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/blk-mq.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 #include <scsi/sg.h> 31 32 #define uptr64(val) ((void __user *)(uintptr_t)(val)) 33 34 struct bsg_set { 35 struct blk_mq_tag_set tag_set; 36 bsg_job_fn *job_fn; 37 bsg_timeout_fn *timeout_fn; 38 }; 39 40 static int bsg_transport_check_proto(struct sg_io_v4 *hdr) 41 { 42 if (hdr->protocol != BSG_PROTOCOL_SCSI || 43 hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_TRANSPORT) 44 return -EINVAL; 45 if (!capable(CAP_SYS_RAWIO)) 46 return -EPERM; 47 return 0; 48 } 49 50 static int bsg_transport_fill_hdr(struct request *rq, struct sg_io_v4 *hdr, 51 fmode_t mode) 52 { 53 struct bsg_job *job = blk_mq_rq_to_pdu(rq); 54 55 job->request_len = hdr->request_len; 56 job->request = memdup_user(uptr64(hdr->request), hdr->request_len); 57 58 return PTR_ERR_OR_ZERO(job->request); 59 } 60 61 static int bsg_transport_complete_rq(struct request *rq, struct sg_io_v4 *hdr) 62 { 63 struct bsg_job *job = blk_mq_rq_to_pdu(rq); 64 int ret = 0; 65 66 /* 67 * The assignments below don't make much sense, but are kept for 68 * bug by bug backwards compatibility: 69 */ 70 hdr->device_status = job->result & 0xff; 71 hdr->transport_status = host_byte(job->result); 72 hdr->driver_status = driver_byte(job->result); 73 hdr->info = 0; 74 if (hdr->device_status || hdr->transport_status || hdr->driver_status) 75 hdr->info |= SG_INFO_CHECK; 76 hdr->response_len = 0; 77 78 if (job->result < 0) { 79 /* we're only returning the result field in the reply */ 80 job->reply_len = sizeof(u32); 81 ret = job->result; 82 } 83 84 if (job->reply_len && hdr->response) { 85 int len = min(hdr->max_response_len, job->reply_len); 86 87 if (copy_to_user(uptr64(hdr->response), job->reply, len)) 88 ret = -EFAULT; 89 else 90 hdr->response_len = len; 91 } 92 93 /* we assume all request payload was transferred, residual == 0 */ 94 hdr->dout_resid = 0; 95 96 if (rq->next_rq) { 97 unsigned int rsp_len = job->reply_payload.payload_len; 98 99 if (WARN_ON(job->reply_payload_rcv_len > rsp_len)) 100 hdr->din_resid = 0; 101 else 102 hdr->din_resid = rsp_len - job->reply_payload_rcv_len; 103 } else { 104 hdr->din_resid = 0; 105 } 106 107 return ret; 108 } 109 110 static void bsg_transport_free_rq(struct request *rq) 111 { 112 struct bsg_job *job = blk_mq_rq_to_pdu(rq); 113 114 kfree(job->request); 115 } 116 117 static const struct bsg_ops bsg_transport_ops = { 118 .check_proto = bsg_transport_check_proto, 119 .fill_hdr = bsg_transport_fill_hdr, 120 .complete_rq = bsg_transport_complete_rq, 121 .free_rq = bsg_transport_free_rq, 122 }; 123 124 /** 125 * bsg_teardown_job - routine to teardown a bsg job 126 * @kref: kref inside bsg_job that is to be torn down 127 */ 128 static void bsg_teardown_job(struct kref *kref) 129 { 130 struct bsg_job *job = container_of(kref, struct bsg_job, kref); 131 struct request *rq = blk_mq_rq_from_pdu(job); 132 133 put_device(job->dev); /* release reference for the request */ 134 135 kfree(job->request_payload.sg_list); 136 kfree(job->reply_payload.sg_list); 137 138 blk_mq_end_request(rq, BLK_STS_OK); 139 } 140 141 void bsg_job_put(struct bsg_job *job) 142 { 143 kref_put(&job->kref, bsg_teardown_job); 144 } 145 EXPORT_SYMBOL_GPL(bsg_job_put); 146 147 int bsg_job_get(struct bsg_job *job) 148 { 149 return kref_get_unless_zero(&job->kref); 150 } 151 EXPORT_SYMBOL_GPL(bsg_job_get); 152 153 /** 154 * bsg_job_done - completion routine for bsg requests 155 * @job: bsg_job that is complete 156 * @result: job reply result 157 * @reply_payload_rcv_len: length of payload recvd 158 * 159 * The LLD should call this when the bsg job has completed. 160 */ 161 void bsg_job_done(struct bsg_job *job, int result, 162 unsigned int reply_payload_rcv_len) 163 { 164 job->result = result; 165 job->reply_payload_rcv_len = reply_payload_rcv_len; 166 blk_mq_complete_request(blk_mq_rq_from_pdu(job)); 167 } 168 EXPORT_SYMBOL_GPL(bsg_job_done); 169 170 /** 171 * bsg_complete - softirq done routine for destroying the bsg requests 172 * @rq: BSG request that holds the job to be destroyed 173 */ 174 static void bsg_complete(struct request *rq) 175 { 176 struct bsg_job *job = blk_mq_rq_to_pdu(rq); 177 178 bsg_job_put(job); 179 } 180 181 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req) 182 { 183 size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments); 184 185 BUG_ON(!req->nr_phys_segments); 186 187 buf->sg_list = kzalloc(sz, GFP_KERNEL); 188 if (!buf->sg_list) 189 return -ENOMEM; 190 sg_init_table(buf->sg_list, req->nr_phys_segments); 191 buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list); 192 buf->payload_len = blk_rq_bytes(req); 193 return 0; 194 } 195 196 /** 197 * bsg_prepare_job - create the bsg_job structure for the bsg request 198 * @dev: device that is being sent the bsg request 199 * @req: BSG request that needs a job structure 200 */ 201 static bool bsg_prepare_job(struct device *dev, struct request *req) 202 { 203 struct request *rsp = req->next_rq; 204 struct bsg_job *job = blk_mq_rq_to_pdu(req); 205 int ret; 206 207 job->timeout = req->timeout; 208 209 if (req->bio) { 210 ret = bsg_map_buffer(&job->request_payload, req); 211 if (ret) 212 goto failjob_rls_job; 213 } 214 if (rsp && rsp->bio) { 215 ret = bsg_map_buffer(&job->reply_payload, rsp); 216 if (ret) 217 goto failjob_rls_rqst_payload; 218 } 219 job->dev = dev; 220 /* take a reference for the request */ 221 get_device(job->dev); 222 kref_init(&job->kref); 223 return true; 224 225 failjob_rls_rqst_payload: 226 kfree(job->request_payload.sg_list); 227 failjob_rls_job: 228 job->result = -ENOMEM; 229 return false; 230 } 231 232 /** 233 * bsg_queue_rq - generic handler for bsg requests 234 * @hctx: hardware queue 235 * @bd: queue data 236 * 237 * On error the create_bsg_job function should return a -Exyz error value 238 * that will be set to ->result. 239 * 240 * Drivers/subsys should pass this to the queue init function. 241 */ 242 static blk_status_t bsg_queue_rq(struct blk_mq_hw_ctx *hctx, 243 const struct blk_mq_queue_data *bd) 244 { 245 struct request_queue *q = hctx->queue; 246 struct device *dev = q->queuedata; 247 struct request *req = bd->rq; 248 struct bsg_set *bset = 249 container_of(q->tag_set, struct bsg_set, tag_set); 250 int ret; 251 252 blk_mq_start_request(req); 253 254 if (!get_device(dev)) 255 return BLK_STS_IOERR; 256 257 if (!bsg_prepare_job(dev, req)) 258 return BLK_STS_IOERR; 259 260 ret = bset->job_fn(blk_mq_rq_to_pdu(req)); 261 if (ret) 262 return BLK_STS_IOERR; 263 264 put_device(dev); 265 return BLK_STS_OK; 266 } 267 268 /* called right after the request is allocated for the request_queue */ 269 static int bsg_init_rq(struct blk_mq_tag_set *set, struct request *req, 270 unsigned int hctx_idx, unsigned int numa_node) 271 { 272 struct bsg_job *job = blk_mq_rq_to_pdu(req); 273 274 job->reply = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL); 275 if (!job->reply) 276 return -ENOMEM; 277 return 0; 278 } 279 280 /* called right before the request is given to the request_queue user */ 281 static void bsg_initialize_rq(struct request *req) 282 { 283 struct bsg_job *job = blk_mq_rq_to_pdu(req); 284 void *reply = job->reply; 285 286 memset(job, 0, sizeof(*job)); 287 job->reply = reply; 288 job->reply_len = SCSI_SENSE_BUFFERSIZE; 289 job->dd_data = job + 1; 290 } 291 292 static void bsg_exit_rq(struct blk_mq_tag_set *set, struct request *req, 293 unsigned int hctx_idx) 294 { 295 struct bsg_job *job = blk_mq_rq_to_pdu(req); 296 297 kfree(job->reply); 298 } 299 300 void bsg_remove_queue(struct request_queue *q) 301 { 302 if (q) { 303 struct bsg_set *bset = 304 container_of(q->tag_set, struct bsg_set, tag_set); 305 306 bsg_unregister_queue(q); 307 blk_cleanup_queue(q); 308 blk_mq_free_tag_set(&bset->tag_set); 309 kfree(bset); 310 } 311 } 312 EXPORT_SYMBOL_GPL(bsg_remove_queue); 313 314 static enum blk_eh_timer_return bsg_timeout(struct request *rq, bool reserved) 315 { 316 struct bsg_set *bset = 317 container_of(rq->q->tag_set, struct bsg_set, tag_set); 318 319 if (!bset->timeout_fn) 320 return BLK_EH_DONE; 321 return bset->timeout_fn(rq); 322 } 323 324 static const struct blk_mq_ops bsg_mq_ops = { 325 .queue_rq = bsg_queue_rq, 326 .init_request = bsg_init_rq, 327 .exit_request = bsg_exit_rq, 328 .initialize_rq_fn = bsg_initialize_rq, 329 .complete = bsg_complete, 330 .timeout = bsg_timeout, 331 }; 332 333 /** 334 * bsg_setup_queue - Create and add the bsg hooks so we can receive requests 335 * @dev: device to attach bsg device to 336 * @name: device to give bsg device 337 * @job_fn: bsg job handler 338 * @dd_job_size: size of LLD data needed for each job 339 */ 340 struct request_queue *bsg_setup_queue(struct device *dev, const char *name, 341 bsg_job_fn *job_fn, bsg_timeout_fn *timeout, int dd_job_size) 342 { 343 struct bsg_set *bset; 344 struct blk_mq_tag_set *set; 345 struct request_queue *q; 346 int ret = -ENOMEM; 347 348 bset = kzalloc(sizeof(*bset), GFP_KERNEL); 349 if (!bset) 350 return ERR_PTR(-ENOMEM); 351 352 bset->job_fn = job_fn; 353 bset->timeout_fn = timeout; 354 355 set = &bset->tag_set; 356 set->ops = &bsg_mq_ops, 357 set->nr_hw_queues = 1; 358 set->queue_depth = 128; 359 set->numa_node = NUMA_NO_NODE; 360 set->cmd_size = sizeof(struct bsg_job) + dd_job_size; 361 set->flags = BLK_MQ_F_NO_SCHED | BLK_MQ_F_BLOCKING; 362 if (blk_mq_alloc_tag_set(set)) 363 goto out_tag_set; 364 365 q = blk_mq_init_queue(set); 366 if (IS_ERR(q)) { 367 ret = PTR_ERR(q); 368 goto out_queue; 369 } 370 371 q->queuedata = dev; 372 blk_queue_flag_set(QUEUE_FLAG_BIDI, q); 373 blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT); 374 375 ret = bsg_register_queue(q, dev, name, &bsg_transport_ops); 376 if (ret) { 377 printk(KERN_ERR "%s: bsg interface failed to " 378 "initialize - register queue\n", dev->kobj.name); 379 goto out_cleanup_queue; 380 } 381 382 return q; 383 out_cleanup_queue: 384 blk_cleanup_queue(q); 385 out_queue: 386 blk_mq_free_tag_set(set); 387 out_tag_set: 388 kfree(bset); 389 return ERR_PTR(ret); 390 } 391 EXPORT_SYMBOL_GPL(bsg_setup_queue); 392