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/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         struct request *rq = blk_mq_rq_from_pdu(job);
 185
 186         job->result = result;
 187         job->reply_payload_rcv_len = reply_payload_rcv_len;
 188         if (likely(!blk_should_fake_timeout(rq->q)))
 189                 blk_mq_complete_request(rq);
 190 }
 191 EXPORT_SYMBOL_GPL(bsg_job_done);
 192
 193 /**
 194  * bsg_complete - softirq done routine for destroying the bsg requests
 195  * @rq: BSG request that holds the job to be destroyed
 196  */
 197 static void bsg_complete(struct request *rq)
 198 {
 199         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 200
 201         bsg_job_put(job);
 202 }
 203
 204 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 205 {
 206         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 207
 208         BUG_ON(!req->nr_phys_segments);
 209
 210         buf->sg_list = kmalloc(sz, GFP_KERNEL);
 211         if (!buf->sg_list)
 212                 return -ENOMEM;
 213         sg_init_table(buf->sg_list, req->nr_phys_segments);
 214         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 215         buf->payload_len = blk_rq_bytes(req);
 216         return 0;
 217 }
 218
 219 /**
 220  * bsg_prepare_job - create the bsg_job structure for the bsg request
 221  * @dev: device that is being sent the bsg request
 222  * @req: BSG request that needs a job structure
 223  */
 224 static bool bsg_prepare_job(struct device *dev, struct request *req)
 225 {
 226         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 227         int ret;
 228
 229         job->timeout = req->timeout;
 230
 231         if (req->bio) {
 232                 ret = bsg_map_buffer(&job->request_payload, req);
 233                 if (ret)
 234                         goto failjob_rls_job;
 235         }
 236         if (job->bidi_rq) {
 237                 ret = bsg_map_buffer(&job->reply_payload, job->bidi_rq);
 238                 if (ret)
 239                         goto failjob_rls_rqst_payload;
 240         }
 241         job->dev = dev;
 242         /* take a reference for the request */
 243         get_device(job->dev);
 244         kref_init(&job->kref);
 245         return true;
 246
 247 failjob_rls_rqst_payload:
 248         kfree(job->request_payload.sg_list);
 249 failjob_rls_job:
 250         job->result = -ENOMEM;
 251         return false;
 252 }
 253
 254 /**
 255  * bsg_queue_rq - generic handler for bsg requests
 256  * @hctx: hardware queue
 257  * @bd: queue data
 258  *
 259  * On error the create_bsg_job function should return a -Exyz error value
 260  * that will be set to ->result.
 261  *
 262  * Drivers/subsys should pass this to the queue init function.
 263  */
 264 static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx,
 265                                  const struct blk_mq_queue_data *bd)
 266 {
 267         struct request_queue *q = hctx->queue;
 268         struct device *dev = q->queuedata;
 269         struct request *req = bd->rq;
 270         struct bsg_set *bset =
 271                 container_of(q->tag_set, struct bsg_set, tag_set);
 272         blk_status_t sts = BLK_STS_IOERR;
 273         int ret;
 274
 275         blk_mq_start_request(req);
 276
 277         if (!get_device(dev))
 278                 return BLK_STS_IOERR;
 279
 280         if (!bsg_prepare_job(dev, req))
 281                 goto out;
 282
 283         ret = bset->job_fn(blk_mq_rq_to_pdu(req));
 284         if (!ret)
 285                 sts = BLK_STS_OK;
 286
 287 out:
 288         put_device(dev);
 289         return sts;
 290 }
 291
 292 /* called right after the request is allocated for the request_queue */
 293 static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req,
 294                        unsigned int hctx_idx, unsigned int numa_node)
 295 {
 296         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 297
 298         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
 299         if (!job->reply)
 300                 return -ENOMEM;
 301         return 0;
 302 }
 303
 304 /* called right before the request is given to the request_queue user */
 305 static void bsg_initialize_rq(struct request *req)
 306 {
 307         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 308         void *reply = job->reply;
 309
 310         memset(job, 0, sizeof(*job));
 311         job->reply = reply;
 312         job->reply_len = SCSI_SENSE_BUFFERSIZE;
 313         job->dd_data = job + 1;
 314 }
 315
 316 static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req,
 317                        unsigned int hctx_idx)
 318 {
 319         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 320
 321         kfree(job->reply);
 322 }
 323
 324 void bsg_remove_queue(struct request_queue *q)
 325 {
 326         if (q) {
 327                 struct bsg_set *bset =
 328                         container_of(q->tag_set, struct bsg_set, tag_set);
 329
 330                 bsg_unregister_queue(q);
 331                 blk_cleanup_queue(q);
 332                 blk_mq_free_tag_set(&bset->tag_set);
 333                 kfree(bset);
 334         }
 335 }
 336 EXPORT_SYMBOL_GPL(bsg_remove_queue);
 337
 338 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved)
 339 {
 340         struct bsg_set *bset =
 341                 container_of(rq->q->tag_set, struct bsg_set, tag_set);
 342
 343         if (!bset->timeout_fn)
 344                 return BLK_EH_DONE;
 345         return bset->timeout_fn(rq);
 346 }
 347
 348 static const struct blk_mq_ops bsg_mq_ops = {
 349         .queue_rq               = bsg_queue_rq,
 350         .init_request           = bsg_init_rq,
 351         .exit_request           = bsg_exit_rq,
 352         .initialize_rq_fn       = bsg_initialize_rq,
 353         .complete               = bsg_complete,
 354         .timeout                = bsg_timeout,
 355 };
 356
 357 /**
 358  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 359  * @dev: device to attach bsg device to
 360  * @name: device to give bsg device
 361  * @job_fn: bsg job handler
 362  * @timeout: timeout handler function pointer
 363  * @dd_job_size: size of LLD data needed for each job
 364  */
 365 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 366                 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size)
 367 {
 368         struct bsg_set *bset;
 369         struct blk_mq_tag_set *set;
 370         struct request_queue *q;
 371         int ret = -ENOMEM;
 372
 373         bset = kzalloc(sizeof(*bset), GFP_KERNEL);
 374         if (!bset)
 375                 return ERR_PTR(-ENOMEM);
 376
 377         bset->job_fn = job_fn;
 378         bset->timeout_fn = timeout;
 379
 380         set = &bset->tag_set;
 381         set->ops = &bsg_mq_ops;
 382         set->nr_hw_queues = 1;
 383         set->queue_depth = 128;
 384         set->numa_node = NUMA_NO_NODE;
 385         set->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 386         set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING;
 387         if (blk_mq_alloc_tag_set(set))
 388                 goto out_tag_set;
 389
 390         q = blk_mq_init_queue(set);
 391         if (IS_ERR(q)) {
 392                 ret = PTR_ERR(q);
 393                 goto out_queue;
 394         }
 395
 396         q->queuedata = dev;
 397         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 398
 399         ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
 400         if (ret) {
 401                 printk(KERN_ERR "%s: bsg interface failed to "
 402                        "initialize - register queue\n", dev->kobj.name);
 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);