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
  31 /**
  32  * bsg_teardown_job - routine to teardown a bsg job
  33  * @job: bsg_job that is to be torn down
  34  */
  35 static void bsg_teardown_job(struct kref *kref)
  36 {
  37         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
  38         struct request *rq = job->req;
  39
  40         put_device(job->dev);   /* release reference for the request */
  41
  42         kfree(job->request_payload.sg_list);
  43         kfree(job->reply_payload.sg_list);
  44
  45         blk_end_request_all(rq, BLK_STS_OK);
  46 }
  47
  48 void bsg_job_put(struct bsg_job *job)
  49 {
  50         kref_put(&job->kref, bsg_teardown_job);
  51 }
  52 EXPORT_SYMBOL_GPL(bsg_job_put);
  53
  54 int bsg_job_get(struct bsg_job *job)
  55 {
  56         return kref_get_unless_zero(&job->kref);
  57 }
  58 EXPORT_SYMBOL_GPL(bsg_job_get);
  59
  60 /**
  61  * bsg_job_done - completion routine for bsg requests
  62  * @job: bsg_job that is complete
  63  * @result: job reply result
  64  * @reply_payload_rcv_len: length of payload recvd
  65  *
  66  * The LLD should call this when the bsg job has completed.
  67  */
  68 void bsg_job_done(struct bsg_job *job, int result,
  69                   unsigned int reply_payload_rcv_len)
  70 {
  71         struct request *req = job->req;
  72         struct request *rsp = req->next_rq;
  73         struct scsi_request *rq = scsi_req(req);
  74         int err;
  75
  76         err = scsi_req(job->req)->result = result;
  77         if (err < 0)
  78                 /* we're only returning the result field in the reply */
  79                 rq->sense_len = sizeof(u32);
  80         else
  81                 rq->sense_len = job->reply_len;
  82         /* we assume all request payload was transferred, residual == 0 */
  83         rq->resid_len = 0;
  84
  85         if (rsp) {
  86                 WARN_ON(reply_payload_rcv_len > scsi_req(rsp)->resid_len);
  87
  88                 /* set reply (bidi) residual */
  89                 scsi_req(rsp)->resid_len -=
  90                         min(reply_payload_rcv_len, scsi_req(rsp)->resid_len);
  91         }
  92         blk_complete_request(req);
  93 }
  94 EXPORT_SYMBOL_GPL(bsg_job_done);
  95
  96 /**
  97  * bsg_softirq_done - softirq done routine for destroying the bsg requests
  98  * @rq: BSG request that holds the job to be destroyed
  99  */
 100 static void bsg_softirq_done(struct request *rq)
 101 {
 102         struct bsg_job *job = blk_mq_rq_to_pdu(rq);
 103
 104         bsg_job_put(job);
 105 }
 106
 107 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
 108 {
 109         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
 110
 111         BUG_ON(!req->nr_phys_segments);
 112
 113         buf->sg_list = kzalloc(sz, GFP_KERNEL);
 114         if (!buf->sg_list)
 115                 return -ENOMEM;
 116         sg_init_table(buf->sg_list, req->nr_phys_segments);
 117         scsi_req(req)->resid_len = blk_rq_bytes(req);
 118         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 119         buf->payload_len = blk_rq_bytes(req);
 120         return 0;
 121 }
 122
 123 /**
 124  * bsg_prepare_job - create the bsg_job structure for the bsg request
 125  * @dev: device that is being sent the bsg request
 126  * @req: BSG request that needs a job structure
 127  */
 128 static int bsg_prepare_job(struct device *dev, struct request *req)
 129 {
 130         struct request *rsp = req->next_rq;
 131         struct scsi_request *rq = scsi_req(req);
 132         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 133         int ret;
 134
 135         job->request = rq->cmd;
 136         job->request_len = rq->cmd_len;
 137
 138         if (req->bio) {
 139                 ret = bsg_map_buffer(&job->request_payload, req);
 140                 if (ret)
 141                         goto failjob_rls_job;
 142         }
 143         if (rsp && rsp->bio) {
 144                 ret = bsg_map_buffer(&job->reply_payload, rsp);
 145                 if (ret)
 146                         goto failjob_rls_rqst_payload;
 147         }
 148         job->dev = dev;
 149         /* take a reference for the request */
 150         get_device(job->dev);
 151         kref_init(&job->kref);
 152         return 0;
 153
 154 failjob_rls_rqst_payload:
 155         kfree(job->request_payload.sg_list);
 156 failjob_rls_job:
 157         kfree(job);
 158         return -ENOMEM;
 159 }
 160
 161 /**
 162  * bsg_request_fn - generic handler for bsg requests
 163  * @q: request queue to manage
 164  *
 165  * On error the create_bsg_job function should return a -Exyz error value
 166  * that will be set to ->result.
 167  *
 168  * Drivers/subsys should pass this to the queue init function.
 169  */
 170 static void bsg_request_fn(struct request_queue *q)
 171         __releases(q->queue_lock)
 172         __acquires(q->queue_lock)
 173 {
 174         struct device *dev = q->queuedata;
 175         struct request *req;
 176         int ret;
 177
 178         if (!get_device(dev))
 179                 return;
 180
 181         while (1) {
 182                 req = blk_fetch_request(q);
 183                 if (!req)
 184                         break;
 185                 spin_unlock_irq(q->queue_lock);
 186
 187                 ret = bsg_prepare_job(dev, req);
 188                 if (ret) {
 189                         scsi_req(req)->result = ret;
 190                         blk_end_request_all(req, BLK_STS_OK);
 191                         spin_lock_irq(q->queue_lock);
 192                         continue;
 193                 }
 194
 195                 ret = q->bsg_job_fn(blk_mq_rq_to_pdu(req));
 196                 spin_lock_irq(q->queue_lock);
 197                 if (ret)
 198                         break;
 199         }
 200
 201         spin_unlock_irq(q->queue_lock);
 202         put_device(dev);
 203         spin_lock_irq(q->queue_lock);
 204 }
 205
 206 static int bsg_init_rq(struct request_queue *q, struct request *req, gfp_t gfp)
 207 {
 208         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 209         struct scsi_request *sreq = &job->sreq;
 210
 211         memset(job, 0, sizeof(*job));
 212
 213         scsi_req_init(sreq);
 214         sreq->sense_len = SCSI_SENSE_BUFFERSIZE;
 215         sreq->sense = kzalloc(sreq->sense_len, gfp);
 216         if (!sreq->sense)
 217                 return -ENOMEM;
 218
 219         job->req = req;
 220         job->reply = sreq->sense;
 221         job->reply_len = sreq->sense_len;
 222         job->dd_data = job + 1;
 223
 224         return 0;
 225 }
 226
 227 static void bsg_exit_rq(struct request_queue *q, struct request *req)
 228 {
 229         struct bsg_job *job = blk_mq_rq_to_pdu(req);
 230         struct scsi_request *sreq = &job->sreq;
 231
 232         kfree(sreq->sense);
 233 }
 234
 235 /**
 236  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 237  * @dev: device to attach bsg device to
 238  * @name: device to give bsg device
 239  * @job_fn: bsg job handler
 240  * @dd_job_size: size of LLD data needed for each job
 241  */
 242 struct request_queue *bsg_setup_queue(struct device *dev, char *name,
 243                 bsg_job_fn *job_fn, int dd_job_size)
 244 {
 245         struct request_queue *q;
 246         int ret;
 247
 248         q = blk_alloc_queue(GFP_KERNEL);
 249         if (!q)
 250                 return ERR_PTR(-ENOMEM);
 251         q->cmd_size = sizeof(struct bsg_job) + dd_job_size;
 252         q->init_rq_fn = bsg_init_rq;
 253         q->exit_rq_fn = bsg_exit_rq;
 254         q->request_fn = bsg_request_fn;
 255
 256         ret = blk_init_allocated_queue(q);
 257         if (ret)
 258                 goto out_cleanup_queue;
 259
 260         q->queuedata = dev;
 261         q->bsg_job_fn = job_fn;
 262         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 263         queue_flag_set_unlocked(QUEUE_FLAG_SCSI_PASSTHROUGH, q);
 264         blk_queue_softirq_done(q, bsg_softirq_done);
 265         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 266
 267         ret = bsg_register_queue(q, dev, name, NULL);
 268         if (ret) {
 269                 printk(KERN_ERR "%s: bsg interface failed to "
 270                        "initialize - register queue\n", dev->kobj.name);
 271                 goto out_cleanup_queue;
 272         }
 273
 274         return q;
 275 out_cleanup_queue:
 276         blk_cleanup_queue(q);
 277         return ERR_PTR(ret);
 278 }
 279 EXPORT_SYMBOL_GPL(bsg_setup_queue);