diff options
Diffstat (limited to 'drivers/s390/block/dasd_eer.c')
| -rw-r--r-- | drivers/s390/block/dasd_eer.c | 682 |
1 files changed, 682 insertions, 0 deletions
diff --git a/drivers/s390/block/dasd_eer.c b/drivers/s390/block/dasd_eer.c new file mode 100644 index 000000000000..2d946b6ca074 --- /dev/null +++ b/drivers/s390/block/dasd_eer.c @@ -0,0 +1,682 @@ +/* + * Character device driver for extended error reporting. + * + * Copyright (C) 2005 IBM Corporation + * extended error reporting for DASD ECKD devices + * Author(s): Stefan Weinhuber <wein@de.ibm.com> + */ + +#include <linux/init.h> +#include <linux/fs.h> +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/device.h> +#include <linux/poll.h> + +#include <asm/uaccess.h> +#include <asm/semaphore.h> +#include <asm/atomic.h> +#include <asm/ebcdic.h> + +#include "dasd_int.h" +#include "dasd_eckd.h" + +#ifdef PRINTK_HEADER +#undef PRINTK_HEADER +#endif /* PRINTK_HEADER */ +#define PRINTK_HEADER "dasd(eer):" + +/* + * SECTION: the internal buffer + */ + +/* + * The internal buffer is meant to store obaque blobs of data, so it does + * not know of higher level concepts like triggers. + * It consists of a number of pages that are used as a ringbuffer. Each data + * blob is stored in a simple record that consists of an integer, which + * contains the size of the following data, and the data bytes themselfes. + * + * To allow for multiple independent readers we create one internal buffer + * each time the device is opened and destroy the buffer when the file is + * closed again. The number of pages used for this buffer is determined by + * the module parmeter eer_pages. + * + * One record can be written to a buffer by using the functions + * - dasd_eer_start_record (one time per record to write the size to the + * buffer and reserve the space for the data) + * - dasd_eer_write_buffer (one or more times per record to write the data) + * The data can be written in several steps but you will have to compute + * the total size up front for the invocation of dasd_eer_start_record. + * If the ringbuffer is full, dasd_eer_start_record will remove the required + * number of old records. + * + * A record is typically read in two steps, first read the integer that + * specifies the size of the following data, then read the data. + * Both can be done by + * - dasd_eer_read_buffer + * + * For all mentioned functions you need to get the bufferlock first and keep + * it until a complete record is written or read. + * + * All information necessary to keep track of an internal buffer is kept in + * a struct eerbuffer. The buffer specific to a file pointer is strored in + * the private_data field of that file. To be able to write data to all + * existing buffers, each buffer is also added to the bufferlist. + * If the user does not want to read a complete record in one go, we have to + * keep track of the rest of the record. residual stores the number of bytes + * that are still to deliver. If the rest of the record is invalidated between + * two reads then residual will be set to -1 so that the next read will fail. + * All entries in the eerbuffer structure are protected with the bufferlock. + * To avoid races between writing to a buffer on the one side and creating + * and destroying buffers on the other side, the bufferlock must also be used + * to protect the bufferlist. + */ + +static int eer_pages = 5; +module_param(eer_pages, int, S_IRUGO|S_IWUSR); + +struct eerbuffer { + struct list_head list; + char **buffer; + int buffersize; + int buffer_page_count; + int head; + int tail; + int residual; +}; + +static LIST_HEAD(bufferlist); +static spinlock_t bufferlock = SPIN_LOCK_UNLOCKED; +static DECLARE_WAIT_QUEUE_HEAD(dasd_eer_read_wait_queue); + +/* + * How many free bytes are available on the buffer. + * Needs to be called with bufferlock held. + */ +static int dasd_eer_get_free_bytes(struct eerbuffer *eerb) +{ + if (eerb->head < eerb->tail) + return eerb->tail - eerb->head - 1; + return eerb->buffersize - eerb->head + eerb->tail -1; +} + +/* + * How many bytes of buffer space are used. + * Needs to be called with bufferlock held. + */ +static int dasd_eer_get_filled_bytes(struct eerbuffer *eerb) +{ + + if (eerb->head >= eerb->tail) + return eerb->head - eerb->tail; + return eerb->buffersize - eerb->tail + eerb->head; +} + +/* + * The dasd_eer_write_buffer function just copies count bytes of data + * to the buffer. Make sure to call dasd_eer_start_record first, to + * make sure that enough free space is available. + * Needs to be called with bufferlock held. + */ +static void dasd_eer_write_buffer(struct eerbuffer *eerb, + char *data, int count) +{ + + unsigned long headindex,localhead; + unsigned long rest, len; + char *nextdata; + + nextdata = data; + rest = count; + while (rest > 0) { + headindex = eerb->head / PAGE_SIZE; + localhead = eerb->head % PAGE_SIZE; + len = min(rest, PAGE_SIZE - localhead); + memcpy(eerb->buffer[headindex]+localhead, nextdata, len); + nextdata += len; + rest -= len; + eerb->head += len; + if (eerb->head == eerb->buffersize) + eerb->head = 0; /* wrap around */ + BUG_ON(eerb->head > eerb->buffersize); + } +} + +/* + * Needs to be called with bufferlock held. + */ +static int dasd_eer_read_buffer(struct eerbuffer *eerb, char *data, int count) +{ + + unsigned long tailindex,localtail; + unsigned long rest, len, finalcount; + char *nextdata; + + finalcount = min(count, dasd_eer_get_filled_bytes(eerb)); + nextdata = data; + rest = finalcount; + while (rest > 0) { + tailindex = eerb->tail / PAGE_SIZE; + localtail = eerb->tail % PAGE_SIZE; + len = min(rest, PAGE_SIZE - localtail); + memcpy(nextdata, eerb->buffer[tailindex] + localtail, len); + nextdata += len; + rest -= len; + eerb->tail += len; + if (eerb->tail == eerb->buffersize) + eerb->tail = 0; /* wrap around */ + BUG_ON(eerb->tail > eerb->buffersize); + } + return finalcount; +} + +/* + * Whenever you want to write a blob of data to the internal buffer you + * have to start by using this function first. It will write the number + * of bytes that will be written to the buffer. If necessary it will remove + * old records to make room for the new one. + * Needs to be called with bufferlock held. + */ +static int dasd_eer_start_record(struct eerbuffer *eerb, int count) +{ + int tailcount; + + if (count + sizeof(count) > eerb->buffersize) + return -ENOMEM; + while (dasd_eer_get_free_bytes(eerb) < count + sizeof(count)) { + if (eerb->residual > 0) { + eerb->tail += eerb->residual; + if (eerb->tail >= eerb->buffersize) + eerb->tail -= eerb->buffersize; + eerb->residual = -1; + } + dasd_eer_read_buffer(eerb, (char *) &tailcount, + sizeof(tailcount)); + eerb->tail += tailcount; + if (eerb->tail >= eerb->buffersize) + eerb->tail -= eerb->buffersize; + } + dasd_eer_write_buffer(eerb, (char*) &count, sizeof(count)); + + return 0; +}; + +/* + * Release pages that are not used anymore. + */ +static void dasd_eer_free_buffer_pages(char **buf, int no_pages) +{ + int i; + + for (i = 0; i < no_pages; i++) + free_page((unsigned long) buf[i]); +} + +/* + * Allocate a new set of memory pages. + */ +static int dasd_eer_allocate_buffer_pages(char **buf, int no_pages) +{ + int i; + + for (i = 0; i < no_pages; i++) { + buf[i] = (char *) get_zeroed_page(GFP_KERNEL); + if (!buf[i]) { + dasd_eer_free_buffer_pages(buf, i); + return -ENOMEM; + } + } + return 0; +} + +/* + * SECTION: The extended error reporting functionality + */ + +/* + * When a DASD device driver wants to report an error, it calls the + * function dasd_eer_write and gives the respective trigger ID as + * parameter. Currently there are four kinds of triggers: + * + * DASD_EER_FATALERROR: all kinds of unrecoverable I/O problems + * DASD_EER_PPRCSUSPEND: PPRC was suspended + * DASD_EER_NOPATH: There is no path to the device left. + * DASD_EER_STATECHANGE: The state of the device has changed. + * + * For the first three triggers all required information can be supplied by + * the caller. For these triggers a record is written by the function + * dasd_eer_write_standard_trigger. + * + * The DASD_EER_STATECHANGE trigger is special since a sense subsystem + * status ccw need to be executed to gather the necessary sense data first. + * The dasd_eer_snss function will queue the SNSS request and the request + * callback will then call dasd_eer_write with the DASD_EER_STATCHANGE + * trigger. + * + * To avoid memory allocations at runtime, the necessary memory is allocated + * when the extended error reporting is enabled for a device (by + * dasd_eer_probe). There is one sense subsystem status request for each + * eer enabled DASD device. The presence of the cqr in device->eer_cqr + * indicates that eer is enable for the device. The use of the snss request + * is protected by the DASD_FLAG_EER_IN_USE bit. When this flag indicates + * that the cqr is currently in use, dasd_eer_snss cannot start a second + * request but sets the DASD_FLAG_EER_SNSS flag instead. The callback of + * the SNSS request will check the bit and call dasd_eer_snss again. + */ + +#define SNSS_DATA_SIZE 44 + +#define DASD_EER_BUSID_SIZE 10 +struct dasd_eer_header { + __u32 total_size; + __u32 trigger; + __u64 tv_sec; + __u64 tv_usec; + char busid[DASD_EER_BUSID_SIZE]; +}; + +/* + * The following function can be used for those triggers that have + * all necessary data available when the function is called. + * If the parameter cqr is not NULL, the chain of requests will be searched + * for valid sense data, and all valid sense data sets will be added to + * the triggers data. + */ +static void dasd_eer_write_standard_trigger(struct dasd_device *device, + struct dasd_ccw_req *cqr, + int trigger) +{ + struct dasd_ccw_req *temp_cqr; + int data_size; + struct timeval tv; + struct dasd_eer_header header; + unsigned long flags; + struct eerbuffer *eerb; + + /* go through cqr chain and count the valid sense data sets */ + data_size = 0; + for (temp_cqr = cqr; temp_cqr; temp_cqr = temp_cqr->refers) + if (temp_cqr->irb.esw.esw0.erw.cons) + data_size += 32; + + header.total_size = sizeof(header) + data_size + 4; /* "EOR" */ + header.trigger = trigger; + do_gettimeofday(&tv); + header.tv_sec = tv.tv_sec; + header.tv_usec = tv.tv_usec; + strncpy(header.busid, device->cdev->dev.bus_id, DASD_EER_BUSID_SIZE); + + spin_lock_irqsave(&bufferlock, flags); + list_for_each_entry(eerb, &bufferlist, list) { + dasd_eer_start_record(eerb, header.total_size); + dasd_eer_write_buffer(eerb, (char *) &header, sizeof(header)); + for (temp_cqr = cqr; temp_cqr; temp_cqr = temp_cqr->refers) + if (temp_cqr->irb.esw.esw0.erw.cons) + dasd_eer_write_buffer(eerb, cqr->irb.ecw, 32); + dasd_eer_write_buffer(eerb, "EOR", 4); + } + spin_unlock_irqrestore(&bufferlock, flags); + wake_up_interruptible(&dasd_eer_read_wait_queue); +} + +/* + * This function writes a DASD_EER_STATECHANGE trigger. + */ +static void dasd_eer_write_snss_trigger(struct dasd_device *device, + struct dasd_ccw_req *cqr, + int trigger) +{ + int data_size; + int snss_rc; + struct timeval tv; + struct dasd_eer_header header; + unsigned long flags; + struct eerbuffer *eerb; + + snss_rc = (cqr->status == DASD_CQR_FAILED) ? -EIO : 0; + if (snss_rc) + data_size = 0; + else + data_size = SNSS_DATA_SIZE; + + header.total_size = sizeof(header) + data_size + 4; /* "EOR" */ + header.trigger = DASD_EER_STATECHANGE; + do_gettimeofday(&tv); + header.tv_sec = tv.tv_sec; + header.tv_usec = tv.tv_usec; + strncpy(header.busid, device->cdev->dev.bus_id, DASD_EER_BUSID_SIZE); + + spin_lock_irqsave(&bufferlock, flags); + list_for_each_entry(eerb, &bufferlist, list) { + dasd_eer_start_record(eerb, header.total_size); + dasd_eer_write_buffer(eerb, (char *) &header , sizeof(header)); + if (!snss_rc) + dasd_eer_write_buffer(eerb, cqr->data, SNSS_DATA_SIZE); + dasd_eer_write_buffer(eerb, "EOR", 4); + } + spin_unlock_irqrestore(&bufferlock, flags); + wake_up_interruptible(&dasd_eer_read_wait_queue); +} + +/* + * This function is called for all triggers. It calls the appropriate + * function that writes the actual trigger records. + */ +void dasd_eer_write(struct dasd_device *device, struct dasd_ccw_req *cqr, + unsigned int id) +{ + if (!device->eer_cqr) + return; + switch (id) { + case DASD_EER_FATALERROR: + case DASD_EER_PPRCSUSPEND: + dasd_eer_write_standard_trigger(device, cqr, id); + break; + case DASD_EER_NOPATH: + dasd_eer_write_standard_trigger(device, NULL, id); + break; + case DASD_EER_STATECHANGE: + dasd_eer_write_snss_trigger(device, cqr, id); + break; + default: /* unknown trigger, so we write it without any sense data */ + dasd_eer_write_standard_trigger(device, NULL, id); + break; + } +} +EXPORT_SYMBOL(dasd_eer_write); + +/* + * Start a sense subsystem status request. + * Needs to be called with the device held. + */ +void dasd_eer_snss(struct dasd_device *device) +{ + struct dasd_ccw_req *cqr; + + cqr = device->eer_cqr; + if (!cqr) /* Device not eer enabled. */ + return; + if (test_and_set_bit(DASD_FLAG_EER_IN_USE, &device->flags)) { + /* Sense subsystem status request in use. */ + set_bit(DASD_FLAG_EER_SNSS, &device->flags); + return; + } + clear_bit(DASD_FLAG_EER_SNSS, &device->flags); + cqr->status = DASD_CQR_QUEUED; + list_add(&cqr->list, &device->ccw_queue); + dasd_schedule_bh(device); +} + +/* + * Callback function for use with sense subsystem status request. + */ +static void dasd_eer_snss_cb(struct dasd_ccw_req *cqr, void *data) +{ + struct dasd_device *device = cqr->device; + unsigned long flags; + + dasd_eer_write(device, cqr, DASD_EER_STATECHANGE); + spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + if (device->eer_cqr == cqr) { + clear_bit(DASD_FLAG_EER_IN_USE, &device->flags); + if (test_bit(DASD_FLAG_EER_SNSS, &device->flags)) + /* Another SNSS has been requested in the meantime. */ + dasd_eer_snss(device); + cqr = NULL; + } + spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); + if (cqr) + /* + * Extended error recovery has been switched off while + * the SNSS request was running. It could even have + * been switched off and on again in which case there + * is a new ccw in device->eer_cqr. Free the "old" + * snss request now. + */ + dasd_kfree_request(cqr, device); +} + +/* + * Enable error reporting on a given device. + */ +int dasd_eer_enable(struct dasd_device *device) +{ + struct dasd_ccw_req *cqr; + unsigned long flags; + + if (device->eer_cqr) + return 0; + + if (!device->discipline || strcmp(device->discipline->name, "ECKD")) + return -EPERM; /* FIXME: -EMEDIUMTYPE ? */ + + cqr = dasd_kmalloc_request("ECKD", 1 /* SNSS */, + SNSS_DATA_SIZE, device); + if (!cqr) + return -ENOMEM; + + cqr->device = device; + cqr->retries = 255; + cqr->expires = 10 * HZ; + + cqr->cpaddr->cmd_code = DASD_ECKD_CCW_SNSS; + cqr->cpaddr->count = SNSS_DATA_SIZE; + cqr->cpaddr->flags = 0; + cqr->cpaddr->cda = (__u32)(addr_t) cqr->data; + + cqr->buildclk = get_clock(); + cqr->status = DASD_CQR_FILLED; + cqr->callback = dasd_eer_snss_cb; + + spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + if (!device->eer_cqr) { + device->eer_cqr = cqr; + cqr = NULL; + } + spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); + if (cqr) + dasd_kfree_request(cqr, device); + return 0; +} + +/* + * Disable error reporting on a given device. + */ +void dasd_eer_disable(struct dasd_device *device) +{ + struct dasd_ccw_req *cqr; + unsigned long flags; + int in_use; + + if (!device->eer_cqr) + return; + spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags); + cqr = device->eer_cqr; + device->eer_cqr = NULL; + clear_bit(DASD_FLAG_EER_SNSS, &device->flags); + in_use = test_and_clear_bit(DASD_FLAG_EER_IN_USE, &device->flags); + spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags); + if (cqr && !in_use) + dasd_kfree_request(cqr, device); +} + +/* + * SECTION: the device operations + */ + +/* + * On the one side we need a lock to access our internal buffer, on the + * other side a copy_to_user can sleep. So we need to copy the data we have + * to transfer in a readbuffer, which is protected by the readbuffer_mutex. + */ +static char readbuffer[PAGE_SIZE]; +static DECLARE_MUTEX(readbuffer_mutex); + +static int dasd_eer_open(struct inode *inp, struct file *filp) +{ + struct eerbuffer *eerb; + unsigned long flags; + + eerb = kzalloc(sizeof(struct eerbuffer), GFP_KERNEL); + eerb->buffer_page_count = eer_pages; + if (eerb->buffer_page_count < 1 || + eerb->buffer_page_count > INT_MAX / PAGE_SIZE) { + kfree(eerb); + MESSAGE(KERN_WARNING, "can't open device since module " + "parameter eer_pages is smaller then 1 or" + " bigger then %d", (int)(INT_MAX / PAGE_SIZE)); + return -EINVAL; + } + eerb->buffersize = eerb->buffer_page_count * PAGE_SIZE; + eerb->buffer = kmalloc(eerb->buffer_page_count * sizeof(char *), + GFP_KERNEL); + if (!eerb->buffer) { + kfree(eerb); + return -ENOMEM; + } + if (dasd_eer_allocate_buffer_pages(eerb->buffer, + eerb->buffer_page_count)) { + kfree(eerb->buffer); + kfree(eerb); + return -ENOMEM; + } + filp->private_data = eerb; + spin_lock_irqsave(&bufferlock, flags); + list_add(&eerb->list, &bufferlist); + spin_unlock_irqrestore(&bufferlock, flags); + + return nonseekable_open(inp,filp); +} + +static int dasd_eer_close(struct inode *inp, struct file *filp) +{ + struct eerbuffer *eerb; + unsigned long flags; + + eerb = (struct eerbuffer *) filp->private_data; + spin_lock_irqsave(&bufferlock, flags); + list_del(&eerb->list); + spin_unlock_irqrestore(&bufferlock, flags); + dasd_eer_free_buffer_pages(eerb->buffer, eerb->buffer_page_count); + kfree(eerb->buffer); + kfree(eerb); + + return 0; +} + +static ssize_t dasd_eer_read(struct file *filp, char __user *buf, + size_t count, loff_t *ppos) +{ + int tc,rc; + int tailcount,effective_count; + unsigned long flags; + struct eerbuffer *eerb; + + eerb = (struct eerbuffer *) filp->private_data; + if (down_interruptible(&readbuffer_mutex)) + return -ERESTARTSYS; + + spin_lock_irqsave(&bufferlock, flags); + + if (eerb->residual < 0) { /* the remainder of this record */ + /* has been deleted */ + eerb->residual = 0; + spin_unlock_irqrestore(&bufferlock, flags); + up(&readbuffer_mutex); + return -EIO; + } else if (eerb->residual > 0) { + /* OK we still have a second half of a record to deliver */ + effective_count = min(eerb->residual, (int) count); + eerb->residual -= effective_count; + } else { + tc = 0; + while (!tc) { + tc = dasd_eer_read_buffer(eerb, (char *) &tailcount, + sizeof(tailcount)); + if (!tc) { + /* no data available */ + spin_unlock_irqrestore(&bufferlock, flags); + up(&readbuffer_mutex); + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + rc = wait_event_interruptible( + dasd_eer_read_wait_queue, + eerb->head != eerb->tail); + if (rc) + return rc; + if (down_interruptible(&readbuffer_mutex)) + return -ERESTARTSYS; + spin_lock_irqsave(&bufferlock, flags); + } + } + WARN_ON(tc != sizeof(tailcount)); + effective_count = min(tailcount,(int)count); + eerb->residual = tailcount - effective_count; + } + + tc = dasd_eer_read_buffer(eerb, readbuffer, effective_count); + WARN_ON(tc != effective_count); + + spin_unlock_irqrestore(&bufferlock, flags); + + if (copy_to_user(buf, readbuffer, effective_count)) { + up(&readbuffer_mutex); + return -EFAULT; + } + + up(&readbuffer_mutex); + return effective_count; +} + +static unsigned int dasd_eer_poll(struct file *filp, poll_table *ptable) +{ + unsigned int mask; + unsigned long flags; + struct eerbuffer *eerb; + + eerb = (struct eerbuffer *) filp->private_data; + poll_wait(filp, &dasd_eer_read_wait_queue, ptable); + spin_lock_irqsave(&bufferlock, flags); + if (eerb->head != eerb->tail) + mask = POLLIN | POLLRDNORM ; + else + mask = 0; + spin_unlock_irqrestore(&bufferlock, flags); + return mask; +} + +static struct file_operations dasd_eer_fops = { + .open = &dasd_eer_open, + .release = &dasd_eer_close, + .read = &dasd_eer_read, + .poll = &dasd_eer_poll, + .owner = THIS_MODULE, +}; + +static struct miscdevice dasd_eer_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "dasd_eer", + .fops = &dasd_eer_fops, +}; + +int __init dasd_eer_init(void) +{ + int rc; + + rc = misc_register(&dasd_eer_dev); + if (rc) { + MESSAGE(KERN_ERR, "%s", "dasd_eer_init could not " + "register misc device"); + return rc; + } + + return 0; +} + +void __exit dasd_eer_exit(void) +{ + WARN_ON(misc_deregister(&dasd_eer_dev) != 0); +} |