block/bsg-lib.c

   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(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_mq_destroy_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)
 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_mq_destroy_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);