cregit-Linux how code gets into the kernel

Release 4.9 block/bsg-lib.c

Directory: block
/*
 *  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); }

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/** * 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); }

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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); }

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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; }

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/** * 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; }

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/** * 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); }

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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; }

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EXPORT_SYMBOL_GPL(bsg_setup_queue);

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Directory: block