Fix device removal NULL pointer dereference
[pandora-kernel.git] / drivers / scsi / hosts.c
1 /*
2  *  hosts.c Copyright (C) 1992 Drew Eckhardt
3  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
4  *          Copyright (C) 2002-2003 Christoph Hellwig
5  *
6  *  mid to lowlevel SCSI driver interface
7  *      Initial versions: Drew Eckhardt
8  *      Subsequent revisions: Eric Youngdale
9  *
10  *  <drew@colorado.edu>
11  *
12  *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
13  *  Added QLOGIC QLA1280 SCSI controller kernel host support. 
14  *     August 4, 1999 Fred Lewis, Intel DuPont
15  *
16  *  Updated to reflect the new initialization scheme for the higher 
17  *  level of scsi drivers (sd/sr/st)
18  *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
19  *
20  *  Restructured scsi_host lists and associated functions.
21  *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
22  */
23
24 #include <linux/module.h>
25 #include <linux/blkdev.h>
26 #include <linux/kernel.h>
27 #include <linux/slab.h>
28 #include <linux/kthread.h>
29 #include <linux/string.h>
30 #include <linux/mm.h>
31 #include <linux/init.h>
32 #include <linux/completion.h>
33 #include <linux/transport_class.h>
34 #include <linux/platform_device.h>
35 #include <linux/pm_runtime.h>
36
37 #include <scsi/scsi_device.h>
38 #include <scsi/scsi_host.h>
39 #include <scsi/scsi_transport.h>
40
41 #include "scsi_priv.h"
42 #include "scsi_logging.h"
43
44
45 static atomic_t scsi_host_next_hn;      /* host_no for next new host */
46
47
48 static void scsi_host_cls_release(struct device *dev)
49 {
50         put_device(&class_to_shost(dev)->shost_gendev);
51 }
52
53 static struct class shost_class = {
54         .name           = "scsi_host",
55         .dev_release    = scsi_host_cls_release,
56 };
57
58 /**
59  *      scsi_host_set_state - Take the given host through the host state model.
60  *      @shost: scsi host to change the state of.
61  *      @state: state to change to.
62  *
63  *      Returns zero if unsuccessful or an error if the requested
64  *      transition is illegal.
65  **/
66 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
67 {
68         enum scsi_host_state oldstate = shost->shost_state;
69
70         if (state == oldstate)
71                 return 0;
72
73         switch (state) {
74         case SHOST_CREATED:
75                 /* There are no legal states that come back to
76                  * created.  This is the manually initialised start
77                  * state */
78                 goto illegal;
79
80         case SHOST_RUNNING:
81                 switch (oldstate) {
82                 case SHOST_CREATED:
83                 case SHOST_RECOVERY:
84                         break;
85                 default:
86                         goto illegal;
87                 }
88                 break;
89
90         case SHOST_RECOVERY:
91                 switch (oldstate) {
92                 case SHOST_RUNNING:
93                         break;
94                 default:
95                         goto illegal;
96                 }
97                 break;
98
99         case SHOST_CANCEL:
100                 switch (oldstate) {
101                 case SHOST_CREATED:
102                 case SHOST_RUNNING:
103                 case SHOST_CANCEL_RECOVERY:
104                         break;
105                 default:
106                         goto illegal;
107                 }
108                 break;
109
110         case SHOST_DEL:
111                 switch (oldstate) {
112                 case SHOST_CANCEL:
113                 case SHOST_DEL_RECOVERY:
114                         break;
115                 default:
116                         goto illegal;
117                 }
118                 break;
119
120         case SHOST_CANCEL_RECOVERY:
121                 switch (oldstate) {
122                 case SHOST_CANCEL:
123                 case SHOST_RECOVERY:
124                         break;
125                 default:
126                         goto illegal;
127                 }
128                 break;
129
130         case SHOST_DEL_RECOVERY:
131                 switch (oldstate) {
132                 case SHOST_CANCEL_RECOVERY:
133                         break;
134                 default:
135                         goto illegal;
136                 }
137                 break;
138         }
139         shost->shost_state = state;
140         return 0;
141
142  illegal:
143         SCSI_LOG_ERROR_RECOVERY(1,
144                                 shost_printk(KERN_ERR, shost,
145                                              "Illegal host state transition"
146                                              "%s->%s\n",
147                                              scsi_host_state_name(oldstate),
148                                              scsi_host_state_name(state)));
149         return -EINVAL;
150 }
151 EXPORT_SYMBOL(scsi_host_set_state);
152
153 /**
154  * scsi_remove_host - remove a scsi host
155  * @shost:      a pointer to a scsi host to remove
156  **/
157 void scsi_remove_host(struct Scsi_Host *shost)
158 {
159         unsigned long flags;
160
161         mutex_lock(&shost->scan_mutex);
162         spin_lock_irqsave(shost->host_lock, flags);
163         if (scsi_host_set_state(shost, SHOST_CANCEL))
164                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
165                         spin_unlock_irqrestore(shost->host_lock, flags);
166                         mutex_unlock(&shost->scan_mutex);
167                         return;
168                 }
169         spin_unlock_irqrestore(shost->host_lock, flags);
170
171         scsi_autopm_get_host(shost);
172         scsi_forget_host(shost);
173         mutex_unlock(&shost->scan_mutex);
174         scsi_proc_host_rm(shost);
175
176         spin_lock_irqsave(shost->host_lock, flags);
177         if (scsi_host_set_state(shost, SHOST_DEL))
178                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
179         spin_unlock_irqrestore(shost->host_lock, flags);
180
181         transport_unregister_device(&shost->shost_gendev);
182         device_unregister(&shost->shost_dev);
183         device_del(&shost->shost_gendev);
184 }
185 EXPORT_SYMBOL(scsi_remove_host);
186
187 /**
188  * scsi_add_host_with_dma - add a scsi host with dma device
189  * @shost:      scsi host pointer to add
190  * @dev:        a struct device of type scsi class
191  * @dma_dev:    dma device for the host
192  *
193  * Note: You rarely need to worry about this unless you're in a
194  * virtualised host environments, so use the simpler scsi_add_host()
195  * function instead.
196  *
197  * Return value: 
198  *      0 on success / != 0 for error
199  **/
200 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
201                            struct device *dma_dev)
202 {
203         struct scsi_host_template *sht = shost->hostt;
204         int error = -EINVAL;
205
206         printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
207                         sht->info ? sht->info(shost) : sht->name);
208
209         if (!shost->can_queue) {
210                 printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
211                                 sht->name);
212                 goto fail;
213         }
214
215         error = scsi_setup_command_freelist(shost);
216         if (error)
217                 goto fail;
218
219         if (!shost->shost_gendev.parent)
220                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
221         shost->dma_dev = dma_dev;
222
223         error = device_add(&shost->shost_gendev);
224         if (error)
225                 goto out;
226
227         pm_runtime_set_active(&shost->shost_gendev);
228         pm_runtime_enable(&shost->shost_gendev);
229         device_enable_async_suspend(&shost->shost_gendev);
230
231         scsi_host_set_state(shost, SHOST_RUNNING);
232         get_device(shost->shost_gendev.parent);
233
234         device_enable_async_suspend(&shost->shost_dev);
235
236         error = device_add(&shost->shost_dev);
237         if (error)
238                 goto out_del_gendev;
239
240         get_device(&shost->shost_gendev);
241
242         if (shost->transportt->host_size) {
243                 shost->shost_data = kzalloc(shost->transportt->host_size,
244                                          GFP_KERNEL);
245                 if (shost->shost_data == NULL) {
246                         error = -ENOMEM;
247                         goto out_del_dev;
248                 }
249         }
250
251         if (shost->transportt->create_work_queue) {
252                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
253                          "scsi_wq_%d", shost->host_no);
254                 shost->work_q = create_singlethread_workqueue(
255                                         shost->work_q_name);
256                 if (!shost->work_q) {
257                         error = -EINVAL;
258                         goto out_free_shost_data;
259                 }
260         }
261
262         error = scsi_sysfs_add_host(shost);
263         if (error)
264                 goto out_destroy_host;
265
266         scsi_proc_host_add(shost);
267         return error;
268
269  out_destroy_host:
270         if (shost->work_q)
271                 destroy_workqueue(shost->work_q);
272  out_free_shost_data:
273         kfree(shost->shost_data);
274  out_del_dev:
275         device_del(&shost->shost_dev);
276  out_del_gendev:
277         device_del(&shost->shost_gendev);
278  out:
279         scsi_destroy_command_freelist(shost);
280  fail:
281         return error;
282 }
283 EXPORT_SYMBOL(scsi_add_host_with_dma);
284
285 static void scsi_host_dev_release(struct device *dev)
286 {
287         struct Scsi_Host *shost = dev_to_shost(dev);
288         struct device *parent = dev->parent;
289         struct request_queue *q;
290         void *queuedata;
291
292         scsi_proc_hostdir_rm(shost->hostt);
293
294         if (shost->ehandler)
295                 kthread_stop(shost->ehandler);
296         if (shost->work_q)
297                 destroy_workqueue(shost->work_q);
298         q = shost->uspace_req_q;
299         if (q) {
300                 queuedata = q->queuedata;
301                 blk_cleanup_queue(q);
302                 kfree(queuedata);
303         }
304
305         scsi_destroy_command_freelist(shost);
306         if (shost->bqt)
307                 blk_free_tags(shost->bqt);
308
309         kfree(shost->shost_data);
310
311         if (parent)
312                 put_device(parent);
313         kfree(shost);
314 }
315
316 static struct device_type scsi_host_type = {
317         .name =         "scsi_host",
318         .release =      scsi_host_dev_release,
319 };
320
321 /**
322  * scsi_host_alloc - register a scsi host adapter instance.
323  * @sht:        pointer to scsi host template
324  * @privsize:   extra bytes to allocate for driver
325  *
326  * Note:
327  *      Allocate a new Scsi_Host and perform basic initialization.
328  *      The host is not published to the scsi midlayer until scsi_add_host
329  *      is called.
330  *
331  * Return value:
332  *      Pointer to a new Scsi_Host
333  **/
334 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
335 {
336         struct Scsi_Host *shost;
337         gfp_t gfp_mask = GFP_KERNEL;
338
339         if (sht->unchecked_isa_dma && privsize)
340                 gfp_mask |= __GFP_DMA;
341
342         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
343         if (!shost)
344                 return NULL;
345
346         shost->host_lock = &shost->default_lock;
347         spin_lock_init(shost->host_lock);
348         shost->shost_state = SHOST_CREATED;
349         INIT_LIST_HEAD(&shost->__devices);
350         INIT_LIST_HEAD(&shost->__targets);
351         INIT_LIST_HEAD(&shost->eh_cmd_q);
352         INIT_LIST_HEAD(&shost->starved_list);
353         init_waitqueue_head(&shost->host_wait);
354
355         mutex_init(&shost->scan_mutex);
356
357         /*
358          * subtract one because we increment first then return, but we need to
359          * know what the next host number was before increment
360          */
361         shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;
362         shost->dma_channel = 0xff;
363
364         /* These three are default values which can be overridden */
365         shost->max_channel = 0;
366         shost->max_id = 8;
367         shost->max_lun = 8;
368
369         /* Give each shost a default transportt */
370         shost->transportt = &blank_transport_template;
371
372         /*
373          * All drivers right now should be able to handle 12 byte
374          * commands.  Every so often there are requests for 16 byte
375          * commands, but individual low-level drivers need to certify that
376          * they actually do something sensible with such commands.
377          */
378         shost->max_cmd_len = 12;
379         shost->hostt = sht;
380         shost->this_id = sht->this_id;
381         shost->can_queue = sht->can_queue;
382         shost->sg_tablesize = sht->sg_tablesize;
383         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
384         shost->cmd_per_lun = sht->cmd_per_lun;
385         shost->unchecked_isa_dma = sht->unchecked_isa_dma;
386         shost->use_clustering = sht->use_clustering;
387         shost->ordered_tag = sht->ordered_tag;
388
389         if (sht->supported_mode == MODE_UNKNOWN)
390                 /* means we didn't set it ... default to INITIATOR */
391                 shost->active_mode = MODE_INITIATOR;
392         else
393                 shost->active_mode = sht->supported_mode;
394
395         if (sht->max_host_blocked)
396                 shost->max_host_blocked = sht->max_host_blocked;
397         else
398                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
399
400         /*
401          * If the driver imposes no hard sector transfer limit, start at
402          * machine infinity initially.
403          */
404         if (sht->max_sectors)
405                 shost->max_sectors = sht->max_sectors;
406         else
407                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
408
409         /*
410          * assume a 4GB boundary, if not set
411          */
412         if (sht->dma_boundary)
413                 shost->dma_boundary = sht->dma_boundary;
414         else
415                 shost->dma_boundary = 0xffffffff;
416
417         device_initialize(&shost->shost_gendev);
418         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
419         shost->shost_gendev.bus = &scsi_bus_type;
420         shost->shost_gendev.type = &scsi_host_type;
421
422         device_initialize(&shost->shost_dev);
423         shost->shost_dev.parent = &shost->shost_gendev;
424         shost->shost_dev.class = &shost_class;
425         dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
426         shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;
427
428         shost->ehandler = kthread_run(scsi_error_handler, shost,
429                         "scsi_eh_%d", shost->host_no);
430         if (IS_ERR(shost->ehandler)) {
431                 printk(KERN_WARNING "scsi%d: error handler thread failed to spawn, error = %ld\n",
432                         shost->host_no, PTR_ERR(shost->ehandler));
433                 goto fail_kfree;
434         }
435
436         scsi_proc_hostdir_add(shost->hostt);
437         return shost;
438
439  fail_kfree:
440         kfree(shost);
441         return NULL;
442 }
443 EXPORT_SYMBOL(scsi_host_alloc);
444
445 struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
446 {
447         struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
448
449         if (!sht->detect) {
450                 printk(KERN_WARNING "scsi_register() called on new-style "
451                                     "template for driver %s\n", sht->name);
452                 dump_stack();
453         }
454
455         if (shost)
456                 list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
457         return shost;
458 }
459 EXPORT_SYMBOL(scsi_register);
460
461 void scsi_unregister(struct Scsi_Host *shost)
462 {
463         list_del(&shost->sht_legacy_list);
464         scsi_host_put(shost);
465 }
466 EXPORT_SYMBOL(scsi_unregister);
467
468 static int __scsi_host_match(struct device *dev, void *data)
469 {
470         struct Scsi_Host *p;
471         unsigned short *hostnum = (unsigned short *)data;
472
473         p = class_to_shost(dev);
474         return p->host_no == *hostnum;
475 }
476
477 /**
478  * scsi_host_lookup - get a reference to a Scsi_Host by host no
479  * @hostnum:    host number to locate
480  *
481  * Return value:
482  *      A pointer to located Scsi_Host or NULL.
483  *
484  *      The caller must do a scsi_host_put() to drop the reference
485  *      that scsi_host_get() took. The put_device() below dropped
486  *      the reference from class_find_device().
487  **/
488 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
489 {
490         struct device *cdev;
491         struct Scsi_Host *shost = NULL;
492
493         cdev = class_find_device(&shost_class, NULL, &hostnum,
494                                  __scsi_host_match);
495         if (cdev) {
496                 shost = scsi_host_get(class_to_shost(cdev));
497                 put_device(cdev);
498         }
499         return shost;
500 }
501 EXPORT_SYMBOL(scsi_host_lookup);
502
503 /**
504  * scsi_host_get - inc a Scsi_Host ref count
505  * @shost:      Pointer to Scsi_Host to inc.
506  **/
507 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
508 {
509         if ((shost->shost_state == SHOST_DEL) ||
510                 !get_device(&shost->shost_gendev))
511                 return NULL;
512         return shost;
513 }
514 EXPORT_SYMBOL(scsi_host_get);
515
516 /**
517  * scsi_host_put - dec a Scsi_Host ref count
518  * @shost:      Pointer to Scsi_Host to dec.
519  **/
520 void scsi_host_put(struct Scsi_Host *shost)
521 {
522         put_device(&shost->shost_gendev);
523 }
524 EXPORT_SYMBOL(scsi_host_put);
525
526 int scsi_init_hosts(void)
527 {
528         return class_register(&shost_class);
529 }
530
531 void scsi_exit_hosts(void)
532 {
533         class_unregister(&shost_class);
534 }
535
536 int scsi_is_host_device(const struct device *dev)
537 {
538         return dev->type == &scsi_host_type;
539 }
540 EXPORT_SYMBOL(scsi_is_host_device);
541
542 /**
543  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
544  * @shost:      Pointer to Scsi_Host.
545  * @work:       Work to queue for execution.
546  *
547  * Return value:
548  *      1 - work queued for execution
549  *      0 - work is already queued
550  *      -EINVAL - work queue doesn't exist
551  **/
552 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
553 {
554         if (unlikely(!shost->work_q)) {
555                 printk(KERN_ERR
556                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
557                         "when no workqueue created.\n", shost->hostt->name);
558                 dump_stack();
559
560                 return -EINVAL;
561         }
562
563         return queue_work(shost->work_q, work);
564 }
565 EXPORT_SYMBOL_GPL(scsi_queue_work);
566
567 /**
568  * scsi_flush_work - Flush a Scsi_Host's workqueue.
569  * @shost:      Pointer to Scsi_Host.
570  **/
571 void scsi_flush_work(struct Scsi_Host *shost)
572 {
573         if (!shost->work_q) {
574                 printk(KERN_ERR
575                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
576                         "when no workqueue created.\n", shost->hostt->name);
577                 dump_stack();
578                 return;
579         }
580
581         flush_workqueue(shost->work_q);
582 }
583 EXPORT_SYMBOL_GPL(scsi_flush_work);