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 */ 35 static 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 */ 52 void 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 } 76 EXPORT_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 */ 82 static 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 90 static 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 */ 110 static 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; 146 147 failjob_rls_rqst_payload: 148 kfree(job->request_payload.sg_list); 149 failjob_rls_job: 150 kfree(job); 151 return -ENOMEM; 152 } 153 154 /* 155 * bsg_goose_queue - restart queue in case it was stopped 156 * @q: request q to be restarted 157 */ 158 void bsg_goose_queue(struct request_queue *q) 159 { 160 if (!q) 161 return; 162 163 blk_run_queue_async(q); 164 } 165 EXPORT_SYMBOL_GPL(bsg_goose_queue); 166 167 /** 168 * bsg_request_fn - generic handler for bsg requests 169 * @q: request queue to manage 170 * 171 * On error the create_bsg_job function should return a -Exyz error value 172 * that will be set to the req->errors. 173 * 174 * Drivers/subsys should pass this to the queue init function. 175 */ 176 void bsg_request_fn(struct request_queue *q) 177 { 178 struct device *dev = q->queuedata; 179 struct request *req; 180 struct bsg_job *job; 181 int ret; 182 183 if (!get_device(dev)) 184 return; 185 186 while (1) { 187 req = blk_fetch_request(q); 188 if (!req) 189 break; 190 spin_unlock_irq(q->queue_lock); 191 192 ret = bsg_create_job(dev, req); 193 if (ret) { 194 req->errors = ret; 195 blk_end_request_all(req, ret); 196 spin_lock_irq(q->queue_lock); 197 continue; 198 } 199 200 job = req->special; 201 ret = q->bsg_job_fn(job); 202 spin_lock_irq(q->queue_lock); 203 if (ret) 204 break; 205 } 206 207 spin_unlock_irq(q->queue_lock); 208 put_device(dev); 209 spin_lock_irq(q->queue_lock); 210 } 211 EXPORT_SYMBOL_GPL(bsg_request_fn); 212 213 /** 214 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests 215 * @dev: device to attach bsg device to 216 * @q: request queue setup by caller 217 * @name: device to give bsg device 218 * @job_fn: bsg job handler 219 * @dd_job_size: size of LLD data needed for each job 220 * 221 * The caller should have setup the reuqest queue with bsg_request_fn 222 * as the request_fn. 223 */ 224 int bsg_setup_queue(struct device *dev, struct request_queue *q, 225 char *name, bsg_job_fn *job_fn, int dd_job_size) 226 { 227 int ret; 228 229 q->queuedata = dev; 230 q->bsg_job_size = dd_job_size; 231 q->bsg_job_fn = job_fn; 232 queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q); 233 blk_queue_softirq_done(q, bsg_softirq_done); 234 blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT); 235 236 ret = bsg_register_queue(q, dev, name, NULL); 237 if (ret) { 238 printk(KERN_ERR "%s: bsg interface failed to " 239 "initialize - register queue\n", dev->kobj.name); 240 return ret; 241 } 242 243 return 0; 244 } 245 EXPORT_SYMBOL_GPL(bsg_setup_queue); 246 247 /** 248 * bsg_remove_queue - Deletes the bsg dev from the q 249 * @q: the request_queue that is to be torn down. 250 * 251 * Notes: 252 * Before unregistering the queue empty any requests that are blocked 253 */ 254 void bsg_remove_queue(struct request_queue *q) 255 { 256 struct request *req; /* block request */ 257 int counts; /* totals for request_list count and starved */ 258 259 if (!q) 260 return; 261 262 /* Stop taking in new requests */ 263 spin_lock_irq(q->queue_lock); 264 blk_stop_queue(q); 265 266 /* drain all requests in the queue */ 267 while (1) { 268 /* need the lock to fetch a request 269 * this may fetch the same reqeust as the previous pass 270 */ 271 req = blk_fetch_request(q); 272 /* save requests in use and starved */ 273 counts = q->rq.count[0] + q->rq.count[1] + 274 q->rq.starved[0] + q->rq.starved[1]; 275 spin_unlock_irq(q->queue_lock); 276 /* any requests still outstanding? */ 277 if (counts == 0) 278 break; 279 280 /* This may be the same req as the previous iteration, 281 * always send the blk_end_request_all after a prefetch. 282 * It is not okay to not end the request because the 283 * prefetch started the request. 284 */ 285 if (req) { 286 /* return -ENXIO to indicate that this queue is 287 * going away 288 */ 289 req->errors = -ENXIO; 290 blk_end_request_all(req, -ENXIO); 291 } 292 293 msleep(200); /* allow bsg to possibly finish */ 294 spin_lock_irq(q->queue_lock); 295 } 296 bsg_unregister_queue(q); 297 } 298 EXPORT_SYMBOL_GPL(bsg_remove_queue); 299