FreeBSD/Linux Kernel Cross Reference
sys/block/bsg-lib.c

     /*
      *  BSG helper library
      *
      *  Copyright (C) 2008   James Smart, Emulex Corporation
      *  Copyright (C) 2011   Red Hat, Inc.  All rights reserved.
      *  Copyright (C) 2011   Mike Christie
      *
      *  This program is free software; you can redistribute it and/or modify
      *  it under the terms of the GNU General Public License as published by
     *  the Free Software Foundation; either version 2 of the License, or
     *  (at your option) any later version.
     *
     *  This program is distributed in the hope that it will be useful,
     *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     *  GNU General Public License for more details.
     *
     *  You should have received a copy of the GNU General Public License
     *  along with this program; if not, write to the Free Software
     *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     *
     */
    #include <linux/slab.h>
    #include <linux/blkdev.h>
    #include <linux/delay.h>
    #include <linux/scatterlist.h>
    #include <linux/bsg-lib.h>
    #include <linux/export.h>
    #include <scsi/scsi_cmnd.h>
    
    /**
     * bsg_destroy_job - routine to teardown/delete a bsg job
     * @job: bsg_job that is to be torn down
     */
    static void bsg_destroy_job(struct bsg_job *job)
    {
            put_device(job->dev);   /* release reference for the request */
    
            kfree(job->request_payload.sg_list);
            kfree(job->reply_payload.sg_list);
            kfree(job);
    }
    
    /**
     * bsg_job_done - completion routine for bsg requests
     * @job: bsg_job that is complete
     * @result: job reply result
     * @reply_payload_rcv_len: length of payload recvd
     *
     * The LLD should call this when the bsg job has completed.
     */
    void bsg_job_done(struct bsg_job *job, int result,
                      unsigned int reply_payload_rcv_len)
    {
            struct request *req = job->req;
            struct request *rsp = req->next_rq;
            int err;
    
            err = job->req->errors = result;
            if (err < 0)
                    /* we're only returning the result field in the reply */
                    job->req->sense_len = sizeof(u32);
            else
                    job->req->sense_len = job->reply_len;
            /* we assume all request payload was transferred, residual == 0 */
            req->resid_len = 0;
    
            if (rsp) {
                    WARN_ON(reply_payload_rcv_len > rsp->resid_len);
    
                    /* set reply (bidi) residual */
                    rsp->resid_len -= min(reply_payload_rcv_len, rsp->resid_len);
            }
            blk_complete_request(req);
    }
    EXPORT_SYMBOL_GPL(bsg_job_done);
    
    /**
     * bsg_softirq_done - softirq done routine for destroying the bsg requests
     * @rq: BSG request that holds the job to be destroyed
     */
    static void bsg_softirq_done(struct request *rq)
    {
            struct bsg_job *job = rq->special;
    
            blk_end_request_all(rq, rq->errors);
            bsg_destroy_job(job);
    }
    
    static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
    {
            size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
    
            BUG_ON(!req->nr_phys_segments);
    
            buf->sg_list = kzalloc(sz, GFP_KERNEL);
            if (!buf->sg_list)
                    return -ENOMEM;
            sg_init_table(buf->sg_list, req->nr_phys_segments);
           buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
           buf->payload_len = blk_rq_bytes(req);
           return 0;
   }
   
   /**
    * bsg_create_job - create the bsg_job structure for the bsg request
    * @dev: device that is being sent the bsg request
    * @req: BSG request that needs a job structure
    */
   static int bsg_create_job(struct device *dev, struct request *req)
   {
           struct request *rsp = req->next_rq;
           struct request_queue *q = req->q;
           struct bsg_job *job;
           int ret;
   
           BUG_ON(req->special);
   
           job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
           if (!job)
                   return -ENOMEM;
   
           req->special = job;
           job->req = req;
           if (q->bsg_job_size)
                   job->dd_data = (void *)&job[1];
           job->request = req->cmd;
           job->request_len = req->cmd_len;
           job->reply = req->sense;
           job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
                                                    * allocated */
           if (req->bio) {
                   ret = bsg_map_buffer(&job->request_payload, req);
                   if (ret)
                           goto failjob_rls_job;
           }
           if (rsp && rsp->bio) {
                   ret = bsg_map_buffer(&job->reply_payload, rsp);
                   if (ret)
                           goto failjob_rls_rqst_payload;
           }
           job->dev = dev;
           /* take a reference for the request */
           get_device(job->dev);
           return 0;
   
   failjob_rls_rqst_payload:
           kfree(job->request_payload.sg_list);
   failjob_rls_job:
           kfree(job);
           return -ENOMEM;
   }
   
   /**
    * bsg_request_fn - generic handler for bsg requests
    * @q: request queue to manage
    *
    * On error the create_bsg_job function should return a -Exyz error value
    * that will be set to the req->errors.
    *
    * Drivers/subsys should pass this to the queue init function.
    */
   void bsg_request_fn(struct request_queue *q)
   {
           struct device *dev = q->queuedata;
           struct request *req;
           struct bsg_job *job;
           int ret;
   
           if (!get_device(dev))
                   return;
   
           while (1) {
                   req = blk_fetch_request(q);
                   if (!req)
                           break;
                   spin_unlock_irq(q->queue_lock);
   
                   ret = bsg_create_job(dev, req);
                   if (ret) {
                           req->errors = ret;
                           blk_end_request_all(req, ret);
                           spin_lock_irq(q->queue_lock);
                           continue;
                   }
   
                   job = req->special;
                   ret = q->bsg_job_fn(job);
                   spin_lock_irq(q->queue_lock);
                   if (ret)
                           break;
           }
   
           spin_unlock_irq(q->queue_lock);
           put_device(dev);
           spin_lock_irq(q->queue_lock);
   }
   EXPORT_SYMBOL_GPL(bsg_request_fn);
   
   /**
    * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
    * @dev: device to attach bsg device to
    * @q: request queue setup by caller
    * @name: device to give bsg device
    * @job_fn: bsg job handler
    * @dd_job_size: size of LLD data needed for each job
    *
    * The caller should have setup the reuqest queue with bsg_request_fn
    * as the request_fn.
    */
   int bsg_setup_queue(struct device *dev, struct request_queue *q,
                       char *name, bsg_job_fn *job_fn, int dd_job_size)
   {
           int ret;
   
           q->queuedata = dev;
           q->bsg_job_size = dd_job_size;
           q->bsg_job_fn = job_fn;
           queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
           blk_queue_softirq_done(q, bsg_softirq_done);
           blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
   
           ret = bsg_register_queue(q, dev, name, NULL);
           if (ret) {
                   printk(KERN_ERR "%s: bsg interface failed to "
                          "initialize - register queue\n", dev->kobj.name);
                   return ret;
           }
   
           return 0;
   }
   EXPORT_SYMBOL_GPL(bsg_setup_queue);

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