[SCSI] host state model update: mediate host add/remove race
[linux-2.6] / 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/string.h>
28 #include <linux/mm.h>
29 #include <linux/init.h>
30 #include <linux/completion.h>
31 #include <linux/transport_class.h>
32
33 #include <scsi/scsi_device.h>
34 #include <scsi/scsi_host.h>
35 #include <scsi/scsi_transport.h>
36
37 #include "scsi_priv.h"
38 #include "scsi_logging.h"
39
40
41 static int scsi_host_next_hn;           /* host_no for next new host */
42
43
44 static void scsi_host_cls_release(struct class_device *class_dev)
45 {
46         put_device(&class_to_shost(class_dev)->shost_gendev);
47 }
48
49 static struct class shost_class = {
50         .name           = "scsi_host",
51         .release        = scsi_host_cls_release,
52 };
53
54 /**
55  *      scsi_host_set_state - Take the given host through the host
56  *              state model.
57  *      @shost: scsi host to change the state of.
58  *      @state: state to change to.
59  *
60  *      Returns zero if unsuccessful or an error if the requested
61  *      transition is illegal.
62  **/
63 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
64 {
65         enum scsi_host_state oldstate = shost->shost_state;
66
67         if (state == oldstate)
68                 return 0;
69
70         switch (state) {
71         case SHOST_CREATED:
72                 /* There are no legal states that come back to
73                  * created.  This is the manually initialised start
74                  * state */
75                 goto illegal;
76
77         case SHOST_RUNNING:
78                 switch (oldstate) {
79                 case SHOST_CREATED:
80                 case SHOST_RECOVERY:
81                         break;
82                 default:
83                         goto illegal;
84                 }
85                 break;
86
87         case SHOST_RECOVERY:
88                 switch (oldstate) {
89                 case SHOST_RUNNING:
90                         break;
91                 default:
92                         goto illegal;
93                 }
94                 break;
95
96         case SHOST_CANCEL:
97                 switch (oldstate) {
98                 case SHOST_CREATED:
99                 case SHOST_RUNNING:
100                         break;
101                 default:
102                         goto illegal;
103                 }
104                 break;
105
106         case SHOST_DEL:
107                 switch (oldstate) {
108                 case SHOST_CANCEL:
109                         break;
110                 default:
111                         goto illegal;
112                 }
113                 break;
114
115         }
116         shost->shost_state = state;
117         return 0;
118
119  illegal:
120         SCSI_LOG_ERROR_RECOVERY(1,
121                                 dev_printk(KERN_ERR, &shost->shost_gendev,
122                                            "Illegal host state transition"
123                                            "%s->%s\n",
124                                            scsi_host_state_name(oldstate),
125                                            scsi_host_state_name(state)));
126         return -EINVAL;
127 }
128 EXPORT_SYMBOL(scsi_host_set_state);
129
130 /**
131  * scsi_remove_host - remove a scsi host
132  * @shost:      a pointer to a scsi host to remove
133  **/
134 void scsi_remove_host(struct Scsi_Host *shost)
135 {
136         down(&shost->scan_mutex);
137         scsi_host_set_state(shost, SHOST_CANCEL);
138         up(&shost->scan_mutex);
139         scsi_forget_host(shost);
140         scsi_proc_host_rm(shost);
141
142         scsi_host_set_state(shost, SHOST_DEL);
143
144         transport_unregister_device(&shost->shost_gendev);
145         class_device_unregister(&shost->shost_classdev);
146         device_del(&shost->shost_gendev);
147 }
148 EXPORT_SYMBOL(scsi_remove_host);
149
150 /**
151  * scsi_add_host - add a scsi host
152  * @shost:      scsi host pointer to add
153  * @dev:        a struct device of type scsi class
154  *
155  * Return value: 
156  *      0 on success / != 0 for error
157  **/
158 int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
159 {
160         struct scsi_host_template *sht = shost->hostt;
161         int error = -EINVAL;
162
163         printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
164                         sht->info ? sht->info(shost) : sht->name);
165
166         if (!shost->can_queue) {
167                 printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
168                                 sht->name);
169                 goto out;
170         }
171
172         if (!shost->shost_gendev.parent)
173                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
174
175         error = device_add(&shost->shost_gendev);
176         if (error)
177                 goto out;
178
179         scsi_host_set_state(shost, SHOST_RUNNING);
180         get_device(shost->shost_gendev.parent);
181
182         error = class_device_add(&shost->shost_classdev);
183         if (error)
184                 goto out_del_gendev;
185
186         get_device(&shost->shost_gendev);
187
188         if (shost->transportt->host_size &&
189             (shost->shost_data = kmalloc(shost->transportt->host_size,
190                                          GFP_KERNEL)) == NULL)
191                 goto out_del_classdev;
192
193         if (shost->transportt->create_work_queue) {
194                 snprintf(shost->work_q_name, KOBJ_NAME_LEN, "scsi_wq_%d",
195                         shost->host_no);
196                 shost->work_q = create_singlethread_workqueue(
197                                         shost->work_q_name);
198                 if (!shost->work_q)
199                         goto out_free_shost_data;
200         }
201
202         error = scsi_sysfs_add_host(shost);
203         if (error)
204                 goto out_destroy_host;
205
206         scsi_proc_host_add(shost);
207         return error;
208
209  out_destroy_host:
210         if (shost->work_q)
211                 destroy_workqueue(shost->work_q);
212  out_free_shost_data:
213         kfree(shost->shost_data);
214  out_del_classdev:
215         class_device_del(&shost->shost_classdev);
216  out_del_gendev:
217         device_del(&shost->shost_gendev);
218  out:
219         return error;
220 }
221 EXPORT_SYMBOL(scsi_add_host);
222
223 static void scsi_host_dev_release(struct device *dev)
224 {
225         struct Scsi_Host *shost = dev_to_shost(dev);
226         struct device *parent = dev->parent;
227
228         if (shost->ehandler) {
229                 DECLARE_COMPLETION(sem);
230                 shost->eh_notify = &sem;
231                 shost->eh_kill = 1;
232                 up(shost->eh_wait);
233                 wait_for_completion(&sem);
234                 shost->eh_notify = NULL;
235         }
236
237         if (shost->work_q)
238                 destroy_workqueue(shost->work_q);
239
240         scsi_proc_hostdir_rm(shost->hostt);
241         scsi_destroy_command_freelist(shost);
242         kfree(shost->shost_data);
243
244         if (parent)
245                 put_device(parent);
246         kfree(shost);
247 }
248
249 /**
250  * scsi_host_alloc - register a scsi host adapter instance.
251  * @sht:        pointer to scsi host template
252  * @privsize:   extra bytes to allocate for driver
253  *
254  * Note:
255  *      Allocate a new Scsi_Host and perform basic initialization.
256  *      The host is not published to the scsi midlayer until scsi_add_host
257  *      is called.
258  *
259  * Return value:
260  *      Pointer to a new Scsi_Host
261  **/
262 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
263 {
264         struct Scsi_Host *shost;
265         int gfp_mask = GFP_KERNEL, rval;
266         DECLARE_COMPLETION(complete);
267
268         if (sht->unchecked_isa_dma && privsize)
269                 gfp_mask |= __GFP_DMA;
270
271         /* Check to see if this host has any error handling facilities */
272         if (!sht->eh_strategy_handler && !sht->eh_abort_handler &&
273             !sht->eh_device_reset_handler && !sht->eh_bus_reset_handler &&
274             !sht->eh_host_reset_handler) {
275                 printk(KERN_ERR "ERROR: SCSI host `%s' has no error handling\n"
276                                 "ERROR: This is not a safe way to run your "
277                                         "SCSI host\n"
278                                 "ERROR: The error handling must be added to "
279                                 "this driver\n", sht->proc_name);
280                 dump_stack();
281         }
282
283         shost = kmalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
284         if (!shost)
285                 return NULL;
286         memset(shost, 0, sizeof(struct Scsi_Host) + privsize);
287
288         spin_lock_init(&shost->default_lock);
289         scsi_assign_lock(shost, &shost->default_lock);
290         shost->shost_state = SHOST_CREATED;
291         INIT_LIST_HEAD(&shost->__devices);
292         INIT_LIST_HEAD(&shost->__targets);
293         INIT_LIST_HEAD(&shost->eh_cmd_q);
294         INIT_LIST_HEAD(&shost->starved_list);
295         init_waitqueue_head(&shost->host_wait);
296
297         init_MUTEX(&shost->scan_mutex);
298
299         shost->host_no = scsi_host_next_hn++; /* XXX(hch): still racy */
300         shost->dma_channel = 0xff;
301
302         /* These three are default values which can be overridden */
303         shost->max_channel = 0;
304         shost->max_id = 8;
305         shost->max_lun = 8;
306
307         /* Give each shost a default transportt */
308         shost->transportt = &blank_transport_template;
309
310         /*
311          * All drivers right now should be able to handle 12 byte
312          * commands.  Every so often there are requests for 16 byte
313          * commands, but individual low-level drivers need to certify that
314          * they actually do something sensible with such commands.
315          */
316         shost->max_cmd_len = 12;
317         shost->hostt = sht;
318         shost->this_id = sht->this_id;
319         shost->can_queue = sht->can_queue;
320         shost->sg_tablesize = sht->sg_tablesize;
321         shost->cmd_per_lun = sht->cmd_per_lun;
322         shost->unchecked_isa_dma = sht->unchecked_isa_dma;
323         shost->use_clustering = sht->use_clustering;
324         shost->ordered_flush = sht->ordered_flush;
325         shost->ordered_tag = sht->ordered_tag;
326
327         /*
328          * hosts/devices that do queueing must support ordered tags
329          */
330         if (shost->can_queue > 1 && shost->ordered_flush) {
331                 printk(KERN_ERR "scsi: ordered flushes don't support queueing\n");
332                 shost->ordered_flush = 0;
333         }
334
335         if (sht->max_host_blocked)
336                 shost->max_host_blocked = sht->max_host_blocked;
337         else
338                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
339
340         /*
341          * If the driver imposes no hard sector transfer limit, start at
342          * machine infinity initially.
343          */
344         if (sht->max_sectors)
345                 shost->max_sectors = sht->max_sectors;
346         else
347                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
348
349         /*
350          * assume a 4GB boundary, if not set
351          */
352         if (sht->dma_boundary)
353                 shost->dma_boundary = sht->dma_boundary;
354         else
355                 shost->dma_boundary = 0xffffffff;
356
357         rval = scsi_setup_command_freelist(shost);
358         if (rval)
359                 goto fail_kfree;
360
361         device_initialize(&shost->shost_gendev);
362         snprintf(shost->shost_gendev.bus_id, BUS_ID_SIZE, "host%d",
363                 shost->host_no);
364         shost->shost_gendev.release = scsi_host_dev_release;
365
366         class_device_initialize(&shost->shost_classdev);
367         shost->shost_classdev.dev = &shost->shost_gendev;
368         shost->shost_classdev.class = &shost_class;
369         snprintf(shost->shost_classdev.class_id, BUS_ID_SIZE, "host%d",
370                   shost->host_no);
371
372         shost->eh_notify = &complete;
373         rval = kernel_thread(scsi_error_handler, shost, 0);
374         if (rval < 0)
375                 goto fail_destroy_freelist;
376         wait_for_completion(&complete);
377         shost->eh_notify = NULL;
378
379         scsi_proc_hostdir_add(shost->hostt);
380         return shost;
381
382  fail_destroy_freelist:
383         scsi_destroy_command_freelist(shost);
384  fail_kfree:
385         kfree(shost);
386         return NULL;
387 }
388 EXPORT_SYMBOL(scsi_host_alloc);
389
390 struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
391 {
392         struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
393
394         if (!sht->detect) {
395                 printk(KERN_WARNING "scsi_register() called on new-style "
396                                     "template for driver %s\n", sht->name);
397                 dump_stack();
398         }
399
400         if (shost)
401                 list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
402         return shost;
403 }
404 EXPORT_SYMBOL(scsi_register);
405
406 void scsi_unregister(struct Scsi_Host *shost)
407 {
408         list_del(&shost->sht_legacy_list);
409         scsi_host_put(shost);
410 }
411 EXPORT_SYMBOL(scsi_unregister);
412
413 /**
414  * scsi_host_lookup - get a reference to a Scsi_Host by host no
415  *
416  * @hostnum:    host number to locate
417  *
418  * Return value:
419  *      A pointer to located Scsi_Host or NULL.
420  **/
421 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
422 {
423         struct class *class = &shost_class;
424         struct class_device *cdev;
425         struct Scsi_Host *shost = ERR_PTR(-ENXIO), *p;
426
427         down_read(&class->subsys.rwsem);
428         list_for_each_entry(cdev, &class->children, node) {
429                 p = class_to_shost(cdev);
430                 if (p->host_no == hostnum) {
431                         shost = scsi_host_get(p);
432                         break;
433                 }
434         }
435         up_read(&class->subsys.rwsem);
436
437         return shost;
438 }
439 EXPORT_SYMBOL(scsi_host_lookup);
440
441 /**
442  * scsi_host_get - inc a Scsi_Host ref count
443  * @shost:      Pointer to Scsi_Host to inc.
444  **/
445 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
446 {
447         if ((shost->shost_state == SHOST_DEL) ||
448                 !get_device(&shost->shost_gendev))
449                 return NULL;
450         return shost;
451 }
452 EXPORT_SYMBOL(scsi_host_get);
453
454 /**
455  * scsi_host_put - dec a Scsi_Host ref count
456  * @shost:      Pointer to Scsi_Host to dec.
457  **/
458 void scsi_host_put(struct Scsi_Host *shost)
459 {
460         put_device(&shost->shost_gendev);
461 }
462 EXPORT_SYMBOL(scsi_host_put);
463
464 int scsi_init_hosts(void)
465 {
466         return class_register(&shost_class);
467 }
468
469 void scsi_exit_hosts(void)
470 {
471         class_unregister(&shost_class);
472 }
473
474 int scsi_is_host_device(const struct device *dev)
475 {
476         return dev->release == scsi_host_dev_release;
477 }
478 EXPORT_SYMBOL(scsi_is_host_device);
479
480 /**
481  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
482  * @shost:      Pointer to Scsi_Host.
483  * @work:       Work to queue for execution.
484  *
485  * Return value:
486  *      0 on success / != 0 for error
487  **/
488 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
489 {
490         if (unlikely(!shost->work_q)) {
491                 printk(KERN_ERR
492                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
493                         "when no workqueue created.\n", shost->hostt->name);
494                 dump_stack();
495
496                 return -EINVAL;
497         }
498
499         return queue_work(shost->work_q, work);
500 }
501 EXPORT_SYMBOL_GPL(scsi_queue_work);
502
503 /**
504  * scsi_flush_work - Flush a Scsi_Host's workqueue.
505  * @shost:      Pointer to Scsi_Host.
506  **/
507 void scsi_flush_work(struct Scsi_Host *shost)
508 {
509         if (!shost->work_q) {
510                 printk(KERN_ERR
511                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
512                         "when no workqueue created.\n", shost->hostt->name);
513                 dump_stack();
514                 return;
515         }
516
517         flush_workqueue(shost->work_q);
518 }
519 EXPORT_SYMBOL_GPL(scsi_flush_work);