aboutsummaryrefslogtreecommitdiff
path: root/block/bsg-lib.c
blob: a89d801023044aec97869de0b868c707e4aaf222 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  BSG helper library
 *
 *  Copyright (C) 2008   James Smart, Emulex Corporation
 *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
 *  Copyright (C) 2011   Mike Christie
 */
#include <linux/slab.h>
#include <linux/blk-mq.h>
#include <linux/delay.h>
#include <linux/scatterlist.h>
#include <linux/bsg-lib.h>
#include <linux/export.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/sg.h>

#define uptr64(val) ((void __user *)(uintptr_t)(val))

struct bsg_set {
	struct blk_mq_tag_set	tag_set;
	bsg_job_fn		*job_fn;
	bsg_timeout_fn		*timeout_fn;
};

static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
{
	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
		return -EINVAL;
	if (!capable(CAP_SYS_RAWIO))
		return -EPERM;
	return 0;
}

static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
		fmode_t mode)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
	int ret;

	job->request_len = hdr->request_len;
	job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
	if (IS_ERR(job->request))
		return PTR_ERR(job->request);

	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
		job->bidi_rq = blk_get_request(rq->q, REQ_OP_DRV_IN, 0);
		if (IS_ERR(job->bidi_rq)) {
			ret = PTR_ERR(job->bidi_rq);
			goto out;
		}

		ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
				uptr64(hdr->din_xferp), hdr->din_xfer_len,
				GFP_KERNEL);
		if (ret)
			goto out_free_bidi_rq;

		job->bidi_bio = job->bidi_rq->bio;
	} else {
		job->bidi_rq = NULL;
		job->bidi_bio = NULL;
	}

	return 0;

out_free_bidi_rq:
	if (job->bidi_rq)
		blk_put_request(job->bidi_rq);
out:
	kfree(job->request);
	return ret;
}

static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
	int ret = 0;

	/*
	 * The assignments below don't make much sense, but are kept for
	 * bug by bug backwards compatibility:
	 */
	hdr->device_status = job->result & 0xff;
	hdr->transport_status = host_byte(job->result);
	hdr->driver_status = 0;
	hdr->info = 0;
	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
		hdr->info |= SG_INFO_CHECK;
	hdr->response_len = 0;

	if (job->result < 0) {
		/* we're only returning the result field in the reply */
		job->reply_len = sizeof(u32);
		ret = job->result;
	}

	if (job->reply_len && hdr->response) {
		int len = min(hdr->max_response_len, job->reply_len);

		if (copy_to_user(uptr64(hdr->response), job->reply, len))
			ret = -EFAULT;
		else
			hdr->response_len = len;
	}

	/* we assume all request payload was transferred, residual == 0 */
	hdr->dout_resid = 0;

	if (job->bidi_rq) {
		unsigned int rsp_len = job->reply_payload.payload_len;

		if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
			hdr->din_resid = 0;
		else
			hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
	} else {
		hdr->din_resid = 0;
	}

	return ret;
}

static void bsg_transport_free_rq(struct request *rq)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(rq);

	if (job->bidi_rq) {
		blk_rq_unmap_user(job->bidi_bio);
		blk_put_request(job->bidi_rq);
	}

	kfree(job->request);
}

static const struct bsg_ops bsg_transport_ops = {
	.check_proto		= bsg_transport_check_proto,
	.fill_hdr		= bsg_transport_fill_hdr,
	.complete_rq		= bsg_transport_complete_rq,
	.free_rq		= bsg_transport_free_rq,
};

/**
 * bsg_teardown_job - routine to teardown a bsg job
 * @kref: kref inside bsg_job that is to be torn down
 */
static void bsg_teardown_job(struct kref *kref)
{
	struct bsg_job *job = container_of(kref, struct bsg_job, kref);
	struct request *rq = blk_mq_rq_from_pdu(job);

	put_device(job->dev);	/* release reference for the request */

	kfree(job->request_payload.sg_list);
	kfree(job->reply_payload.sg_list);

	blk_mq_end_request(rq, BLK_STS_OK);
}

void bsg_job_put(struct bsg_job *job)
{
	kref_put(&job->kref, bsg_teardown_job);
}
EXPORT_SYMBOL_GPL(bsg_job_put);

int bsg_job_get(struct bsg_job *job)
{
	return kref_get_unless_zero(&job->kref);
}
EXPORT_SYMBOL_GPL(bsg_job_get);

/**
 * bsg_job_done - completion routine for bsg requests
 * @job: bsg_job that is complete
 * @result: job reply result
 * @reply_payload_rcv_len: length of payload recvd
 *
 * The LLD should call this when the bsg job has completed.
 */
void bsg_job_done(struct bsg_job *job, int result,
		  unsigned int reply_payload_rcv_len)
{
	struct request *rq = blk_mq_rq_from_pdu(job);

	job->result = result;
	job->reply_payload_rcv_len = reply_payload_rcv_len;
	if (likely(!blk_should_fake_timeout(rq->q)))
		blk_mq_complete_request(rq);
}
EXPORT_SYMBOL_GPL(bsg_job_done);

/**
 * bsg_complete - softirq done routine for destroying the bsg requests
 * @rq: BSG request that holds the job to be destroyed
 */
static void bsg_complete(struct request *rq)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(rq);

	bsg_job_put(job);
}

static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
{
	size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);

	BUG_ON(!req->nr_phys_segments);

	buf->sg_list = kmalloc(sz, GFP_KERNEL);
	if (!buf->sg_list)
		return -ENOMEM;
	sg_init_table(buf->sg_list, req->nr_phys_segments);
	buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
	buf->payload_len = blk_rq_bytes(req);
	return 0;
}

/**
 * bsg_prepare_job - create the bsg_job structure for the bsg request
 * @dev: device that is being sent the bsg request
 * @req: BSG request that needs a job structure
 */
static bool bsg_prepare_job(struct device *dev, struct request *req)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(req);
	int ret;

	job->timeout = req->timeout;

	if (req->bio) {
		ret = bsg_map_buffer(&job->request_payload, req);
		if (ret)
			goto failjob_rls_job;
	}
	if (job->bidi_rq) {
		ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
		if (ret)
			goto failjob_rls_rqst_payload;
	}
	job->dev = dev;
	/* take a reference for the request */
	get_device(job->dev);
	kref_init(&job->kref);
	return true;

failjob_rls_rqst_payload:
	kfree(job->request_payload.sg_list);
failjob_rls_job:
	job->result = -ENOMEM;
	return false;
}

/**
 * bsg_queue_rq - generic handler for bsg requests
 * @hctx: hardware queue
 * @bd: queue data
 *
 * On error the create_bsg_job function should return a -Exyz error value
 * that will be set to ->result.
 *
 * Drivers/subsys should pass this to the queue init function.
 */
static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
				 const struct blk_mq_queue_data *bd)
{
	struct request_queue *q = hctx->queue;
	struct device *dev = q->queuedata;
	struct request *req = bd->rq;
	struct bsg_set *bset =
		container_of(q->tag_set, struct bsg_set, tag_set);
	blk_status_t sts = BLK_STS_IOERR;
	int ret;

	blk_mq_start_request(req);

	if (!get_device(dev))
		return BLK_STS_IOERR;

	if (!bsg_prepare_job(dev, req))
		goto out;

	ret = bset->job_fn(blk_mq_rq_to_pdu(req));
	if (!ret)
		sts = BLK_STS_OK;

out:
	put_device(dev);
	return sts;
}

/* called right after the request is allocated for the request_queue */
static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
		       unsigned int hctx_idx, unsigned int numa_node)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(req);

	job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
	if (!job->reply)
		return -ENOMEM;
	return 0;
}

/* called right before the request is given to the request_queue user */
static void bsg_initialize_rq(struct request *req)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(req);
	void *reply = job->reply;

	memset(job, 0, sizeof(*job));
	job->reply = reply;
	job->reply_len = SCSI_SENSE_BUFFERSIZE;
	job->dd_data = job + 1;
}

static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
		       unsigned int hctx_idx)
{
	struct bsg_job *job = blk_mq_rq_to_pdu(req);

	kfree(job->reply);
}

void bsg_remove_queue(struct request_queue *q)
{
	if (q) {
		struct bsg_set *bset =
			container_of(q->tag_set, struct bsg_set, tag_set);

		bsg_unregister_queue(q);
		blk_cleanup_queue(q);
		blk_mq_free_tag_set(&bset->tag_set);
		kfree(bset);
	}
}
EXPORT_SYMBOL_GPL(bsg_remove_queue);

static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
{
	struct bsg_set *bset =
		container_of(rq->q->tag_set, struct bsg_set, tag_set);

	if (!bset->timeout_fn)
		return BLK_EH_DONE;
	return bset->timeout_fn(rq);
}

static const struct blk_mq_ops bsg_mq_ops = {
	.queue_rq		= bsg_queue_rq,
	.init_request		= bsg_init_rq,
	.exit_request		= bsg_exit_rq,
	.initialize_rq_fn	= bsg_initialize_rq,
	.complete		= bsg_complete,
	.timeout		= bsg_timeout,
};

/**
 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 * @dev: device to attach bsg device to
 * @name: device to give bsg device
 * @job_fn: bsg job handler
 * @timeout: timeout handler function pointer
 * @dd_job_size: size of LLD data needed for each job
 */
struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
		bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
{
	struct bsg_set *bset;
	struct blk_mq_tag_set *set;
	struct request_queue *q;
	int ret = -ENOMEM;

	bset = kzalloc(sizeof(*bset), GFP_KERNEL);
	if (!bset)
		return ERR_PTR(-ENOMEM);

	bset->job_fn = job_fn;
	bset->timeout_fn = timeout;

	set = &bset->tag_set;
	set->ops = &bsg_mq_ops;
	set->nr_hw_queues = 1;
	set->queue_depth = 128;
	set->numa_node = NUMA_NO_NODE;
	set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
	set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
	if (blk_mq_alloc_tag_set(set))
		goto out_tag_set;

	q = blk_mq_init_queue(set);
	if (IS_ERR(q)) {
		ret = PTR_ERR(q);
		goto out_queue;
	}

	q->queuedata = dev;
	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);

	ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
	if (ret) {
		printk(KERN_ERR "%s: bsg interface failed to "
		       "initialize - register queue\n", dev->kobj.name);
		goto out_cleanup_queue;
	}

	return q;
out_cleanup_queue:
	blk_cleanup_queue(q);
out_queue:
	blk_mq_free_tag_set(set);
out_tag_set:
	kfree(bset);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(bsg_setup_queue);