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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  */
35 static void bsg_destroy_job(struct kref *kref)
36 {
37         struct bsg_job *job = container_of(kref, struct bsg_job, kref);
38         struct request *rq = job->req;
39
40         blk_end_request_all(rq, rq->errors);
41
42         put_device(job->dev);   /* release reference for the request */
43
44         kfree(job->request_payload.sg_list);
45         kfree(job->reply_payload.sg_list);
46         kfree(job);
47 }
48
49 void bsg_job_put(struct bsg_job *job)
50 {
51         kref_put(&job->kref, bsg_destroy_job);
52 }
53 EXPORT_SYMBOL_GPL(bsg_job_put);
54
55 int bsg_job_get(struct bsg_job *job)
56 {
57         return kref_get_unless_zero(&job->kref);
58 }
59 EXPORT_SYMBOL_GPL(bsg_job_get);
60
61 /**
62  * bsg_job_done - completion routine for bsg requests
63  * @job: bsg_job that is complete
64  * @result: job reply result
65  * @reply_payload_rcv_len: length of payload recvd
66  *
67  * The LLD should call this when the bsg job has completed.
68  */
69 void bsg_job_done(struct bsg_job *job, int result,
70                   unsigned int reply_payload_rcv_len)
71 {
72         struct request *req = job->req;
73         struct request *rsp = req->next_rq;
74         struct scsi_request *rq = scsi_req(req);
75         int err;
76
77         err = job->req->errors = result;
78         if (err < 0)
79                 /* we're only returning the result field in the reply */
80                 rq->sense_len = sizeof(u32);
81         else
82                 rq->sense_len = job->reply_len;
83         /* we assume all request payload was transferred, residual == 0 */
84         rq->resid_len = 0;
85
86         if (rsp) {
87                 WARN_ON(reply_payload_rcv_len > scsi_req(rsp)->resid_len);
88
89                 /* set reply (bidi) residual */
90                 scsi_req(rsp)->resid_len -=
91                         min(reply_payload_rcv_len, scsi_req(rsp)->resid_len);
92         }
93         blk_complete_request(req);
94 }
95 EXPORT_SYMBOL_GPL(bsg_job_done);
96
97 /**
98  * bsg_softirq_done - softirq done routine for destroying the bsg requests
99  * @rq: BSG request that holds the job to be destroyed
100  */
101 static void bsg_softirq_done(struct request *rq)
102 {
103         struct bsg_job *job = rq->special;
104
105         bsg_job_put(job);
106 }
107
108 static int bsg_map_buffer(struct bsg_buffer *buf, struct request *req)
109 {
110         size_t sz = (sizeof(struct scatterlist) * req->nr_phys_segments);
111
112         BUG_ON(!req->nr_phys_segments);
113
114         buf->sg_list = kzalloc(sz, GFP_KERNEL);
115         if (!buf->sg_list)
116                 return -ENOMEM;
117         sg_init_table(buf->sg_list, req->nr_phys_segments);
118         scsi_req(req)->resid_len = blk_rq_bytes(req);
119         buf->sg_cnt = blk_rq_map_sg(req->q, req, buf->sg_list);
120         buf->payload_len = blk_rq_bytes(req);
121         return 0;
122 }
123
124 /**
125  * bsg_create_job - create the bsg_job structure for the bsg request
126  * @dev: device that is being sent the bsg request
127  * @req: BSG request that needs a job structure
128  */
129 static int bsg_create_job(struct device *dev, struct request *req)
130 {
131         struct request *rsp = req->next_rq;
132         struct request_queue *q = req->q;
133         struct scsi_request *rq = scsi_req(req);
134         struct bsg_job *job;
135         int ret;
136
137         BUG_ON(req->special);
138
139         job = kzalloc(sizeof(struct bsg_job) + q->bsg_job_size, GFP_KERNEL);
140         if (!job)
141                 return -ENOMEM;
142
143         req->special = job;
144         job->req = req;
145         if (q->bsg_job_size)
146                 job->dd_data = (void *)&job[1];
147         job->request = rq->cmd;
148         job->request_len = rq->cmd_len;
149         job->reply = rq->sense;
150         job->reply_len = SCSI_SENSE_BUFFERSIZE; /* Size of sense buffer
151                                                  * allocated */
152         if (req->bio) {
153                 ret = bsg_map_buffer(&job->request_payload, req);
154                 if (ret)
155                         goto failjob_rls_job;
156         }
157         if (rsp && rsp->bio) {
158                 ret = bsg_map_buffer(&job->reply_payload, rsp);
159                 if (ret)
160                         goto failjob_rls_rqst_payload;
161         }
162         job->dev = dev;
163         /* take a reference for the request */
164         get_device(job->dev);
165         kref_init(&job->kref);
166         return 0;
167
168 failjob_rls_rqst_payload:
169         kfree(job->request_payload.sg_list);
170 failjob_rls_job:
171         kfree(job);
172         return -ENOMEM;
173 }
174
175 /**
176  * bsg_request_fn - generic handler for bsg requests
177  * @q: request queue to manage
178  *
179  * On error the create_bsg_job function should return a -Exyz error value
180  * that will be set to the req->errors.
181  *
182  * Drivers/subsys should pass this to the queue init function.
183  */
184 static void bsg_request_fn(struct request_queue *q)
185         __releases(q->queue_lock)
186         __acquires(q->queue_lock)
187 {
188         struct device *dev = q->queuedata;
189         struct request *req;
190         struct bsg_job *job;
191         int ret;
192
193         if (!get_device(dev))
194                 return;
195
196         while (1) {
197                 req = blk_fetch_request(q);
198                 if (!req)
199                         break;
200                 spin_unlock_irq(q->queue_lock);
201
202                 ret = bsg_create_job(dev, req);
203                 if (ret) {
204                         req->errors = ret;
205                         blk_end_request_all(req, ret);
206                         spin_lock_irq(q->queue_lock);
207                         continue;
208                 }
209
210                 job = req->special;
211                 ret = q->bsg_job_fn(job);
212                 spin_lock_irq(q->queue_lock);
213                 if (ret)
214                         break;
215         }
216
217         spin_unlock_irq(q->queue_lock);
218         put_device(dev);
219         spin_lock_irq(q->queue_lock);
220 }
221
222 /**
223  * bsg_setup_queue - Create and add the bsg hooks so we can receive requests
224  * @dev: device to attach bsg device to
225  * @name: device to give bsg device
226  * @job_fn: bsg job handler
227  * @dd_job_size: size of LLD data needed for each job
228  */
229 struct request_queue *bsg_setup_queue(struct device *dev, char *name,
230                 bsg_job_fn *job_fn, int dd_job_size)
231 {
232         struct request_queue *q;
233         int ret;
234
235         q = blk_alloc_queue(GFP_KERNEL);
236         if (!q)
237                 return ERR_PTR(-ENOMEM);
238         q->cmd_size = sizeof(struct scsi_request);
239         q->request_fn = bsg_request_fn;
240
241         ret = blk_init_allocated_queue(q);
242         if (ret)
243                 goto out_cleanup_queue;
244
245         q->queuedata = dev;
246         q->bsg_job_size = dd_job_size;
247         q->bsg_job_fn = job_fn;
248         queue_flag_set_unlocked(QUEUE_FLAG_BIDI, q);
249         blk_queue_softirq_done(q, bsg_softirq_done);
250         blk_queue_rq_timeout(q, BLK_DEFAULT_SG_TIMEOUT);
251
252         ret = bsg_register_queue(q, dev, name, NULL);
253         if (ret) {
254                 printk(KERN_ERR "%s: bsg interface failed to "
255                        "initialize - register queue\n", dev->kobj.name);
256                 goto out_cleanup_queue;
257         }
258
259         return q;
260 out_cleanup_queue:
261         blk_cleanup_queue(q);
262         return ERR_PTR(ret);
263 }
264 EXPORT_SYMBOL_GPL(bsg_setup_queue);