block/bsg-lib.c

   1 /*
   2  *  BSG helper library
   3  *
   4  *  Copyright (C) 2008   James Smart, Emulex Corporation
   5  *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
   6  *  Copyright (C) 2011   Mike Christie
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software
  20  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  *
  22  */
  23 #include <linux/slab.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/delay.h>
  26 #include <linux/scatterlist.h>
  27 #include <linux/bsg-lib.h>
  28 #include <linux/export.h>
  29 #include <scsi/scsi_cmnd.h>
  30 #include <scsi/sg.h>
  31
  32 #define uptr64(val) ((void __user *)(uintptr_t)(val))
  33
  34 static int bsg_transport_check_proto(struct sg_io_v4 *hdr)
  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         return 0;
  42 }
  43
  44 static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
  45                 fmode_t mode)
  46 {
  47         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  48
  49         job->request_len = hdr->request_len;
  50         job->request = memdup_user(uptr64(hdr->request), hdr->request_len);
  51
  52         return PTR_ERR_OR_ZERO(job->request);
  53 }
  54
  55 static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
  56 {
  57         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
  58         int ret = 0;
  59
  60         /*
  61          * The assignments below don't make much sense, but are kept for
  62          * bug by bug backwards compatibility:
  63          */
  64         hdr->device_status = job->result & 0xff;
  65         hdr->transport_status = host_byte(job->result);
  66         hdr->driver_status = driver_byte(job->result);
  67         hdr->info = 0;
  68         if (hdr->device_status || hdr->transport_status || hdr->driver_status)
  69                 hdr->info |= SG_INFO_CHECK;
  70         hdr->response_len = 0;
  71
  72         if (job->result < 0) {
  73                 /* we're only returning the result field in the reply */
  74                 job->reply_len = sizeof(u32);
  75                 ret = job->result;
  76         }
  77
  78         if (job->reply_len && hdr->response) {
  79                 int len = min(hdr->max_response_len, job->reply_len);
  80
  81                 if (copy_to_user(uptr64(hdr->response), job->reply, len))
  82                         ret = -EFAULT;
  83                 else
  84                         hdr->response_len = len;
  85         }
  86
  87         /* we assume all request payload was transferred, residual == 0 */
  88         hdr->dout_resid = 0;
  89
  90         if (rq->next_rq) {
  91                 unsigned int rsp_len = job->reply_payload.payload_len;
  92
  93                 if (WARN_ON(job->reply_payload_rcv_len > rsp_len))
  94                         hdr->din_resid = 0;
  95                 else
  96                         hdr->din_resid = rsp_len - job->reply_payload_rcv_len;
  97         } else {
  98                 hdr->din_resid = 0;
  99         }
 100
 101         return ret;
 102 }
 103
 104 static void bsg_transport_free_rq(struct request *rq)
 105 {
 106         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 107
 108         kfree(job->request);
 109 }
 110
 111 static const struct bsg_ops bsg_transport_ops = {
 112         .check_proto            = bsg_transport_check_proto,
 113         .fill_hdr               = bsg_transport_fill_hdr,
 114         .complete_rq            = bsg_transport_complete_rq,
 115         .free_rq                = bsg_transport_free_rq,
 116 };
 117
 118 /**
 119  * bsg_teardown_job - routine to teardown a bsg job
 120  * @kref: kref inside bsg_job that is to be torn down
 121  */
 122 static void bsg_teardown_job(struct kref *kref)
 123 {
 124         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
 125         struct request *rq = blk_mq_rq_from_pdu(job);
 126
 127         put_device(job->dev);   /* release reference for the request */
 128
 129         kfree(job->request_payload.sg_list);
 130         kfree(job->reply_payload.sg_list);
 131
 132         blk_end_request_all(rq, BLK_STS_OK);
 133 }
 134
 135 void bsg_job_put(struct bsg_job *job)
 136 {
 137         kref_put(&job->kref, bsg_teardown_job);
 138 }
 139 EXPORT_SYMBOL_GPL(bsg_job_put);
 140
 141 int bsg_job_get(struct bsg_job *job)
 142 {
 143         return kref_get_unless_zero(&job->kref);
 144 }
 145 EXPORT_SYMBOL_GPL(bsg_job_get);
 146
 147 /**
 148  * bsg_job_done - completion routine for bsg requests
 149  * @job: bsg_job that is complete
 150  * @result: job reply result
 151  * @reply_payload_rcv_len: length of payload recvd
 152  *
 153  * The LLD should call this when the bsg job has completed.
 154  */
 155 void bsg_job_done(struct bsg_job *job, int result,
 156                   unsigned int reply_payload_rcv_len)
 157 {
 158         job->result = result;
 159         job->reply_payload_rcv_len = reply_payload_rcv_len;
 160         blk_complete_request(blk_mq_rq_from_pdu(job));
 161 }
 162 EXPORT_SYMBOL_GPL(bsg_job_done);
 163
 164 /**
 165  * bsg_softirq_done - softirq done routine for destroying the bsg requests
 166  * @rq: BSG request that holds the job to be destroyed
 167  */
 168 static void bsg_softirq_done(struct request *rq)
 169 {
 170         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 171
 172         bsg_job_put(job);
 173 }
 174
 175 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 176 {
 177         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 178
 179         BUG_ON(!req->nr_phys_segments);
 180
 181         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 182         if (!buf->sg_list)
 183                 return -ENOMEM;
 184         sg_init_table(buf->sg_list, req->nr_phys_segments);
 185         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 186         buf->payload_len = blk_rq_bytes(req);
 187         return 0;
 188 }
 189
 190 /**
 191  * bsg_prepare_job - create the bsg_job structure for the bsg request
 192  * @dev: device that is being sent the bsg request
 193  * @req: BSG request that needs a job structure
 194  */
 195 static bool bsg_prepare_job(struct device *dev, struct request *req)
 196 {
 197         struct request *rsp = req->next_rq;
 198         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 199         int ret;
 200
 201         job->timeout = req->timeout;
 202
 203         if (req->bio) {
 204                 ret = bsg_map_buffer(&job->request_payload, req);
 205                 if (ret)
 206                         goto failjob_rls_job;
 207         }
 208         if (rsp && rsp->bio) {
 209                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 210                 if (ret)
 211                         goto failjob_rls_rqst_payload;
 212         }
 213         job->dev = dev;
 214         /* take a reference for the request */
 215         get_device(job->dev);
 216         kref_init(&job->kref);
 217         return true;
 218
 219 failjob_rls_rqst_payload:
 220         kfree(job->request_payload.sg_list);
 221 failjob_rls_job:
 222         job->result = -ENOMEM;
 223         return false;
 224 }
 225
 226 /**
 227  * bsg_request_fn - generic handler for bsg requests
 228  * @q: request queue to manage
 229  *
 230  * On error the create_bsg_job function should return a -Exyz error value
 231  * that will be set to ->result.
 232  *
 233  * Drivers/subsys should pass this to the queue init function.
 234  */
 235 static void bsg_request_fn(struct request_queue *q)
 236         __releases(q->queue_lock)
 237         __acquires(q->queue_lock)
 238 {
 239         struct device *dev = q->queuedata;
 240         struct request *req;
 241         int ret;
 242
 243         if (!get_device(dev))
 244                 return;
 245
 246         while (1) {
 247                 req = blk_fetch_request(q);
 248                 if (!req)
 249                         break;
 250                 spin_unlock_irq(q->queue_lock);
 251
 252                 if (!bsg_prepare_job(dev, req)) {
 253                         blk_end_request_all(req, BLK_STS_OK);
 254                         spin_lock_irq(q->queue_lock);
 255                         continue;
 256                 }
 257
 258                 ret = q->bsg_job_fn(blk_mq_rq_to_pdu(req));
 259                 spin_lock_irq(q->queue_lock);
 260                 if (ret)
 261                         break;
 262         }
 263
 264         spin_unlock_irq(q->queue_lock);
 265         put_device(dev);
 266         spin_lock_irq(q->queue_lock);
 267 }
 268
 269 /* called right after the request is allocated for the request_queue */
 270 static int bsg_init_rq(struct request_queue *q, struct request *req, gfp_t gfp)
 271 {
 272         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 273
 274         job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, gfp);
 275         if (!job->reply)
 276                 return -ENOMEM;
 277         return 0;
 278 }
 279
 280 /* called right before the request is given to the request_queue user */
 281 static void bsg_initialize_rq(struct request *req)
 282 {
 283         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 284         void *reply = job->reply;
 285
 286         memset(job, 0, sizeof(*job));
 287         job->reply = reply;
 288         job->reply_len = SCSI_SENSE_BUFFERSIZE;
 289         job->dd_data = job + 1;
 290 }
 291
 292 static void bsg_exit_rq(struct request_queue *q, struct request *req)
 293 {
 294         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 295
 296         kfree(job->reply);
 297 }
 298
 299 /**
 300  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 301  * @dev: device to attach bsg device to
 302  * @name: device to give bsg device
 303  * @job_fn: bsg job handler
 304  * @dd_job_size: size of LLD data needed for each job
 305  */
 306 struct request_queue *bsg_setup_queue(struct device *dev, const char *name,
 307                 bsg_job_fn *job_fn, int dd_job_size)
 308 {
 309         struct request_queue *q;
 310         int ret;
 311
 312         q = blk_alloc_queue(GFP_KERNEL);
 313         if (!q)
 314                 return ERR_PTR(-ENOMEM);
 315         q->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 316         q->init_rq_fn = bsg_init_rq;
 317         q->exit_rq_fn = bsg_exit_rq;
 318         q->initialize_rq_fn = bsg_initialize_rq;
 319         q->request_fn = bsg_request_fn;
 320
 321         ret = blk_init_allocated_queue(q);
 322         if (ret)
 323                 goto out_cleanup_queue;
 324
 325         q->queuedata = dev;
 326         q->bsg_job_fn = job_fn;
 327         blk_queue_flag_set(QUEUE_FLAG_BIDI, q);
 328         blk_queue_softirq_done(q, bsg_softirq_done);
 329         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 330
 331         ret = bsg_register_queue(q, dev, name, &bsg_transport_ops);
 332         if (ret) {
 333                 printk(KERN_ERR "%s: bsg interface failed to "
 334                        "initialize - register queue\n", dev->kobj.name);
 335                 goto out_cleanup_queue;
 336         }
 337
 338         return q;
 339 out_cleanup_queue:
 340         blk_cleanup_queue(q);
 341         return ERR_PTR(ret);
 342 }
 343 EXPORT_SYMBOL_GPL(bsg_setup_queue);