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         int ret;
  35
  36         if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
  37             hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT)
  38                 return -EINVAL;
  39         if (!capable(CAP_SYS_RAWIO))
  40                 return -EPERM;
  41
  42         rq = blk_get_request(q, hdr->dout_xfer_len ?
  43                              REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
  44         if (IS_ERR(rq))
  45                 return PTR_ERR(rq);
  46         rq->timeout = timeout;
  47
  48         job = blk_mq_rq_to_pdu(rq);
  49         job->request_len = hdr->request_len;
  50         job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
  51         if (IS_ERR(job->request)) {
  52                 ret = PTR_ERR(job->request);
  53                 goto out_put_request;
  54         }
  55
  56         if (hdr->dout_xfer_len && hdr->din_xfer_len) {
  57                 job->bidi_rq = blk_get_request(rq->q, REQ_OP_DRV_IN, 0);
  58                 if (IS_ERR(job->bidi_rq)) {
  59                         ret = PTR_ERR(job->bidi_rq);
  60                         goto out_free_job_request;
  61                 }
  62
  63                 ret = blk_rq_map_user(rq->q, job->bidi_rq, NULL,
  64                                 uptr64(hdr->din_xferp), hdr->din_xfer_len,
  65                                 GFP_KERNEL);
  66                 if (ret)
  67                         goto out_free_bidi_rq;
  68
  69                 job->bidi_bio = job->bidi_rq->bio;
  70         } else {
  71                 job->bidi_rq = NULL;
  72                 job->bidi_bio = NULL;
  73         }
  74
  75         ret = 0;
  76         if (hdr->dout_xfer_len) {
  77                 ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->dout_xferp),
  78                                 hdr->dout_xfer_len, GFP_KERNEL);
  79         } else if (hdr->din_xfer_len) {
  80                 ret = blk_rq_map_user(rq->q, rq, NULL, uptr64(hdr->din_xferp),
  81                                 hdr->din_xfer_len, GFP_KERNEL);
  82         }
  83
  84         if (ret)
  85                 goto out_unmap_bidi_rq;
  86
  87         bio = rq->bio;
  88         blk_execute_rq(NULL, rq, !(hdr->flags & BSG_FLAG_Q_AT_TAIL));
  89
  90         /*
  91          * The assignments below don't make much sense, but are kept for
  92          * bug by bug backwards compatibility:
  93          */
  94         hdr->device_status = job->result & 0xff;
  95         hdr->transport_status = host_byte(job->result);
  96         hdr->driver_status = 0;
  97         hdr->info = 0;
  98         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
  99                 hdr->info |= SG_INFO_CHECK;
 100         hdr->response_len = 0;
 101
 102         if (job->result < 0) {
 103                 /* we're only returning the result field in the reply */
 104                 job->reply_len = sizeof(u32);
 105                 ret = job->result;
 106         }
 107
 108         if (job->reply_len && hdr->response) {
 109                 int len = min(hdr->max_response_len, job->reply_len);
 110
 111                 if (copy_to_user(uptr64(hdr->response), job->reply, len))
 112                         ret = -EFAULT;
 113                 else
 114                         hdr->response_len = len;
 115         }
 116
 117         /* we assume all request payload was transferred, residual == 0 */
 118         hdr->dout_resid = 0;
 119
 120         if (job->bidi_rq) {
 121                 unsigned int rsp_len = job->reply_payload.payload_len;
 122
 123                 if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
 124                         hdr->din_resid = 0;
 125                 else
 126                         hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
 127         } else {
 128                 hdr->din_resid = 0;
 129         }
 130
 131         blk_rq_unmap_user(bio);
 132 out_unmap_bidi_rq:
 133         if (job->bidi_rq)
 134                 blk_rq_unmap_user(job->bidi_bio);
 135 out_free_bidi_rq:
 136         if (job->bidi_rq)
 137                 blk_put_request(job->bidi_rq);
 138 out_free_job_request:
 139         kfree(job->request);
 140 out_put_request:
 141         blk_put_request(rq);
 142         return ret;
 143 }
 144
 145 /**
 146  * bsg_teardown_job - routine to teardown a bsg job
 147  * @kref: kref inside bsg_job that is to be torn down
 148  */
 149 static void bsg_teardown_job(struct kref *kref)
 150 {
 151         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
 152         struct request *rq = blk_mq_rq_from_pdu(job);
 153
 154         put_device(job->dev);   /* release reference for the request */
 155
 156         kfree(job->request_payload.sg_list);
 157         kfree(job->reply_payload.sg_list);
 158
 159         blk_mq_end_request(rq, BLK_STS_OK);
 160 }
 161
 162 void bsg_job_put(struct bsg_job *job)
 163 {
 164         kref_put(&job->kref, bsg_teardown_job);
 165 }
 166 EXPORT_SYMBOL_GPL(bsg_job_put);
 167
 168 int bsg_job_get(struct bsg_job *job)
 169 {
 170         return kref_get_unless_zero(&job->kref);
 171 }
 172 EXPORT_SYMBOL_GPL(bsg_job_get);
 173
 174 /**
 175  * bsg_job_done - completion routine for bsg requests
 176  * @job: bsg_job that is complete
 177  * @result: job reply result
 178  * @reply_payload_rcv_len: length of payload recvd
 179  *
 180  * The LLD should call this when the bsg job has completed.
 181  */
 182 void bsg_job_done(struct bsg_job *job, int result,
 183                   unsigned int reply_payload_rcv_len)
 184 {
 185         struct request *rq = blk_mq_rq_from_pdu(job);
 186
 187         job->result = result;
 188         job->reply_payload_rcv_len = reply_payload_rcv_len;
 189         if (likely(!blk_should_fake_timeout(rq->q)))
 190                 blk_mq_complete_request(rq);
 191 }
 192 EXPORT_SYMBOL_GPL(bsg_job_done);
 193
 194 /**
 195  * bsg_complete - softirq done routine for destroying the bsg requests
 196  * @rq: BSG request that holds the job to be destroyed
 197  */
 198 static void bsg_complete(struct request *rq)
 199 {
 200         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 201
 202         bsg_job_put(job);
 203 }
 204
 205 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 206 {
 207         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 208
 209         BUG_ON(!req->nr_phys_segments);
 210
 211         buf->sg_list = kmalloc(sz, GFP_KERNEL);
 212         if (!buf->sg_list)
 213                 return -ENOMEM;
 214         sg_init_table(buf->sg_list, req->nr_phys_segments);
 215         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 216         buf->payload_len = blk_rq_bytes(req);
 217         return 0;
 218 }
 219
 220 /**
 221  * bsg_prepare_job - create the bsg_job structure for the bsg request
 222  * @dev: device that is being sent the bsg request
 223  * @req: BSG request that needs a job structure
 224  */
 225 static bool bsg_prepare_job(struct device *dev, struct request *req)
 226 {
 227         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 228         int ret;
 229
 230         job->timeout = req->timeout;
 231
 232         if (req->bio) {
 233                 ret = bsg_map_buffer(&job->request_payload, req);
 234                 if (ret)
 235                         goto failjob_rls_job;
 236         }
 237         if (job->bidi_rq) {
 238                 ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
 239                 if (ret)
 240                         goto failjob_rls_rqst_payload;
 241         }
 242         job->dev = dev;
 243         /* take a reference for the request */
 244         get_device(job->dev);
 245         kref_init(&job->kref);
 246         return true;
 247
 248 failjob_rls_rqst_payload:
 249         kfree(job->request_payload.sg_list);
 250 failjob_rls_job:
 251         job->result = -ENOMEM;
 252         return false;
 253 }
 254
 255 /**
 256  * bsg_queue_rq - generic handler for bsg requests
 257  * @hctx: hardware queue
 258  * @bd: queue data
 259  *
 260  * On error the create_bsg_job function should return a -Exyz error value
 261  * that will be set to ->result.
 262  *
 263  * Drivers/subsys should pass this to the queue init function.
 264  */
 265 static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
 266                                  const struct blk_mq_queue_data *bd)
 267 {
 268         struct request_queue *q = hctx->queue;
 269         struct device *dev = q->queuedata;
 270         struct request *req = bd->rq;
 271         struct bsg_set *bset =
 272                 container_of(q->tag_set, struct bsg_set, tag_set);
 273         blk_status_t sts = BLK_STS_IOERR;
 274         int ret;
 275
 276         blk_mq_start_request(req);
 277
 278         if (!get_device(dev))
 279                 return BLK_STS_IOERR;
 280
 281         if (!bsg_prepare_job(dev, req))
 282                 goto out;
 283
 284         ret = bset->job_fn(blk_mq_rq_to_pdu(req));
 285         if (!ret)
 286                 sts = BLK_STS_OK;
 287
 288 out:
 289         put_device(dev);
 290         return sts;
 291 }
 292
 293 /* called right after the request is allocated for the request_queue */
 294 static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
 295                        unsigned int hctx_idx, unsigned int numa_node)
 296 {
 297         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 298
 299         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
 300         if (!job->reply)
 301                 return -ENOMEM;
 302         return 0;
 303 }
 304
 305 /* called right before the request is given to the request_queue user */
 306 static void bsg_initialize_rq(struct request *req)
 307 {
 308         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 309         void *reply = job->reply;
 310
 311         memset(job, 0, sizeof(*job));
 312         job->reply = reply;
 313         job->reply_len = SCSI_SENSE_BUFFERSIZE;
 314         job->dd_data = job + 1;
 315 }
 316
 317 static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
 318                        unsigned int hctx_idx)
 319 {
 320         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 321
 322         kfree(job->reply);
 323 }
 324
 325 void bsg_remove_queue(struct request_queue *q)
 326 {
 327         if (q) {
 328                 struct bsg_set *bset =
 329                         container_of(q->tag_set, struct bsg_set, tag_set);
 330
 331                 bsg_unregister_queue(bset->bd);
 332                 blk_cleanup_queue(q);
 333                 blk_mq_free_tag_set(&bset->tag_set);
 334                 kfree(bset);
 335         }
 336 }
 337 EXPORT_SYMBOL_GPL(bsg_remove_queue);
 338
 339 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
 340 {
 341         struct bsg_set *bset =
 342                 container_of(rq->q->tag_set, struct bsg_set, tag_set);
 343
 344         if (!bset->timeout_fn)
 345                 return BLK_EH_DONE;
 346         return bset->timeout_fn(rq);
 347 }
 348
 349 static const struct blk_mq_ops bsg_mq_ops = {
 350         .queue_rq               = bsg_queue_rq,
 351         .init_request           = bsg_init_rq,
 352         .exit_request           = bsg_exit_rq,
 353         .initialize_rq_fn       = bsg_initialize_rq,
 354         .complete               = bsg_complete,
 355         .timeout                = bsg_timeout,
 356 };
 357
 358 /**
 359  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 360  * @dev: device to attach bsg device to
 361  * @name: device to give bsg device
 362  * @job_fn: bsg job handler
 363  * @timeout: timeout handler function pointer
 364  * @dd_job_size: size of LLD data needed for each job
 365  */
 366 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 367                 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
 368 {
 369         struct bsg_set *bset;
 370         struct blk_mq_tag_set *set;
 371         struct request_queue *q;
 372         int ret = -ENOMEM;
 373
 374         bset = kzalloc(sizeof(*bset), GFP_KERNEL);
 375         if (!bset)
 376                 return ERR_PTR(-ENOMEM);
 377
 378         bset->job_fn = job_fn;
 379         bset->timeout_fn = timeout;
 380
 381         set = &bset->tag_set;
 382         set->ops = &bsg_mq_ops;
 383         set->nr_hw_queues = 1;
 384         set->queue_depth = 128;
 385         set->numa_node = NUMA_NO_NODE;
 386         set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 387         set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
 388         if (blk_mq_alloc_tag_set(set))
 389                 goto out_tag_set;
 390
 391         q = blk_mq_init_queue(set);
 392         if (IS_ERR(q)) {
 393                 ret = PTR_ERR(q);
 394                 goto out_queue;
 395         }
 396
 397         q->queuedata = dev;
 398         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 399
 400         bset->bd = bsg_register_queue(q, dev, name, bsg_transport_sg_io_fn);
 401         if (IS_ERR(bset->bd)) {
 402                 ret = PTR_ERR(bset->bd);
 403                 goto out_cleanup_queue;
 404         }
 405
 406         return q;
 407 out_cleanup_queue:
 408         blk_cleanup_queue(q);
 409 out_queue:
 410         blk_mq_free_tag_set(set);
 411 out_tag_set:
 412         kfree(bset);
 413         return ERR_PTR(ret);
 414 }
 415 EXPORT_SYMBOL_GPL(bsg_setup_queue);