1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  BSG helper library
4 *
5 *  Copyright (C) 2008   James Smart, Emulex Corporation
6 *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
7 *  Copyright (C) 2011   Mike Christie
8 */
9#include <linux/bsg.h>
10#include <linux/slab.h>
11#include <linux/blk-mq.h>
12#include <linux/delay.h>
13#include <linux/scatterlist.h>
14#include <linux/bsg-lib.h>
15#include <linux/export.h>
16#include <scsi/scsi_cmnd.h>
17#include <scsi/sg.h>
18
19#define uptr64(val) ((void __user *)(uintptr_t)(val))
20
21struct bsg_set {
22	struct blk_mq_tag_set	tag_set;
23	struct bsg_device	*bd;
24	bsg_job_fn		*job_fn;
25	bsg_timeout_fn		*timeout_fn;
26};
27
28static int bsg_transport_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
29		bool open_for_write, unsigned int timeout)
30{
31	struct bsg_job *job;
32	struct request *rq;
33	struct bio *bio;
34	void *reply;
35	int ret;
36
37	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
38	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
39		return -EINVAL;
40	if (!capable(CAP_SYS_RAWIO))
41		return -EPERM;
42
43	rq = blk_mq_alloc_request(q, hdr->dout_xfer_len ?
44			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
45	if (IS_ERR(rq))
46		return PTR_ERR(rq);
47	rq->timeout = timeout;
48
49	job = blk_mq_rq_to_pdu(rq);
50	reply = job->reply;
51	memset(job, 0, sizeof(*job));
52	job->reply = reply;
53	job->reply_len = SCSI_SENSE_BUFFERSIZE;
54	job->dd_data = job + 1;
55
56	job->request_len = hdr->request_len;
57	job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
58	if (IS_ERR(job->request)) {
59		ret = PTR_ERR(job->request);
60		goto out_free_rq;
61	}
62
63	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
64		job->bidi_rq = blk_mq_alloc_request(rq->q, REQ_OP_DRV_IN, 0);
65		if (IS_ERR(job->bidi_rq)) {
66			ret = PTR_ERR(job->bidi_rq);
67			goto out_free_job_request;
68		}
69
70		ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
71				uptr64(hdr->din_xferp), hdr->din_xfer_len,
72				GFP_KERNEL);
73		if (ret)
74			goto out_free_bidi_rq;
75
76		job->bidi_bio = job->bidi_rq->bio;
77	} else {
78		job->bidi_rq = NULL;
79		job->bidi_bio = NULL;
80	}
81
82	ret = 0;
83	if (hdr->dout_xfer_len) {
84		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
85				hdr->dout_xfer_len, GFP_KERNEL);
86	} else if (hdr->din_xfer_len) {
87		ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
88				hdr->din_xfer_len, GFP_KERNEL);
89	}
90
91	if (ret)
92		goto out_unmap_bidi_rq;
93
94	bio = rq->bio;
95	blk_execute_rq(rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
96
97	/*
98	 * The assignments below don't make much sense, but are kept for
99	 * bug by bug backwards compatibility:
100	 */
101	hdr->device_status = job->result & 0xff;
102	hdr->transport_status = host_byte(job->result);
103	hdr->driver_status = 0;
104	hdr->info = 0;
105	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
106		hdr->info |= SG_INFO_CHECK;
107	hdr->response_len = 0;
108
109	if (job->result < 0) {
110		/* we're only returning the result field in the reply */
111		job->reply_len = sizeof(u32);
112		ret = job->result;
113	}
114
115	if (job->reply_len && hdr->response) {
116		int len = min(hdr->max_response_len, job->reply_len);
117
118		if (copy_to_user(uptr64(hdr->response), job->reply, len))
119			ret = -EFAULT;
120		else
121			hdr->response_len = len;
122	}
123
124	/* we assume all request payload was transferred, residual == 0 */
125	hdr->dout_resid = 0;
126
127	if (job->bidi_rq) {
128		unsigned int rsp_len = job->reply_payload.payload_len;
129
130		if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
131			hdr->din_resid = 0;
132		else
133			hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
134	} else {
135		hdr->din_resid = 0;
136	}
137
138	blk_rq_unmap_user(bio);
139out_unmap_bidi_rq:
140	if (job->bidi_rq)
141		blk_rq_unmap_user(job->bidi_bio);
142out_free_bidi_rq:
143	if (job->bidi_rq)
144		blk_mq_free_request(job->bidi_rq);
145out_free_job_request:
146	kfree(job->request);
147out_free_rq:
148	blk_mq_free_request(rq);
149	return ret;
150}
151
152/**
153 * bsg_teardown_job - routine to teardown a bsg job
154 * @kref: kref inside bsg_job that is to be torn down
155 */
156static void bsg_teardown_job(struct kref *kref)
157{
158	struct bsg_job *job = container_of(kref, struct bsg_job, kref);
159	struct request *rq = blk_mq_rq_from_pdu(job);
160
161	put_device(job->dev);	/* release reference for the request */
162
163	kfree(job->request_payload.sg_list);
164	kfree(job->reply_payload.sg_list);
165
166	blk_mq_end_request(rq, BLK_STS_OK);
167}
168
169void bsg_job_put(struct bsg_job *job)
170{
171	kref_put(&job->kref, bsg_teardown_job);
172}
173EXPORT_SYMBOL_GPL(bsg_job_put);
174
175int bsg_job_get(struct bsg_job *job)
176{
177	return kref_get_unless_zero(&job->kref);
178}
179EXPORT_SYMBOL_GPL(bsg_job_get);
180
181/**
182 * bsg_job_done - completion routine for bsg requests
183 * @job: bsg_job that is complete
184 * @result: job reply result
185 * @reply_payload_rcv_len: length of payload recvd
186 *
187 * The LLD should call this when the bsg job has completed.
188 */
189void bsg_job_done(struct bsg_job *job, int result,
190		  unsigned int reply_payload_rcv_len)
191{
192	struct request *rq = blk_mq_rq_from_pdu(job);
193
194	job->result = result;
195	job->reply_payload_rcv_len = reply_payload_rcv_len;
196	if (likely(!blk_should_fake_timeout(rq->q)))
197		blk_mq_complete_request(rq);
198}
199EXPORT_SYMBOL_GPL(bsg_job_done);
200
201/**
202 * bsg_complete - softirq done routine for destroying the bsg requests
203 * @rq: BSG request that holds the job to be destroyed
204 */
205static void bsg_complete(struct request *rq)
206{
207	struct bsg_job *job = blk_mq_rq_to_pdu(rq);
208
209	bsg_job_put(job);
210}
211
212static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
213{
214	size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
215
216	BUG_ON(!req->nr_phys_segments);
217
218	buf->sg_list = kmalloc(sz, GFP_KERNEL);
219	if (!buf->sg_list)
220		return -ENOMEM;
221	sg_init_table(buf->sg_list, req->nr_phys_segments);
222	buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
223	buf->payload_len = blk_rq_bytes(req);
224	return 0;
225}
226
227/**
228 * bsg_prepare_job - create the bsg_job structure for the bsg request
229 * @dev: device that is being sent the bsg request
230 * @req: BSG request that needs a job structure
231 */
232static bool bsg_prepare_job(struct device *dev, struct request *req)
233{
234	struct bsg_job *job = blk_mq_rq_to_pdu(req);
235	int ret;
236
237	job->timeout = req->timeout;
238
239	if (req->bio) {
240		ret = bsg_map_buffer(&job->request_payload, req);
241		if (ret)
242			goto failjob_rls_job;
243	}
244	if (job->bidi_rq) {
245		ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
246		if (ret)
247			goto failjob_rls_rqst_payload;
248	}
249	job->dev = dev;
250	/* take a reference for the request */
251	get_device(job->dev);
252	kref_init(&job->kref);
253	return true;
254
255failjob_rls_rqst_payload:
256	kfree(job->request_payload.sg_list);
257failjob_rls_job:
258	job->result = -ENOMEM;
259	return false;
260}
261
262/**
263 * bsg_queue_rq - generic handler for bsg requests
264 * @hctx: hardware queue
265 * @bd: queue data
266 *
267 * On error the create_bsg_job function should return a -Exyz error value
268 * that will be set to ->result.
269 *
270 * Drivers/subsys should pass this to the queue init function.
271 */
272static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
273				 const struct blk_mq_queue_data *bd)
274{
275	struct request_queue *q = hctx->queue;
276	struct device *dev = q->queuedata;
277	struct request *req = bd->rq;
278	struct bsg_set *bset =
279		container_of(q->tag_set, struct bsg_set, tag_set);
280	blk_status_t sts = BLK_STS_IOERR;
281	int ret;
282
283	blk_mq_start_request(req);
284
285	if (!get_device(dev))
286		return BLK_STS_IOERR;
287
288	if (!bsg_prepare_job(dev, req))
289		goto out;
290
291	ret = bset->job_fn(blk_mq_rq_to_pdu(req));
292	if (!ret)
293		sts = BLK_STS_OK;
294
295out:
296	put_device(dev);
297	return sts;
298}
299
300/* called right after the request is allocated for the request_queue */
301static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
302		       unsigned int hctx_idx, unsigned int numa_node)
303{
304	struct bsg_job *job = blk_mq_rq_to_pdu(req);
305
306	job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
307	if (!job->reply)
308		return -ENOMEM;
309	return 0;
310}
311
312static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
313		       unsigned int hctx_idx)
314{
315	struct bsg_job *job = blk_mq_rq_to_pdu(req);
316
317	kfree(job->reply);
318}
319
320void bsg_remove_queue(struct request_queue *q)
321{
322	if (q) {
323		struct bsg_set *bset =
324			container_of(q->tag_set, struct bsg_set, tag_set);
325
326		bsg_unregister_queue(bset->bd);
327		blk_mq_destroy_queue(q);
328		blk_put_queue(q);
329		blk_mq_free_tag_set(&bset->tag_set);
330		kfree(bset);
331	}
332}
333EXPORT_SYMBOL_GPL(bsg_remove_queue);
334
335static enum blk_eh_timer_return bsg_timeout(struct request *rq)
336{
337	struct bsg_set *bset =
338		container_of(rq->q->tag_set, struct bsg_set, tag_set);
339
340	if (!bset->timeout_fn)
341		return BLK_EH_DONE;
342	return bset->timeout_fn(rq);
343}
344
345static const struct blk_mq_ops bsg_mq_ops = {
346	.queue_rq		= bsg_queue_rq,
347	.init_request		= bsg_init_rq,
348	.exit_request		= bsg_exit_rq,
349	.complete		= bsg_complete,
350	.timeout		= bsg_timeout,
351};
352
353/**
354 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
355 * @dev: device to attach bsg device to
356 * @name: device to give bsg device
357 * @job_fn: bsg job handler
358 * @timeout: timeout handler function pointer
359 * @dd_job_size: size of LLD data needed for each job
360 */
361struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
362		bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
363{
364	struct bsg_set *bset;
365	struct blk_mq_tag_set *set;
366	struct request_queue *q;
367	int ret = -ENOMEM;
368
369	bset = kzalloc(sizeof(*bset), GFP_KERNEL);
370	if (!bset)
371		return ERR_PTR(-ENOMEM);
372
373	bset->job_fn = job_fn;
374	bset->timeout_fn = timeout;
375
376	set = &bset->tag_set;
377	set->ops = &bsg_mq_ops;
378	set->nr_hw_queues = 1;
379	set->queue_depth = 128;
380	set->numa_node = NUMA_NO_NODE;
381	set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
382	set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
383	if (blk_mq_alloc_tag_set(set))
384		goto out_tag_set;
385
386	q = blk_mq_alloc_queue(set, NULL, NULL);
387	if (IS_ERR(q)) {
388		ret = PTR_ERR(q);
389		goto out_queue;
390	}
391
392	q->queuedata = dev;
393	blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
394
395	bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
396	if (IS_ERR(bset->bd)) {
397		ret = PTR_ERR(bset->bd);
398		goto out_cleanup_queue;
399	}
400
401	return q;
402out_cleanup_queue:
403	blk_mq_destroy_queue(q);
404	blk_put_queue(q);
405out_queue:
406	blk_mq_free_tag_set(set);
407out_tag_set:
408	kfree(bset);
409	return ERR_PTR(ret);
410}
411EXPORT_SYMBOL_GPL(bsg_setup_queue);
412