1 // SPDX-License-Identifier: GPL-2.0
3 * Character device driver for extended error reporting.
5 * Copyright IBM Corp. 2005
6 * extended error reporting for DASD ECKD devices
7 * Author(s): Stefan Weinhuber <wein@de.ibm.com>
10 #include <linux/init.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>
22 #include <linux/uaccess.h>
23 #include <linux/atomic.h>
24 #include <asm/ebcdic.h>
27 #include "dasd_eckd.h"
30 * SECTION: the internal buffer
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.
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.
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.
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.
57 * - dasd_eer_read_buffer
59 * For all mentioned functions you need to get the bufferlock first and keep
60 * it until a complete record is written or read.
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.
76 static int eer_pages = 5;
77 module_param(eer_pages, int, S_IRUGO|S_IWUSR);
80 struct list_head list;
83 int buffer_page_count;
89 static LIST_HEAD(bufferlist);
90 static DEFINE_SPINLOCK(bufferlock);
91 static DECLARE_WAIT_QUEUE_HEAD(dasd_eer_read_wait_queue);
94 * How many free bytes are available on the buffer.
95 * Needs to be called with bufferlock held.
97 static int dasd_eer_get_free_bytes(struct eerbuffer *eerb)
99 if (eerb->head < eerb->tail)
100 return eerb->tail - eerb->head - 1;
101 return eerb->buffersize - eerb->head + eerb->tail -1;
105 * How many bytes of buffer space are used.
106 * Needs to be called with bufferlock held.
108 static int dasd_eer_get_filled_bytes(struct eerbuffer *eerb)
111 if (eerb->head >= eerb->tail)
112 return eerb->head - eerb->tail;
113 return eerb->buffersize - eerb->tail + eerb->head;
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.
122 static void dasd_eer_write_buffer(struct eerbuffer *eerb,
123 char *data, int count)
126 unsigned long headindex,localhead;
127 unsigned long rest, len;
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);
140 if (eerb->head == eerb->buffersize)
141 eerb->head = 0; /* wrap around */
142 BUG_ON(eerb->head > eerb->buffersize);
147 * Needs to be called with bufferlock held.
149 static int dasd_eer_read_buffer(struct eerbuffer *eerb, char *data, int count)
152 unsigned long tailindex,localtail;
153 unsigned long rest, len, finalcount;
156 finalcount = min(count, dasd_eer_get_filled_bytes(eerb));
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);
167 if (eerb->tail == eerb->buffersize)
168 eerb->tail = 0; /* wrap around */
169 BUG_ON(eerb->tail > eerb->buffersize);
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.
181 static int dasd_eer_start_record(struct eerbuffer *eerb, int count)
185 if (count + sizeof(count) > eerb->buffersize)
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;
194 dasd_eer_read_buffer(eerb, (char *) &tailcount,
196 eerb->tail += tailcount;
197 if (eerb->tail >= eerb->buffersize)
198 eerb->tail -= eerb->buffersize;
200 dasd_eer_write_buffer(eerb, (char*) &count, sizeof(count));
206 * Release pages that are not used anymore.
208 static void dasd_eer_free_buffer_pages(char **buf, int no_pages)
212 for (i = 0; i < no_pages; i++)
213 free_page((unsigned long) buf[i]);
217 * Allocate a new set of memory pages.
219 static int dasd_eer_allocate_buffer_pages(char **buf, int no_pages)
223 for (i = 0; i < no_pages; i++) {
224 buf[i] = (char *) get_zeroed_page(GFP_KERNEL);
226 dasd_eer_free_buffer_pages(buf, i);
234 * SECTION: The extended error reporting functionality
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:
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.
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.
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
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.
268 #define SNSS_DATA_SIZE 44
270 #define DASD_EER_BUSID_SIZE 10
271 struct dasd_eer_header {
276 char busid[DASD_EER_BUSID_SIZE];
277 } __attribute__ ((packed));
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
286 static void dasd_eer_write_standard_trigger(struct dasd_device *device,
287 struct dasd_ccw_req *cqr,
290 struct dasd_ccw_req *temp_cqr;
292 struct timespec64 ts;
293 struct dasd_eer_header header;
295 struct eerbuffer *eerb;
298 /* go through cqr chain and count the valid sense data sets */
300 for (temp_cqr = cqr; temp_cqr; temp_cqr = temp_cqr->refers)
301 if (dasd_get_sense(&temp_cqr->irb))
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);
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);
319 dasd_eer_write_buffer(eerb, sense, 32);
321 dasd_eer_write_buffer(eerb, "EOR", 4);
323 spin_unlock_irqrestore(&bufferlock, flags);
324 wake_up_interruptible(&dasd_eer_read_wait_queue);
328 * This function writes a DASD_EER_STATECHANGE trigger.
330 static void dasd_eer_write_snss_trigger(struct dasd_device *device,
331 struct dasd_ccw_req *cqr,
336 struct timespec64 ts;
337 struct dasd_eer_header header;
339 struct eerbuffer *eerb;
341 snss_rc = (cqr->status == DASD_CQR_DONE) ? 0 : -EIO;
345 data_size = SNSS_DATA_SIZE;
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);
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));
360 dasd_eer_write_buffer(eerb, cqr->data, SNSS_DATA_SIZE);
361 dasd_eer_write_buffer(eerb, "EOR", 4);
363 spin_unlock_irqrestore(&bufferlock, flags);
364 wake_up_interruptible(&dasd_eer_read_wait_queue);
368 * This function is called for all triggers. It calls the appropriate
369 * function that writes the actual trigger records.
371 void dasd_eer_write(struct dasd_device *device, struct dasd_ccw_req *cqr,
374 if (!device->eer_cqr)
377 case DASD_EER_FATALERROR:
378 case DASD_EER_PPRCSUSPEND:
379 dasd_eer_write_standard_trigger(device, cqr, id);
381 case DASD_EER_NOPATH:
383 case DASD_EER_AUTOQUIESCE:
384 dasd_eer_write_standard_trigger(device, NULL, id);
386 case DASD_EER_STATECHANGE:
387 dasd_eer_write_snss_trigger(device, cqr, id);
389 default: /* unknown trigger, so we write it without any sense data */
390 dasd_eer_write_standard_trigger(device, NULL, id);
394 EXPORT_SYMBOL(dasd_eer_write);
397 * Start a sense subsystem status request.
398 * Needs to be called with the device held.
400 void dasd_eer_snss(struct dasd_device *device)
402 struct dasd_ccw_req *cqr;
404 cqr = device->eer_cqr;
405 if (!cqr) /* Device not eer enabled. */
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);
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);
420 * Callback function for use with sense subsystem status request.
422 static void dasd_eer_snss_cb(struct dasd_ccw_req *cqr, void *data)
424 struct dasd_device *device = cqr->startdev;
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);
436 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
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"
445 dasd_sfree_request(cqr, device);
449 * Enable error reporting on a given device.
451 int dasd_eer_enable(struct dasd_device *device)
453 struct dasd_ccw_req *cqr = NULL;
458 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
461 else if (!device->discipline ||
462 strcmp(device->discipline->name, "ECKD"))
464 else if (test_bit(DASD_FLAG_OFFLINE, &device->flags))
470 cqr = dasd_smalloc_request(DASD_ECKD_MAGIC, 1 /* SNSS */,
471 SNSS_DATA_SIZE, device, NULL);
478 cqr->startdev = device;
480 cqr->expires = 10 * HZ;
481 clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
482 set_bit(DASD_CQR_ALLOW_SLOCK, &cqr->flags);
485 ccw->cmd_code = DASD_ECKD_CCW_SNSS;
486 ccw->count = SNSS_DATA_SIZE;
488 ccw->cda = (__u32)virt_to_phys(cqr->data);
490 cqr->buildclk = get_tod_clock();
491 cqr->status = DASD_CQR_FILLED;
492 cqr->callback = dasd_eer_snss_cb;
494 if (!device->eer_cqr) {
495 device->eer_cqr = cqr;
500 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
503 dasd_sfree_request(cqr, device);
509 * Disable error reporting on a given device.
511 void dasd_eer_disable(struct dasd_device *device)
513 struct dasd_ccw_req *cqr;
517 if (!device->eer_cqr)
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);
526 dasd_sfree_request(cqr, device);
530 * SECTION: the device operations
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.
538 static char readbuffer[PAGE_SIZE];
539 static DEFINE_MUTEX(readbuffer_mutex);
541 static int dasd_eer_open(struct inode *inp, struct file *filp)
543 struct eerbuffer *eerb;
546 eerb = kzalloc(sizeof(struct eerbuffer), GFP_KERNEL);
549 eerb->buffer_page_count = eer_pages;
550 if (eerb->buffer_page_count < 1 ||
551 eerb->buffer_page_count > INT_MAX / PAGE_SIZE) {
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));
558 eerb->buffersize = eerb->buffer_page_count * PAGE_SIZE;
559 eerb->buffer = kmalloc_array(eerb->buffer_page_count, sizeof(char *),
565 if (dasd_eer_allocate_buffer_pages(eerb->buffer,
566 eerb->buffer_page_count)) {
571 filp->private_data = eerb;
572 spin_lock_irqsave(&bufferlock, flags);
573 list_add(&eerb->list, &bufferlist);
574 spin_unlock_irqrestore(&bufferlock, flags);
576 return nonseekable_open(inp,filp);
579 static int dasd_eer_close(struct inode *inp, struct file *filp)
581 struct eerbuffer *eerb;
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);
595 static ssize_t dasd_eer_read(struct file *filp, char __user *buf,
596 size_t count, loff_t *ppos)
599 int tailcount,effective_count;
601 struct eerbuffer *eerb;
603 eerb = (struct eerbuffer *) filp->private_data;
604 if (mutex_lock_interruptible(&readbuffer_mutex))
607 spin_lock_irqsave(&bufferlock, flags);
609 if (eerb->residual < 0) { /* the remainder of this record */
610 /* has been deleted */
612 spin_unlock_irqrestore(&bufferlock, flags);
613 mutex_unlock(&readbuffer_mutex);
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;
622 tc = dasd_eer_read_buffer(eerb, (char *) &tailcount,
625 /* no data available */
626 spin_unlock_irqrestore(&bufferlock, flags);
627 mutex_unlock(&readbuffer_mutex);
628 if (filp->f_flags & O_NONBLOCK)
630 rc = wait_event_interruptible(
631 dasd_eer_read_wait_queue,
632 eerb->head != eerb->tail);
635 if (mutex_lock_interruptible(&readbuffer_mutex))
637 spin_lock_irqsave(&bufferlock, flags);
640 WARN_ON(tc != sizeof(tailcount));
641 effective_count = min(tailcount,(int)count);
642 eerb->residual = tailcount - effective_count;
645 tc = dasd_eer_read_buffer(eerb, readbuffer, effective_count);
646 WARN_ON(tc != effective_count);
648 spin_unlock_irqrestore(&bufferlock, flags);
650 if (copy_to_user(buf, readbuffer, effective_count)) {
651 mutex_unlock(&readbuffer_mutex);
655 mutex_unlock(&readbuffer_mutex);
656 return effective_count;
659 static __poll_t dasd_eer_poll(struct file *filp, poll_table *ptable)
663 struct eerbuffer *eerb;
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 ;
672 spin_unlock_irqrestore(&bufferlock, flags);
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,
685 static struct miscdevice *dasd_eer_dev = NULL;
687 int __init dasd_eer_init(void)
691 dasd_eer_dev = kzalloc(sizeof(*dasd_eer_dev), GFP_KERNEL);
695 dasd_eer_dev->minor = MISC_DYNAMIC_MINOR;
696 dasd_eer_dev->name = "dasd_eer";
697 dasd_eer_dev->fops = &dasd_eer_fops;
699 rc = misc_register(dasd_eer_dev);
703 DBF_EVENT(DBF_ERR, "%s", "dasd_eer_init could not "
704 "register misc device");
711 void dasd_eer_exit(void)
714 misc_deregister(dasd_eer_dev);