 19 * more details.
 20 *
 21 * You should have received a copy of the GNU General Public License along with
 22 * this program; if not, write to the Free Software Foundation, Inc.,
 23 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 24 *
 25 */
 26#include <linux/kernel.h>
 27#include <linux/interrupt.h>
 
 28#include <linux/mm.h>
 29#include <linux/dma-mapping.h>
 30#include <linux/raid/xor.h>
 31#include <linux/async_tx.h>
 32
 33/* do_async_xor - dma map the pages and perform the xor with an engine */
 34static __async_inline struct dma_async_tx_descriptor *
 35do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list,
 36	     unsigned int offset, int src_cnt, size_t len, dma_addr_t *dma_src,
 37	     struct async_submit_ctl *submit)
 38{
 39	struct dma_device *dma = chan->device;
 40	struct dma_async_tx_descriptor *tx = NULL;
 41	int src_off = 0;
 42	int i;
 43	dma_async_tx_callback cb_fn_orig = submit->cb_fn;
 44	void *cb_param_orig = submit->cb_param;
 45	enum async_tx_flags flags_orig = submit->flags;
 46	enum dma_ctrl_flags dma_flags;
 47	int xor_src_cnt = 0;
 48	dma_addr_t dma_dest;
 
 
 49
 50	/* map the dest bidrectional in case it is re-used as a source */
 51	dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL);
 52	for (i = 0; i < src_cnt; i++) {
 53		/* only map the dest once */
 54		if (!src_list[i])
 55			continue;
 56		if (unlikely(src_list[i] == dest)) {
 57			dma_src[xor_src_cnt++] = dma_dest;
 58			continue;
 59		}
 60		dma_src[xor_src_cnt++] = dma_map_page(dma->dev, src_list[i], offset,
 61						      len, DMA_TO_DEVICE);
 62	}
 63	src_cnt = xor_src_cnt;
 64
 65	while (src_cnt) {
 66		submit->flags = flags_orig;
 67		dma_flags = 0;
 68		xor_src_cnt = min(src_cnt, (int)dma->max_xor);
 69		/* if we are submitting additional xors, leave the chain open,
 70		 * clear the callback parameters, and leave the destination
 71		 * buffer mapped
 72		 */
 73		if (src_cnt > xor_src_cnt) {
 74			submit->flags &= ~ASYNC_TX_ACK;
 75			submit->flags |= ASYNC_TX_FENCE;
 76			dma_flags = DMA_COMPL_SKIP_DEST_UNMAP;
 77			submit->cb_fn = NULL;
 78			submit->cb_param = NULL;
 79		} else {
 80			submit->cb_fn = cb_fn_orig;
 81			submit->cb_param = cb_param_orig;
 82		}
 83		if (submit->cb_fn)
 84			dma_flags |= DMA_PREP_INTERRUPT;
 85		if (submit->flags & ASYNC_TX_FENCE)
 86			dma_flags |= DMA_PREP_FENCE;
 87		/* Since we have clobbered the src_list we are committed
 88		 * to doing this asynchronously.  Drivers force forward progress
 89		 * in case they can not provide a descriptor
 90		 */
 91		tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off],
 92					      xor_src_cnt, len, dma_flags);
 
 
 
 
 93
 94		if (unlikely(!tx))
 95			async_tx_quiesce(&submit->depend_tx);
 96
 97		/* spin wait for the preceding transactions to complete */
 98		while (unlikely(!tx)) {
 99			dma_async_issue_pending(chan);
100			tx = dma->device_prep_dma_xor(chan, dma_dest,
101						      &dma_src[src_off],
102						      xor_src_cnt, len,
103						      dma_flags);
104		}
 
105
 
106		async_tx_submit(chan, tx, submit);
107		submit->depend_tx = tx;
108
109		if (src_cnt > xor_src_cnt) {
110			/* drop completed sources */
111			src_cnt -= xor_src_cnt;
112			src_off += xor_src_cnt;
113
114			/* use the intermediate result a source */
115			dma_src[--src_off] = dma_dest;
116			src_cnt++;
 
117		} else
118			break;
119	}
120
121	return tx;
122}
123
124static void
125do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
126	    int src_cnt, size_t len, struct async_submit_ctl *submit)
127{
128	int i;
129	int xor_src_cnt = 0;
130	int src_off = 0;
131	void *dest_buf;
132	void **srcs;
133
134	if (submit->scribble)
135		srcs = submit->scribble;
136	else
137		srcs = (void **) src_list;
138
139	/* convert to buffer pointers */
140	for (i = 0; i < src_cnt; i++)
141		if (src_list[i])
142			srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
143	src_cnt = xor_src_cnt;
144	/* set destination address */
145	dest_buf = page_address(dest) + offset;
146
147	if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
148		memset(dest_buf, 0, len);
149
150	while (src_cnt > 0) {
151		/* process up to 'MAX_XOR_BLOCKS' sources */
152		xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
153		xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]);
154
155		/* drop completed sources */
156		src_cnt -= xor_src_cnt;
157		src_off += xor_src_cnt;
158	}
159
160	async_tx_sync_epilog(submit);
161}
162
163/**
164 * async_xor - attempt to xor a set of blocks with a dma engine.
165 * @dest: destination page
166 * @src_list: array of source pages
167 * @offset: common src/dst offset to start transaction
168 * @src_cnt: number of source pages
169 * @len: length in bytes
170 * @submit: submission / completion modifiers
171 *
172 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST
173 *
174 * xor_blocks always uses the dest as a source so the
175 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in
176 * the calculation.  The assumption with dma eninges is that they only
177 * use the destination buffer as a source when it is explicity specified
178 * in the source list.
179 *
180 * src_list note: if the dest is also a source it must be at index zero.
181 * The contents of this array will be overwritten if a scribble region
182 * is not specified.
183 */
184struct dma_async_tx_descriptor *
185async_xor(struct page *dest, struct page **src_list, unsigned int offset,
186	  int src_cnt, size_t len, struct async_submit_ctl *submit)
187{
188	struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR,
189						      &dest, 1, src_list,
190						      src_cnt, len);
191	dma_addr_t *dma_src = NULL;
 
192
193	BUG_ON(src_cnt <= 1);
194
195	if (submit->scribble)
196		dma_src = submit->scribble;
197	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
198		dma_src = (dma_addr_t *) src_list;
 
 
199
200	if (dma_src && chan && is_dma_xor_aligned(chan->device, offset, 0, len)) {
201		/* run the xor asynchronously */
202		pr_debug("%s (async): len: %zu\n", __func__, len);
203
204		return do_async_xor(chan, dest, src_list, offset, src_cnt, len,
205				    dma_src, submit);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
206	} else {
 
207		/* run the xor synchronously */
208		pr_debug("%s (sync): len: %zu\n", __func__, len);
209		WARN_ONCE(chan, "%s: no space for dma address conversion\n",
210			  __func__);
211
212		/* in the sync case the dest is an implied source
213		 * (assumes the dest is the first source)
214		 */
215		if (submit->flags & ASYNC_TX_XOR_DROP_DST) {
216			src_cnt--;
217			src_list++;
218		}
219
220		/* wait for any prerequisite operations */
221		async_tx_quiesce(&submit->depend_tx);
222
223		do_sync_xor(dest, src_list, offset, src_cnt, len, submit);
224
225		return NULL;
226	}
227}
228EXPORT_SYMBOL_GPL(async_xor);
229
230static int page_is_zero(struct page *p, unsigned int offset, size_t len)
231{
232	char *a = page_address(p) + offset;
233	return ((*(u32 *) a) == 0 &&
234		memcmp(a, a + 4, len - 4) == 0);
235}
236
237static inline struct dma_chan *
238xor_val_chan(struct async_submit_ctl *submit, struct page *dest,
239		 struct page **src_list, int src_cnt, size_t len)
240{
241	#ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA
242	return NULL;
243	#endif
244	return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list,
245				     src_cnt, len);
246}
247
248/**
249 * async_xor_val - attempt a xor parity check with a dma engine.
250 * @dest: destination page used if the xor is performed synchronously
251 * @src_list: array of source pages
252 * @offset: offset in pages to start transaction
253 * @src_cnt: number of source pages
254 * @len: length in bytes
255 * @result: 0 if sum == 0 else non-zero
256 * @submit: submission / completion modifiers
257 *
258 * honored flags: ASYNC_TX_ACK
259 *
260 * src_list note: if the dest is also a source it must be at index zero.
261 * The contents of this array will be overwritten if a scribble region
262 * is not specified.
263 */
264struct dma_async_tx_descriptor *
265async_xor_val(struct page *dest, struct page **src_list, unsigned int offset,
266	      int src_cnt, size_t len, enum sum_check_flags *result,
267	      struct async_submit_ctl *submit)
268{
269	struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len);
270	struct dma_device *device = chan ? chan->device : NULL;
271	struct dma_async_tx_descriptor *tx = NULL;
272	dma_addr_t *dma_src = NULL;
273
274	BUG_ON(src_cnt <= 1);
275
276	if (submit->scribble)
277		dma_src = submit->scribble;
278	else if (sizeof(dma_addr_t) <= sizeof(struct page *))
279		dma_src = (dma_addr_t *) src_list;
280
281	if (dma_src && device && src_cnt <= device->max_xor &&
282	    is_dma_xor_aligned(device, offset, 0, len)) {
283		unsigned long dma_prep_flags = 0;
284		int i;
285
286		pr_debug("%s: (async) len: %zu\n", __func__, len);
287
288		if (submit->cb_fn)
289			dma_prep_flags |= DMA_PREP_INTERRUPT;
290		if (submit->flags & ASYNC_TX_FENCE)
291			dma_prep_flags |= DMA_PREP_FENCE;
292		for (i = 0; i < src_cnt; i++)
293			dma_src[i] = dma_map_page(device->dev, src_list[i],
294						  offset, len, DMA_TO_DEVICE);
295
296		tx = device->device_prep_dma_xor_val(chan, dma_src, src_cnt,
 
 
 
 
 
 
 
297						     len, result,
298						     dma_prep_flags);
299		if (unlikely(!tx)) {
300			async_tx_quiesce(&submit->depend_tx);
301
302			while (!tx) {
303				dma_async_issue_pending(chan);
304				tx = device->device_prep_dma_xor_val(chan,
305					dma_src, src_cnt, len, result,
306					dma_prep_flags);
307			}
308		}
309
310		async_tx_submit(chan, tx, submit);
311	} else {
312		enum async_tx_flags flags_orig = submit->flags;
313
314		pr_debug("%s: (sync) len: %zu\n", __func__, len);
315		WARN_ONCE(device && src_cnt <= device->max_xor,
316			  "%s: no space for dma address conversion\n",
317			  __func__);
318
319		submit->flags |= ASYNC_TX_XOR_DROP_DST;
320		submit->flags &= ~ASYNC_TX_ACK;
321
322		tx = async_xor(dest, src_list, offset, src_cnt, len, submit);
323
324		async_tx_quiesce(&tx);
325
326		*result = !page_is_zero(dest, offset, len) << SUM_CHECK_P;
327
328		async_tx_sync_epilog(submit);
329		submit->flags = flags_orig;
330	}
 
331
332	return tx;
333}
334EXPORT_SYMBOL_GPL(async_xor_val);
335
336MODULE_AUTHOR("Intel Corporation");
337MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api");
338MODULE_LICENSE("GPL");