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Linux/block/bsg-lib.c

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  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 
 21 struct 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 
 28 static int bsg_transport_sg_io_fn(struct request_queue *q, struct sg_io_v4 *hdr,
 29                 fmode_t mode, 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(NULL, 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);
139 out_unmap_bidi_rq:
140         if (job->bidi_rq)
141                 blk_rq_unmap_user(job->bidi_bio);
142 out_free_bidi_rq:
143         if (job->bidi_rq)
144                 blk_mq_free_request(job->bidi_rq);
145 out_free_job_request:
146         kfree(job->request);
147 out_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  */
156 static 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 
169 void bsg_job_put(struct bsg_job *job)
170 {
171         kref_put(&job->kref, bsg_teardown_job);
172 }
173 EXPORT_SYMBOL_GPL(bsg_job_put);
174 
175 int bsg_job_get(struct bsg_job *job)
176 {
177         return kref_get_unless_zero(&job->kref);
178 }
179 EXPORT_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  */
189 void 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 }
199 EXPORT_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  */
205 static 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 
212 static 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  */
232 static 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 
255 failjob_rls_rqst_payload:
256         kfree(job->request_payload.sg_list);
257 failjob_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  */
272 static 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 
295 out:
296         put_device(dev);
297         return sts;
298 }
299 
300 /* called right after the request is allocated for the request_queue */
301 static 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 
312 static 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 
320 void 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_cleanup_queue(q);
328                 blk_mq_free_tag_set(&bset->tag_set);
329                 kfree(bset);
330         }
331 }
332 EXPORT_SYMBOL_GPL(bsg_remove_queue);
333 
334 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
335 {
336         struct bsg_set *bset =
337                 container_of(rq->q->tag_set, struct bsg_set, tag_set);
338 
339         if (!bset->timeout_fn)
340                 return BLK_EH_DONE;
341         return bset->timeout_fn(rq);
342 }
343 
344 static const struct blk_mq_ops bsg_mq_ops = {
345         .queue_rq               = bsg_queue_rq,
346         .init_request           = bsg_init_rq,
347         .exit_request           = bsg_exit_rq,
348         .complete               = bsg_complete,
349         .timeout                = bsg_timeout,
350 };
351 
352 /**
353  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
354  * @dev: device to attach bsg device to
355  * @name: device to give bsg device
356  * @job_fn: bsg job handler
357  * @timeout: timeout handler function pointer
358  * @dd_job_size: size of LLD data needed for each job
359  */
360 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
361                 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
362 {
363         struct bsg_set *bset;
364         struct blk_mq_tag_set *set;
365         struct request_queue *q;
366         int ret = -ENOMEM;
367 
368         bset = kzalloc(sizeof(*bset), GFP_KERNEL);
369         if (!bset)
370                 return ERR_PTR(-ENOMEM);
371 
372         bset->job_fn = job_fn;
373         bset->timeout_fn = timeout;
374 
375         set = &bset->tag_set;
376         set->ops = &bsg_mq_ops;
377         set->nr_hw_queues = 1;
378         set->queue_depth = 128;
379         set->numa_node = NUMA_NO_NODE;
380         set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
381         set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
382         if (blk_mq_alloc_tag_set(set))
383                 goto out_tag_set;
384 
385         q = blk_mq_init_queue(set);
386         if (IS_ERR(q)) {
387                 ret = PTR_ERR(q);
388                 goto out_queue;
389         }
390 
391         q->queuedata = dev;
392         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
393 
394         bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
395         if (IS_ERR(bset->bd)) {
396                 ret = PTR_ERR(bset->bd);
397                 goto out_cleanup_queue;
398         }
399 
400         return q;
401 out_cleanup_queue:
402         blk_cleanup_queue(q);
403 out_queue:
404         blk_mq_free_tag_set(set);
405 out_tag_set:
406         kfree(bset);
407         return ERR_PTR(ret);
408 }
409 EXPORT_SYMBOL_GPL(bsg_setup_queue);
410 

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