1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Character device driver for extended error reporting.
4 *
5 * Copyright IBM Corp. 2005
6 * extended error reporting for DASD ECKD devices
7 * Author(s): Stefan Weinhuber <wein@de.ibm.com>
8 */
9
10 #include <linux/init.h>
11 #include <linux/fs.h>
12 #include <linux/kernel.h>
13 #include <linux/miscdevice.h>
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/device.h>
17 #include <linux/poll.h>
18 #include <linux/mutex.h>
19 #include <linux/err.h>
20 #include <linux/slab.h>
21
22 #include <linux/uaccess.h>
23 #include <linux/atomic.h>
24 #include <asm/ebcdic.h>
25
26 #include "dasd_int.h"
27 #include "dasd_eckd.h"
28
29 /*
30 * SECTION: the internal buffer
31 */
32
33 /*
34 * The internal buffer is meant to store obaque blobs of data, so it does
35 * not know of higher level concepts like triggers.
36 * It consists of a number of pages that are used as a ringbuffer. Each data
37 * blob is stored in a simple record that consists of an integer, which
38 * contains the size of the following data, and the data bytes themselfes.
39 *
40 * To allow for multiple independent readers we create one internal buffer
41 * each time the device is opened and destroy the buffer when the file is
42 * closed again. The number of pages used for this buffer is determined by
43 * the module parmeter eer_pages.
44 *
45 * One record can be written to a buffer by using the functions
46 * - dasd_eer_start_record (one time per record to write the size to the
47 * buffer and reserve the space for the data)
48 * - dasd_eer_write_buffer (one or more times per record to write the data)
49 * The data can be written in several steps but you will have to compute
50 * the total size up front for the invocation of dasd_eer_start_record.
51 * If the ringbuffer is full, dasd_eer_start_record will remove the required
52 * number of old records.
53 *
54 * A record is typically read in two steps, first read the integer that
55 * specifies the size of the following data, then read the data.
56 * Both can be done by
57 * - dasd_eer_read_buffer
58 *
59 * For all mentioned functions you need to get the bufferlock first and keep
60 * it until a complete record is written or read.
61 *
62 * All information necessary to keep track of an internal buffer is kept in
63 * a struct eerbuffer. The buffer specific to a file pointer is strored in
64 * the private_data field of that file. To be able to write data to all
65 * existing buffers, each buffer is also added to the bufferlist.
66 * If the user does not want to read a complete record in one go, we have to
67 * keep track of the rest of the record. residual stores the number of bytes
68 * that are still to deliver. If the rest of the record is invalidated between
69 * two reads then residual will be set to -1 so that the next read will fail.
70 * All entries in the eerbuffer structure are protected with the bufferlock.
71 * To avoid races between writing to a buffer on the one side and creating
72 * and destroying buffers on the other side, the bufferlock must also be used
73 * to protect the bufferlist.
74 */
75
76 static int eer_pages = 5;
77 module_param(eer_pages, int, S_IRUGO|S_IWUSR);
78
79 struct eerbuffer {
80 struct list_head list;
81 char **buffer;
82 int buffersize;
83 int buffer_page_count;
84 int head;
85 int tail;
86 int residual;
87 };
88
89 static LIST_HEAD(bufferlist);
90 static DEFINE_SPINLOCK(bufferlock);
91 static DECLARE_WAIT_QUEUE_HEAD(dasd_eer_read_wait_queue);
92
93 /*
94 * How many free bytes are available on the buffer.
95 * Needs to be called with bufferlock held.
96 */
dasd_eer_get_free_bytes(struct eerbuffer * eerb)97 static int dasd_eer_get_free_bytes(struct eerbuffer *eerb)
98 {
99 if (eerb->head < eerb->tail)
100 return eerb->tail - eerb->head - 1;
101 return eerb->buffersize - eerb->head + eerb->tail -1;
102 }
103
104 /*
105 * How many bytes of buffer space are used.
106 * Needs to be called with bufferlock held.
107 */
dasd_eer_get_filled_bytes(struct eerbuffer * eerb)108 static int dasd_eer_get_filled_bytes(struct eerbuffer *eerb)
109 {
110
111 if (eerb->head >= eerb->tail)
112 return eerb->head - eerb->tail;
113 return eerb->buffersize - eerb->tail + eerb->head;
114 }
115
116 /*
117 * The dasd_eer_write_buffer function just copies count bytes of data
118 * to the buffer. Make sure to call dasd_eer_start_record first, to
119 * make sure that enough free space is available.
120 * Needs to be called with bufferlock held.
121 */
dasd_eer_write_buffer(struct eerbuffer * eerb,char * data,int count)122 static void dasd_eer_write_buffer(struct eerbuffer *eerb,
123 char *data, int count)
124 {
125
126 unsigned long headindex,localhead;
127 unsigned long rest, len;
128 char *nextdata;
129
130 nextdata = data;
131 rest = count;
132 while (rest > 0) {
133 headindex = eerb->head / PAGE_SIZE;
134 localhead = eerb->head % PAGE_SIZE;
135 len = min(rest, PAGE_SIZE - localhead);
136 memcpy(eerb->buffer[headindex]+localhead, nextdata, len);
137 nextdata += len;
138 rest -= len;
139 eerb->head += len;
140 if (eerb->head == eerb->buffersize)
141 eerb->head = 0; /* wrap around */
142 BUG_ON(eerb->head > eerb->buffersize);
143 }
144 }
145
146 /*
147 * Needs to be called with bufferlock held.
148 */
dasd_eer_read_buffer(struct eerbuffer * eerb,char * data,int count)149 static int dasd_eer_read_buffer(struct eerbuffer *eerb, char *data, int count)
150 {
151
152 unsigned long tailindex,localtail;
153 unsigned long rest, len, finalcount;
154 char *nextdata;
155
156 finalcount = min(count, dasd_eer_get_filled_bytes(eerb));
157 nextdata = data;
158 rest = finalcount;
159 while (rest > 0) {
160 tailindex = eerb->tail / PAGE_SIZE;
161 localtail = eerb->tail % PAGE_SIZE;
162 len = min(rest, PAGE_SIZE - localtail);
163 memcpy(nextdata, eerb->buffer[tailindex] + localtail, len);
164 nextdata += len;
165 rest -= len;
166 eerb->tail += len;
167 if (eerb->tail == eerb->buffersize)
168 eerb->tail = 0; /* wrap around */
169 BUG_ON(eerb->tail > eerb->buffersize);
170 }
171 return finalcount;
172 }
173
174 /*
175 * Whenever you want to write a blob of data to the internal buffer you
176 * have to start by using this function first. It will write the number
177 * of bytes that will be written to the buffer. If necessary it will remove
178 * old records to make room for the new one.
179 * Needs to be called with bufferlock held.
180 */
dasd_eer_start_record(struct eerbuffer * eerb,int count)181 static int dasd_eer_start_record(struct eerbuffer *eerb, int count)
182 {
183 int tailcount;
184
185 if (count + sizeof(count) > eerb->buffersize)
186 return -ENOMEM;
187 while (dasd_eer_get_free_bytes(eerb) < count + sizeof(count)) {
188 if (eerb->residual > 0) {
189 eerb->tail += eerb->residual;
190 if (eerb->tail >= eerb->buffersize)
191 eerb->tail -= eerb->buffersize;
192 eerb->residual = -1;
193 }
194 dasd_eer_read_buffer(eerb, (char *) &tailcount,
195 sizeof(tailcount));
196 eerb->tail += tailcount;
197 if (eerb->tail >= eerb->buffersize)
198 eerb->tail -= eerb->buffersize;
199 }
200 dasd_eer_write_buffer(eerb, (char*) &count, sizeof(count));
201
202 return 0;
203 };
204
205 /*
206 * Release pages that are not used anymore.
207 */
dasd_eer_free_buffer_pages(char ** buf,int no_pages)208 static void dasd_eer_free_buffer_pages(char **buf, int no_pages)
209 {
210 int i;
211
212 for (i = 0; i < no_pages; i++)
213 free_page((unsigned long) buf[i]);
214 }
215
216 /*
217 * Allocate a new set of memory pages.
218 */
dasd_eer_allocate_buffer_pages(char ** buf,int no_pages)219 static int dasd_eer_allocate_buffer_pages(char **buf, int no_pages)
220 {
221 int i;
222
223 for (i = 0; i < no_pages; i++) {
224 buf[i] = (char *) get_zeroed_page(GFP_KERNEL);
225 if (!buf[i]) {
226 dasd_eer_free_buffer_pages(buf, i);
227 return -ENOMEM;
228 }
229 }
230 return 0;
231 }
232
233 /*
234 * SECTION: The extended error reporting functionality
235 */
236
237 /*
238 * When a DASD device driver wants to report an error, it calls the
239 * function dasd_eer_write and gives the respective trigger ID as
240 * parameter. Currently there are four kinds of triggers:
241 *
242 * DASD_EER_FATALERROR: all kinds of unrecoverable I/O problems
243 * DASD_EER_PPRCSUSPEND: PPRC was suspended
244 * DASD_EER_NOPATH: There is no path to the device left.
245 * DASD_EER_STATECHANGE: The state of the device has changed.
246 *
247 * For the first three triggers all required information can be supplied by
248 * the caller. For these triggers a record is written by the function
249 * dasd_eer_write_standard_trigger.
250 *
251 * The DASD_EER_STATECHANGE trigger is special since a sense subsystem
252 * status ccw need to be executed to gather the necessary sense data first.
253 * The dasd_eer_snss function will queue the SNSS request and the request
254 * callback will then call dasd_eer_write with the DASD_EER_STATCHANGE
255 * trigger.
256 *
257 * To avoid memory allocations at runtime, the necessary memory is allocated
258 * when the extended error reporting is enabled for a device (by
259 * dasd_eer_probe). There is one sense subsystem status request for each
260 * eer enabled DASD device. The presence of the cqr in device->eer_cqr
261 * indicates that eer is enable for the device. The use of the snss request
262 * is protected by the DASD_FLAG_EER_IN_USE bit. When this flag indicates
263 * that the cqr is currently in use, dasd_eer_snss cannot start a second
264 * request but sets the DASD_FLAG_EER_SNSS flag instead. The callback of
265 * the SNSS request will check the bit and call dasd_eer_snss again.
266 */
267
268 #define SNSS_DATA_SIZE 44
269
270 #define DASD_EER_BUSID_SIZE 10
271 struct dasd_eer_header {
272 __u32 total_size;
273 __u32 trigger;
274 __u64 tv_sec;
275 __u64 tv_usec;
276 char busid[DASD_EER_BUSID_SIZE];
277 } __attribute__ ((packed));
278
279 /*
280 * The following function can be used for those triggers that have
281 * all necessary data available when the function is called.
282 * If the parameter cqr is not NULL, the chain of requests will be searched
283 * for valid sense data, and all valid sense data sets will be added to
284 * the triggers data.
285 */
dasd_eer_write_standard_trigger(struct dasd_device * device,struct dasd_ccw_req * cqr,int trigger)286 static void dasd_eer_write_standard_trigger(struct dasd_device *device,
287 struct dasd_ccw_req *cqr,
288 int trigger)
289 {
290 struct dasd_ccw_req *temp_cqr;
291 int data_size;
292 struct timespec64 ts;
293 struct dasd_eer_header header;
294 unsigned long flags;
295 struct eerbuffer *eerb;
296 char *sense;
297
298 /* go through cqr chain and count the valid sense data sets */
299 data_size = 0;
300 for (temp_cqr = cqr; temp_cqr; temp_cqr = temp_cqr->refers)
301 if (dasd_get_sense(&temp_cqr->irb))
302 data_size += 32;
303
304 header.total_size = sizeof(header) + data_size + 4; /* "EOR" */
305 header.trigger = trigger;
306 ktime_get_real_ts64(&ts);
307 header.tv_sec = ts.tv_sec;
308 header.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
309 strscpy(header.busid, dev_name(&device->cdev->dev),
310 DASD_EER_BUSID_SIZE);
311
312 spin_lock_irqsave(&bufferlock, flags);
313 list_for_each_entry(eerb, &bufferlist, list) {
314 dasd_eer_start_record(eerb, header.total_size);
315 dasd_eer_write_buffer(eerb, (char *) &header, sizeof(header));
316 for (temp_cqr = cqr; temp_cqr; temp_cqr = temp_cqr->refers) {
317 sense = dasd_get_sense(&temp_cqr->irb);
318 if (sense)
319 dasd_eer_write_buffer(eerb, sense, 32);
320 }
321 dasd_eer_write_buffer(eerb, "EOR", 4);
322 }
323 spin_unlock_irqrestore(&bufferlock, flags);
324 wake_up_interruptible(&dasd_eer_read_wait_queue);
325 }
326
327 /*
328 * This function writes a DASD_EER_STATECHANGE trigger.
329 */
dasd_eer_write_snss_trigger(struct dasd_device * device,struct dasd_ccw_req * cqr,int trigger)330 static void dasd_eer_write_snss_trigger(struct dasd_device *device,
331 struct dasd_ccw_req *cqr,
332 int trigger)
333 {
334 int data_size;
335 int snss_rc;
336 struct timespec64 ts;
337 struct dasd_eer_header header;
338 unsigned long flags;
339 struct eerbuffer *eerb;
340
341 snss_rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
342 if (snss_rc)
343 data_size = 0;
344 else
345 data_size = SNSS_DATA_SIZE;
346
347 header.total_size = sizeof(header) + data_size + 4; /* "EOR" */
348 header.trigger = DASD_EER_STATECHANGE;
349 ktime_get_real_ts64(&ts);
350 header.tv_sec = ts.tv_sec;
351 header.tv_usec = ts.tv_nsec / NSEC_PER_USEC;
352 strscpy(header.busid, dev_name(&device->cdev->dev),
353 DASD_EER_BUSID_SIZE);
354
355 spin_lock_irqsave(&bufferlock, flags);
356 list_for_each_entry(eerb, &bufferlist, list) {
357 dasd_eer_start_record(eerb, header.total_size);
358 dasd_eer_write_buffer(eerb, (char *) &header , sizeof(header));
359 if (!snss_rc)
360 dasd_eer_write_buffer(eerb, cqr->data, SNSS_DATA_SIZE);
361 dasd_eer_write_buffer(eerb, "EOR", 4);
362 }
363 spin_unlock_irqrestore(&bufferlock, flags);
364 wake_up_interruptible(&dasd_eer_read_wait_queue);
365 }
366
367 /*
368 * This function is called for all triggers. It calls the appropriate
369 * function that writes the actual trigger records.
370 */
dasd_eer_write(struct dasd_device * device,struct dasd_ccw_req * cqr,unsigned int id)371 void dasd_eer_write(struct dasd_device *device, struct dasd_ccw_req *cqr,
372 unsigned int id)
373 {
374 if (!device->eer_cqr)
375 return;
376 switch (id) {
377 case DASD_EER_FATALERROR:
378 case DASD_EER_PPRCSUSPEND:
379 dasd_eer_write_standard_trigger(device, cqr, id);
380 break;
381 case DASD_EER_NOPATH:
382 case DASD_EER_NOSPC:
383 case DASD_EER_AUTOQUIESCE:
384 dasd_eer_write_standard_trigger(device, NULL, id);
385 break;
386 case DASD_EER_STATECHANGE:
387 dasd_eer_write_snss_trigger(device, cqr, id);
388 break;
389 default: /* unknown trigger, so we write it without any sense data */
390 dasd_eer_write_standard_trigger(device, NULL, id);
391 break;
392 }
393 }
394 EXPORT_SYMBOL(dasd_eer_write);
395
396 /*
397 * Start a sense subsystem status request.
398 * Needs to be called with the device held.
399 */
dasd_eer_snss(struct dasd_device * device)400 void dasd_eer_snss(struct dasd_device *device)
401 {
402 struct dasd_ccw_req *cqr;
403
404 cqr = device->eer_cqr;
405 if (!cqr) /* Device not eer enabled. */
406 return;
407 if (test_and_set_bit(DASD_FLAG_EER_IN_USE, &device->flags)) {
408 /* Sense subsystem status request in use. */
409 set_bit(DASD_FLAG_EER_SNSS, &device->flags);
410 return;
411 }
412 /* cdev is already locked, can't use dasd_add_request_head */
413 clear_bit(DASD_FLAG_EER_SNSS, &device->flags);
414 cqr->status = DASD_CQR_QUEUED;
415 list_add(&cqr->devlist, &device->ccw_queue);
416 dasd_schedule_device_bh(device);
417 }
418
419 /*
420 * Callback function for use with sense subsystem status request.
421 */
dasd_eer_snss_cb(struct dasd_ccw_req * cqr,void * data)422 static void dasd_eer_snss_cb(struct dasd_ccw_req *cqr, void *data)
423 {
424 struct dasd_device *device = cqr->startdev;
425 unsigned long flags;
426
427 dasd_eer_write(device, cqr, DASD_EER_STATECHANGE);
428 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
429 if (device->eer_cqr == cqr) {
430 clear_bit(DASD_FLAG_EER_IN_USE, &device->flags);
431 if (test_bit(DASD_FLAG_EER_SNSS, &device->flags))
432 /* Another SNSS has been requested in the meantime. */
433 dasd_eer_snss(device);
434 cqr = NULL;
435 }
436 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
437 if (cqr)
438 /*
439 * Extended error recovery has been switched off while
440 * the SNSS request was running. It could even have
441 * been switched off and on again in which case there
442 * is a new ccw in device->eer_cqr. Free the "old"
443 * snss request now.
444 */
445 dasd_sfree_request(cqr, device);
446 }
447
448 /*
449 * Enable error reporting on a given device.
450 */
dasd_eer_enable(struct dasd_device * device)451 int dasd_eer_enable(struct dasd_device *device)
452 {
453 struct dasd_ccw_req *cqr = NULL;
454 unsigned long flags;
455 struct ccw1 *ccw;
456 int rc = 0;
457
458 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
459 if (device->eer_cqr)
460 goto out;
461 else if (!device->discipline ||
462 strcmp(device->discipline->name, "ECKD"))
463 rc = -EMEDIUMTYPE;
464 else if (test_bit(DASD_FLAG_OFFLINE, &device->flags))
465 rc = -EBUSY;
466
467 if (rc)
468 goto out;
469
470 cqr = dasd_smalloc_request(DASD_ECKD_MAGIC, 1 /* SNSS */,
471 SNSS_DATA_SIZE, device, NULL);
472 if (IS_ERR(cqr)) {
473 rc = -ENOMEM;
474 cqr = NULL;
475 goto out;
476 }
477
478 cqr->startdev = device;
479 cqr->retries = 255;
480 cqr->expires = 10 * HZ;
481 clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
482 set_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags);
483
484 ccw = cqr->cpaddr;
485 ccw->cmd_code = DASD_ECKD_CCW_SNSS;
486 ccw->count = SNSS_DATA_SIZE;
487 ccw->flags = 0;
488 ccw->cda = virt_to_dma32(cqr->data);
489
490 cqr->buildclk = get_tod_clock();
491 cqr->status = DASD_CQR_FILLED;
492 cqr->callback = dasd_eer_snss_cb;
493
494 if (!device->eer_cqr) {
495 device->eer_cqr = cqr;
496 cqr = NULL;
497 }
498
499 out:
500 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
501
502 if (cqr)
503 dasd_sfree_request(cqr, device);
504
505 return rc;
506 }
507
508 /*
509 * Disable error reporting on a given device.
510 */
dasd_eer_disable(struct dasd_device * device)511 void dasd_eer_disable(struct dasd_device *device)
512 {
513 struct dasd_ccw_req *cqr;
514 unsigned long flags;
515 int in_use;
516
517 if (!device->eer_cqr)
518 return;
519 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
520 cqr = device->eer_cqr;
521 device->eer_cqr = NULL;
522 clear_bit(DASD_FLAG_EER_SNSS, &device->flags);
523 in_use = test_and_clear_bit(DASD_FLAG_EER_IN_USE, &device->flags);
524 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
525 if (cqr && !in_use)
526 dasd_sfree_request(cqr, device);
527 }
528
529 /*
530 * SECTION: the device operations
531 */
532
533 /*
534 * On the one side we need a lock to access our internal buffer, on the
535 * other side a copy_to_user can sleep. So we need to copy the data we have
536 * to transfer in a readbuffer, which is protected by the readbuffer_mutex.
537 */
538 static char readbuffer[PAGE_SIZE];
539 static DEFINE_MUTEX(readbuffer_mutex);
540
dasd_eer_open(struct inode * inp,struct file * filp)541 static int dasd_eer_open(struct inode *inp, struct file *filp)
542 {
543 struct eerbuffer *eerb;
544 unsigned long flags;
545
546 eerb = kzalloc(sizeof(struct eerbuffer), GFP_KERNEL);
547 if (!eerb)
548 return -ENOMEM;
549 eerb->buffer_page_count = eer_pages;
550 if (eerb->buffer_page_count < 1 ||
551 eerb->buffer_page_count > INT_MAX / PAGE_SIZE) {
552 kfree(eerb);
553 DBF_EVENT(DBF_WARNING, "can't open device since module "
554 "parameter eer_pages is smaller than 1 or"
555 " bigger than %d", (int)(INT_MAX / PAGE_SIZE));
556 return -EINVAL;
557 }
558 eerb->buffersize = eerb->buffer_page_count * PAGE_SIZE;
559 eerb->buffer = kmalloc_array(eerb->buffer_page_count, sizeof(char *),
560 GFP_KERNEL);
561 if (!eerb->buffer) {
562 kfree(eerb);
563 return -ENOMEM;
564 }
565 if (dasd_eer_allocate_buffer_pages(eerb->buffer,
566 eerb->buffer_page_count)) {
567 kfree(eerb->buffer);
568 kfree(eerb);
569 return -ENOMEM;
570 }
571 filp->private_data = eerb;
572 spin_lock_irqsave(&bufferlock, flags);
573 list_add(&eerb->list, &bufferlist);
574 spin_unlock_irqrestore(&bufferlock, flags);
575
576 return nonseekable_open(inp,filp);
577 }
578
dasd_eer_close(struct inode * inp,struct file * filp)579 static int dasd_eer_close(struct inode *inp, struct file *filp)
580 {
581 struct eerbuffer *eerb;
582 unsigned long flags;
583
584 eerb = (struct eerbuffer *) filp->private_data;
585 spin_lock_irqsave(&bufferlock, flags);
586 list_del(&eerb->list);
587 spin_unlock_irqrestore(&bufferlock, flags);
588 dasd_eer_free_buffer_pages(eerb->buffer, eerb->buffer_page_count);
589 kfree(eerb->buffer);
590 kfree(eerb);
591
592 return 0;
593 }
594
dasd_eer_read(struct file * filp,char __user * buf,size_t count,loff_t * ppos)595 static ssize_t dasd_eer_read(struct file *filp, char __user *buf,
596 size_t count, loff_t *ppos)
597 {
598 int tc,rc;
599 int tailcount,effective_count;
600 unsigned long flags;
601 struct eerbuffer *eerb;
602
603 eerb = (struct eerbuffer *) filp->private_data;
604 if (mutex_lock_interruptible(&readbuffer_mutex))
605 return -ERESTARTSYS;
606
607 spin_lock_irqsave(&bufferlock, flags);
608
609 if (eerb->residual < 0) { /* the remainder of this record */
610 /* has been deleted */
611 eerb->residual = 0;
612 spin_unlock_irqrestore(&bufferlock, flags);
613 mutex_unlock(&readbuffer_mutex);
614 return -EIO;
615 } else if (eerb->residual > 0) {
616 /* OK we still have a second half of a record to deliver */
617 effective_count = min(eerb->residual, (int) count);
618 eerb->residual -= effective_count;
619 } else {
620 tc = 0;
621 while (!tc) {
622 tc = dasd_eer_read_buffer(eerb, (char *) &tailcount,
623 sizeof(tailcount));
624 if (!tc) {
625 /* no data available */
626 spin_unlock_irqrestore(&bufferlock, flags);
627 mutex_unlock(&readbuffer_mutex);
628 if (filp->f_flags & O_NONBLOCK)
629 return -EAGAIN;
630 rc = wait_event_interruptible(
631 dasd_eer_read_wait_queue,
632 eerb->head != eerb->tail);
633 if (rc)
634 return rc;
635 if (mutex_lock_interruptible(&readbuffer_mutex))
636 return -ERESTARTSYS;
637 spin_lock_irqsave(&bufferlock, flags);
638 }
639 }
640 WARN_ON(tc != sizeof(tailcount));
641 effective_count = min(tailcount,(int)count);
642 eerb->residual = tailcount - effective_count;
643 }
644
645 tc = dasd_eer_read_buffer(eerb, readbuffer, effective_count);
646 WARN_ON(tc != effective_count);
647
648 spin_unlock_irqrestore(&bufferlock, flags);
649
650 if (copy_to_user(buf, readbuffer, effective_count)) {
651 mutex_unlock(&readbuffer_mutex);
652 return -EFAULT;
653 }
654
655 mutex_unlock(&readbuffer_mutex);
656 return effective_count;
657 }
658
dasd_eer_poll(struct file * filp,poll_table * ptable)659 static __poll_t dasd_eer_poll(struct file *filp, poll_table *ptable)
660 {
661 __poll_t mask;
662 unsigned long flags;
663 struct eerbuffer *eerb;
664
665 eerb = (struct eerbuffer *) filp->private_data;
666 poll_wait(filp, &dasd_eer_read_wait_queue, ptable);
667 spin_lock_irqsave(&bufferlock, flags);
668 if (eerb->head != eerb->tail)
669 mask = EPOLLIN | EPOLLRDNORM ;
670 else
671 mask = 0;
672 spin_unlock_irqrestore(&bufferlock, flags);
673 return mask;
674 }
675
676 static const struct file_operations dasd_eer_fops = {
677 .open = &dasd_eer_open,
678 .release = &dasd_eer_close,
679 .read = &dasd_eer_read,
680 .poll = &dasd_eer_poll,
681 .owner = THIS_MODULE,
682 .llseek = noop_llseek,
683 };
684
685 static struct miscdevice *dasd_eer_dev = NULL;
686
dasd_eer_init(void)687 int __init dasd_eer_init(void)
688 {
689 int rc;
690
691 dasd_eer_dev = kzalloc(sizeof(*dasd_eer_dev), GFP_KERNEL);
692 if (!dasd_eer_dev)
693 return -ENOMEM;
694
695 dasd_eer_dev->minor = MISC_DYNAMIC_MINOR;
696 dasd_eer_dev->name = "dasd_eer";
697 dasd_eer_dev->fops = &dasd_eer_fops;
698
699 rc = misc_register(dasd_eer_dev);
700 if (rc) {
701 kfree(dasd_eer_dev);
702 dasd_eer_dev = NULL;
703 DBF_EVENT(DBF_ERR, "%s", "dasd_eer_init could not "
704 "register misc device");
705 return rc;
706 }
707
708 return 0;
709 }
710
dasd_eer_exit(void)711 void dasd_eer_exit(void)
712 {
713 if (dasd_eer_dev) {
714 misc_deregister(dasd_eer_dev);
715 kfree(dasd_eer_dev);
716 dasd_eer_dev = NULL;
717 }
718 }
719