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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/slab.h>
 10 #include <linux/blk-mq.h>
 11 #include <linux/delay.h>
 12 #include <linux/scatterlist.h>
 13 #include <linux/bsg-lib.h>
 14 #include <linux/export.h>
 15 #include <scsi/scsi_cmnd.h>
 16 #include <scsi/sg.h>
 17 
 18 #define uptr64(val) ((void __user *)(uintptr_t)(val))
 19 
 20 struct bsg_set {
 21         struct blk_mq_tag_set   tag_set;
 22         bsg_job_fn              *job_fn;
 23         bsg_timeout_fn          *timeout_fn;
 24 };
 25 
 26 static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
 27 {
 28         if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
 29             hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
 30                 return -EINVAL;
 31         if (!capable(CAP_SYS_RAWIO))
 32                 return -EPERM;
 33         return 0;
 34 }
 35 
 36 static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
 37                 fmode_t mode)
 38 {
 39         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 40         int ret;
 41 
 42         job->request_len = hdr->request_len;
 43         job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
 44         if (IS_ERR(job->request))
 45                 return PTR_ERR(job->request);
 46 
 47         if (hdr->dout_xfer_len && hdr->din_xfer_len) {
 48                 job->bidi_rq = blk_get_request(rq->q, REQ_OP_SCSI_IN, 0);
 49                 if (IS_ERR(job->bidi_rq)) {
 50                         ret = PTR_ERR(job->bidi_rq);
 51                         goto out;
 52                 }
 53 
 54                 ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
 55                                 uptr64(hdr->din_xferp), hdr->din_xfer_len,
 56                                 GFP_KERNEL);
 57                 if (ret)
 58                         goto out_free_bidi_rq;
 59 
 60                 job->bidi_bio = job->bidi_rq->bio;
 61         } else {
 62                 job->bidi_rq = NULL;
 63                 job->bidi_bio = NULL;
 64         }
 65 
 66         return 0;
 67 
 68 out_free_bidi_rq:
 69         if (job->bidi_rq)
 70                 blk_put_request(job->bidi_rq);
 71 out:
 72         kfree(job->request);
 73         return ret;
 74 }
 75 
 76 static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
 77 {
 78         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 79         int ret = 0;
 80 
 81         /*
 82          * The assignments below don't make much sense, but are kept for
 83          * bug by bug backwards compatibility:
 84          */
 85         hdr->device_status = job->result & 0xff;
 86         hdr->transport_status = host_byte(job->result);
 87         hdr->driver_status = driver_byte(job->result);
 88         hdr->info = 0;
 89         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
 90                 hdr->info |= SG_INFO_CHECK;
 91         hdr->response_len = 0;
 92 
 93         if (job->result < 0) {
 94                 /* we're only returning the result field in the reply */
 95                 job->reply_len = sizeof(u32);
 96                 ret = job->result;
 97         }
 98 
 99         if (job->reply_len && hdr->response) {
100                 int len = min(hdr->max_response_len, job->reply_len);
101 
102                 if (copy_to_user(uptr64(hdr->response), job->reply, len))
103                         ret = -EFAULT;
104                 else
105                         hdr->response_len = len;
106         }
107 
108         /* we assume all request payload was transferred, residual == 0 */
109         hdr->dout_resid = 0;
110 
111         if (job->bidi_rq) {
112                 unsigned int rsp_len = job->reply_payload.payload_len;
113 
114                 if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
115                         hdr->din_resid = 0;
116                 else
117                         hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
118         } else {
119                 hdr->din_resid = 0;
120         }
121 
122         return ret;
123 }
124 
125 static void bsg_transport_free_rq(struct request *rq)
126 {
127         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
128 
129         if (job->bidi_rq) {
130                 blk_rq_unmap_user(job->bidi_bio);
131                 blk_put_request(job->bidi_rq);
132         }
133 
134         kfree(job->request);
135 }
136 
137 static const struct bsg_ops bsg_transport_ops = {
138         .check_proto            = bsg_transport_check_proto,
139         .fill_hdr               = bsg_transport_fill_hdr,
140         .complete_rq            = bsg_transport_complete_rq,
141         .free_rq                = bsg_transport_free_rq,
142 };
143 
144 /**
145  * bsg_teardown_job - routine to teardown a bsg job
146  * @kref: kref inside bsg_job that is to be torn down
147  */
148 static void bsg_teardown_job(struct kref *kref)
149 {
150         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
151         struct request *rq = blk_mq_rq_from_pdu(job);
152 
153         put_device(job->dev);   /* release reference for the request */
154 
155         kfree(job->request_payload.sg_list);
156         kfree(job->reply_payload.sg_list);
157 
158         blk_mq_end_request(rq, BLK_STS_OK);
159 }
160 
161 void bsg_job_put(struct bsg_job *job)
162 {
163         kref_put(&job->kref, bsg_teardown_job);
164 }
165 EXPORT_SYMBOL_GPL(bsg_job_put);
166 
167 int bsg_job_get(struct bsg_job *job)
168 {
169         return kref_get_unless_zero(&job->kref);
170 }
171 EXPORT_SYMBOL_GPL(bsg_job_get);
172 
173 /**
174  * bsg_job_done - completion routine for bsg requests
175  * @job: bsg_job that is complete
176  * @result: job reply result
177  * @reply_payload_rcv_len: length of payload recvd
178  *
179  * The LLD should call this when the bsg job has completed.
180  */
181 void bsg_job_done(struct bsg_job *job, int result,
182                   unsigned int reply_payload_rcv_len)
183 {
184         job->result = result;
185         job->reply_payload_rcv_len = reply_payload_rcv_len;
186         blk_mq_complete_request(blk_mq_rq_from_pdu(job));
187 }
188 EXPORT_SYMBOL_GPL(bsg_job_done);
189 
190 /**
191  * bsg_complete - softirq done routine for destroying the bsg requests
192  * @rq: BSG request that holds the job to be destroyed
193  */
194 static void bsg_complete(struct request *rq)
195 {
196         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
197 
198         bsg_job_put(job);
199 }
200 
201 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
202 {
203         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
204 
205         BUG_ON(!req->nr_phys_segments);
206 
207         buf->sg_list = kzalloc(sz, GFP_KERNEL);
208         if (!buf->sg_list)
209                 return -ENOMEM;
210         sg_init_table(buf->sg_list, req->nr_phys_segments);
211         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
212         buf->payload_len = blk_rq_bytes(req);
213         return 0;
214 }
215 
216 /**
217  * bsg_prepare_job - create the bsg_job structure for the bsg request
218  * @dev: device that is being sent the bsg request
219  * @req: BSG request that needs a job structure
220  */
221 static bool bsg_prepare_job(struct device *dev, struct request *req)
222 {
223         struct bsg_job *job = blk_mq_rq_to_pdu(req);
224         int ret;
225 
226         job->timeout = req->timeout;
227 
228         if (req->bio) {
229                 ret = bsg_map_buffer(&job->request_payload, req);
230                 if (ret)
231                         goto failjob_rls_job;
232         }
233         if (job->bidi_rq) {
234                 ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
235                 if (ret)
236                         goto failjob_rls_rqst_payload;
237         }
238         job->dev = dev;
239         /* take a reference for the request */
240         get_device(job->dev);
241         kref_init(&job->kref);
242         return true;
243 
244 failjob_rls_rqst_payload:
245         kfree(job->request_payload.sg_list);
246 failjob_rls_job:
247         job->result = -ENOMEM;
248         return false;
249 }
250 
251 /**
252  * bsg_queue_rq - generic handler for bsg requests
253  * @hctx: hardware queue
254  * @bd: queue data
255  *
256  * On error the create_bsg_job function should return a -Exyz error value
257  * that will be set to ->result.
258  *
259  * Drivers/subsys should pass this to the queue init function.
260  */
261 static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
262                                  const struct blk_mq_queue_data *bd)
263 {
264         struct request_queue *q = hctx->queue;
265         struct device *dev = q->queuedata;
266         struct request *req = bd->rq;
267         struct bsg_set *bset =
268                 container_of(q->tag_set, struct bsg_set, tag_set);
269         blk_status_t sts = BLK_STS_IOERR;
270         int ret;
271 
272         blk_mq_start_request(req);
273 
274         if (!get_device(dev))
275                 return BLK_STS_IOERR;
276 
277         if (!bsg_prepare_job(dev, req))
278                 goto out;
279 
280         ret = bset->job_fn(blk_mq_rq_to_pdu(req));
281         if (!ret)
282                 sts = BLK_STS_OK;
283 
284 out:
285         put_device(dev);
286         return sts;
287 }
288 
289 /* called right after the request is allocated for the request_queue */
290 static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
291                        unsigned int hctx_idx, unsigned int numa_node)
292 {
293         struct bsg_job *job = blk_mq_rq_to_pdu(req);
294 
295         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
296         if (!job->reply)
297                 return -ENOMEM;
298         return 0;
299 }
300 
301 /* called right before the request is given to the request_queue user */
302 static void bsg_initialize_rq(struct request *req)
303 {
304         struct bsg_job *job = blk_mq_rq_to_pdu(req);
305         void *reply = job->reply;
306 
307         memset(job, 0, sizeof(*job));
308         job->reply = reply;
309         job->reply_len = SCSI_SENSE_BUFFERSIZE;
310         job->dd_data = job + 1;
311 }
312 
313 static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
314                        unsigned int hctx_idx)
315 {
316         struct bsg_job *job = blk_mq_rq_to_pdu(req);
317 
318         kfree(job->reply);
319 }
320 
321 void bsg_remove_queue(struct request_queue *q)
322 {
323         if (q) {
324                 struct bsg_set *bset =
325                         container_of(q->tag_set, struct bsg_set, tag_set);
326 
327                 bsg_unregister_queue(q);
328                 blk_cleanup_queue(q);
329                 blk_mq_free_tag_set(&bset->tag_set);
330                 kfree(bset);
331         }
332 }
333 EXPORT_SYMBOL_GPL(bsg_remove_queue);
334 
335 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
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 
345 static 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         .initialize_rq_fn       = bsg_initialize_rq,
350         .complete               = bsg_complete,
351         .timeout                = bsg_timeout,
352 };
353 
354 /**
355  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
356  * @dev: device to attach bsg device to
357  * @name: device to give bsg device
358  * @job_fn: bsg job handler
359  * @timeout: timeout handler function pointer
360  * @dd_job_size: size of LLD data needed for each job
361  */
362 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
363                 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
364 {
365         struct bsg_set *bset;
366         struct blk_mq_tag_set *set;
367         struct request_queue *q;
368         int ret = -ENOMEM;
369 
370         bset = kzalloc(sizeof(*bset), GFP_KERNEL);
371         if (!bset)
372                 return ERR_PTR(-ENOMEM);
373 
374         bset->job_fn = job_fn;
375         bset->timeout_fn = timeout;
376 
377         set = &bset->tag_set;
378         set->ops = &bsg_mq_ops,
379         set->nr_hw_queues = 1;
380         set->queue_depth = 128;
381         set->numa_node = NUMA_NO_NODE;
382         set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
383         set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
384         if (blk_mq_alloc_tag_set(set))
385                 goto out_tag_set;
386 
387         q = blk_mq_init_queue(set);
388         if (IS_ERR(q)) {
389                 ret = PTR_ERR(q);
390                 goto out_queue;
391         }
392 
393         q->queuedata = dev;
394         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
395 
396         ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
397         if (ret) {
398                 printk(KERN_ERR "%s: bsg interface failed to "
399                        "initialize - register queue\n", dev->kobj.name);
400                 goto out_cleanup_queue;
401         }
402 
403         return q;
404 out_cleanup_queue:
405         blk_cleanup_queue(q);
406 out_queue:
407         blk_mq_free_tag_set(set);
408 out_tag_set:
409         kfree(bset);
410         return ERR_PTR(ret);
411 }
412 EXPORT_SYMBOL_GPL(bsg_setup_queue);
413 

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