linux/block/bsg-lib.c
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   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_destroy_job - routine to teardown/delete a bsg job
  33 * @job: bsg_job that is to be torn down
  34 */
  35static void bsg_destroy_job(struct bsg_job *job)
  36{
  37        put_device(job->dev);   /* release reference for the request */
  38
  39        kfree(job->request_payload.sg_list);
  40        kfree(job->reply_payload.sg_list);
  41        kfree(job);
  42}
  43
  44/**
  45 * bsg_job_done - completion routine for bsg requests
  46 * @job: bsg_job that is complete
  47 * @result: job reply result
  48 * @reply_payload_rcv_len: length of payload recvd
  49 *
  50 * The LLD should call this when the bsg job has completed.
  51 */
  52void bsg_job_done(struct bsg_job *job, int result,
  53                  unsigned int reply_payload_rcv_len)
  54{
  55        struct request *req = job->req;
  56        struct request *rsp = req->next_rq;
  57        int err;
  58
  59        err = job->req->errors = result;
  60        if (err < 0)
  61                /* we're only returning the result field in the reply */
  62                job->req->sense_len = sizeof(u32);
  63        else
  64                job->req->sense_len = job->reply_len;
  65        /* we assume all request payload was transferred, residual == 0 */
  66        req->resid_len = 0;
  67
  68        if (rsp) {
  69                WARN_ON(reply_payload_rcv_len > rsp->resid_len);
  70
  71                /* set reply (bidi) residual */
  72                rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
  73        }
  74        blk_complete_request(req);
  75}
  76EXPORT_SYMBOL_GPL(bsg_job_done);
  77
  78/**
  79 * bsg_softirq_done - softirq done routine for destroying the bsg requests
  80 * @rq: BSG request that holds the job to be destroyed
  81 */
  82static void bsg_softirq_done(struct request *rq)
  83{
  84        struct bsg_job *job = rq->special;
  85
  86        blk_end_request_all(rq, rq->errors);
  87        bsg_destroy_job(job);
  88}
  89
  90static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
  91{
  92        size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
  93
  94        BUG_ON(!req->nr_phys_segments);
  95
  96        buf->sg_list = kzalloc(sz, GFP_KERNEL);
  97        if (!buf->sg_list)
  98                return -ENOMEM;
  99        sg_init_table(buf->sg_list, req->nr_phys_segments);
 100        buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
 101        buf->payload_len = blk_rq_bytes(req);
 102        return 0;
 103}
 104
 105/**
 106 * bsg_create_job - create the bsg_job structure for the bsg request
 107 * @dev: device that is being sent the bsg request
 108 * @req: BSG request that needs a job structure
 109 */
 110static int bsg_create_job(struct device *dev, struct request *req)
 111{
 112        struct request *rsp = req->next_rq;
 113        struct request_queue *q = req->q;
 114        struct bsg_job *job;
 115        int ret;
 116
 117        BUG_ON(req->special);
 118
 119        job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
 120        if (!job)
 121                return -ENOMEM;
 122
 123        req->special = job;
 124        job->req = req;
 125        if (q->bsg_job_size)
 126                job->dd_data = (void *)&job[1];
 127        job->request = req->cmd;
 128        job->request_len = req->cmd_len;
 129        job->reply = req->sense;
 130        job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
 131                                                 * allocated */
 132        if (req->bio) {
 133                ret = bsg_map_buffer(&job->request_payload, req);
 134                if (ret)
 135                        goto failjob_rls_job;
 136        }
 137        if (rsp && rsp->bio) {
 138                ret = bsg_map_buffer(&job->reply_payload, rsp);
 139                if (ret)
 140                        goto failjob_rls_rqst_payload;
 141        }
 142        job->dev = dev;
 143        /* take a reference for the request */
 144        get_device(job->dev);
 145        return 0;
 146
 147failjob_rls_rqst_payload:
 148        kfree(job->request_payload.sg_list);
 149failjob_rls_job:
 150        kfree(job);
 151        return -ENOMEM;
 152}
 153
 154/**
 155 * bsg_request_fn - generic handler for bsg requests
 156 * @q: request queue to manage
 157 *
 158 * On error the create_bsg_job function should return a -Exyz error value
 159 * that will be set to the req->errors.
 160 *
 161 * Drivers/subsys should pass this to the queue init function.
 162 */
 163void bsg_request_fn(struct request_queue *q)
 164{
 165        struct device *dev = q->queuedata;
 166        struct request *req;
 167        struct bsg_job *job;
 168        int ret;
 169
 170        if (!get_device(dev))
 171                return;
 172
 173        while (1) {
 174                req = blk_fetch_request(q);
 175                if (!req)
 176                        break;
 177                spin_unlock_irq(q->queue_lock);
 178
 179                ret = bsg_create_job(dev, req);
 180                if (ret) {
 181                        req->errors = ret;
 182                        blk_end_request_all(req, ret);
 183                        spin_lock_irq(q->queue_lock);
 184                        continue;
 185                }
 186
 187                job = req->special;
 188                ret = q->bsg_job_fn(job);
 189                spin_lock_irq(q->queue_lock);
 190                if (ret)
 191                        break;
 192        }
 193
 194        spin_unlock_irq(q->queue_lock);
 195        put_device(dev);
 196        spin_lock_irq(q->queue_lock);
 197}
 198EXPORT_SYMBOL_GPL(bsg_request_fn);
 199
 200/**
 201 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
 202 * @dev: device to attach bsg device to
 203 * @q: request queue setup by caller
 204 * @name: device to give bsg device
 205 * @job_fn: bsg job handler
 206 * @dd_job_size: size of LLD data needed for each job
 207 *
 208 * The caller should have setup the reuqest queue with bsg_request_fn
 209 * as the request_fn.
 210 */
 211int bsg_setup_queue(struct device *dev, struct request_queue *q,
 212                    char *name, bsg_job_fn *job_fn, int dd_job_size)
 213{
 214        int ret;
 215
 216        q->queuedata = dev;
 217        q->bsg_job_size = dd_job_size;
 218        q->bsg_job_fn = job_fn;
 219        queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
 220        blk_queue_softirq_done(q, bsg_softirq_done);
 221        blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
 222
 223        ret = bsg_register_queue(q, dev, name, NULL);
 224        if (ret) {
 225                printk(KERN_ERR "%s: bsg interface failed to "
 226                       "initialize - register queue\n", dev->kobj.name);
 227                return ret;
 228        }
 229
 230        return 0;
 231}
 232EXPORT_SYMBOL_GPL(bsg_setup_queue);
 233
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