diff options
Diffstat (limited to 'drivers/staging/android/logger.c')
-rw-r--r-- | drivers/staging/android/logger.c | 607 |
1 files changed, 0 insertions, 607 deletions
diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c deleted file mode 100644 index 6c10b456c6c..00000000000 --- a/drivers/staging/android/logger.c +++ /dev/null @@ -1,607 +0,0 @@ -/* - * drivers/misc/logger.c - * - * A Logging Subsystem - * - * Copyright (C) 2007-2008 Google, Inc. - * - * Robert Love <rlove@google.com> - * - * This software is licensed under the terms of the GNU General Public - * License version 2, as published by the Free Software Foundation, and - * may be copied, distributed, and modified under those terms. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - */ - -#include <linux/module.h> -#include <linux/fs.h> -#include <linux/miscdevice.h> -#include <linux/uaccess.h> -#include <linux/poll.h> -#include <linux/time.h> -#include "logger.h" - -#include <asm/ioctls.h> - -/* - * struct logger_log - represents a specific log, such as 'main' or 'radio' - * - * This structure lives from module insertion until module removal, so it does - * not need additional reference counting. The structure is protected by the - * mutex 'mutex'. - */ -struct logger_log { - unsigned char *buffer;/* the ring buffer itself */ - struct miscdevice misc; /* misc device representing the log */ - wait_queue_head_t wq; /* wait queue for readers */ - struct list_head readers; /* this log's readers */ - struct mutex mutex; /* mutex protecting buffer */ - size_t w_off; /* current write head offset */ - size_t head; /* new readers start here */ - size_t size; /* size of the log */ -}; - -/* - * struct logger_reader - a logging device open for reading - * - * This object lives from open to release, so we don't need additional - * reference counting. The structure is protected by log->mutex. - */ -struct logger_reader { - struct logger_log *log; /* associated log */ - struct list_head list; /* entry in logger_log's list */ - size_t r_off; /* current read head offset */ -}; - -/* logger_offset - returns index 'n' into the log via (optimized) modulus */ -#define logger_offset(n) ((n) & (log->size - 1)) - -/* - * file_get_log - Given a file structure, return the associated log - * - * This isn't aesthetic. We have several goals: - * - * 1) Need to quickly obtain the associated log during an I/O operation - * 2) Readers need to maintain state (logger_reader) - * 3) Writers need to be very fast (open() should be a near no-op) - * - * In the reader case, we can trivially go file->logger_reader->logger_log. - * For a writer, we don't want to maintain a logger_reader, so we just go - * file->logger_log. Thus what file->private_data points at depends on whether - * or not the file was opened for reading. This function hides that dirtiness. - */ -static inline struct logger_log *file_get_log(struct file *file) -{ - if (file->f_mode & FMODE_READ) { - struct logger_reader *reader = file->private_data; - return reader->log; - } else - return file->private_data; -} - -/* - * get_entry_len - Grabs the length of the payload of the next entry starting - * from 'off'. - * - * Caller needs to hold log->mutex. - */ -static __u32 get_entry_len(struct logger_log *log, size_t off) -{ - __u16 val; - - switch (log->size - off) { - case 1: - memcpy(&val, log->buffer + off, 1); - memcpy(((char *) &val) + 1, log->buffer, 1); - break; - default: - memcpy(&val, log->buffer + off, 2); - } - - return sizeof(struct logger_entry) + val; -} - -/* - * do_read_log_to_user - reads exactly 'count' bytes from 'log' into the - * user-space buffer 'buf'. Returns 'count' on success. - * - * Caller must hold log->mutex. - */ -static ssize_t do_read_log_to_user(struct logger_log *log, - struct logger_reader *reader, - char __user *buf, - size_t count) -{ - size_t len; - - /* - * We read from the log in two disjoint operations. First, we read from - * the current read head offset up to 'count' bytes or to the end of - * the log, whichever comes first. - */ - len = min(count, log->size - reader->r_off); - if (copy_to_user(buf, log->buffer + reader->r_off, len)) - return -EFAULT; - - /* - * Second, we read any remaining bytes, starting back at the head of - * the log. - */ - if (count != len) - if (copy_to_user(buf + len, log->buffer, count - len)) - return -EFAULT; - - reader->r_off = logger_offset(reader->r_off + count); - - return count; -} - -/* - * logger_read - our log's read() method - * - * Behavior: - * - * - O_NONBLOCK works - * - If there are no log entries to read, blocks until log is written to - * - Atomically reads exactly one log entry - * - * Optimal read size is LOGGER_ENTRY_MAX_LEN. Will set errno to EINVAL if read - * buffer is insufficient to hold next entry. - */ -static ssize_t logger_read(struct file *file, char __user *buf, - size_t count, loff_t *pos) -{ - struct logger_reader *reader = file->private_data; - struct logger_log *log = reader->log; - ssize_t ret; - DEFINE_WAIT(wait); - -start: - while (1) { - prepare_to_wait(&log->wq, &wait, TASK_INTERRUPTIBLE); - - mutex_lock(&log->mutex); - ret = (log->w_off == reader->r_off); - mutex_unlock(&log->mutex); - if (!ret) - break; - - if (file->f_flags & O_NONBLOCK) { - ret = -EAGAIN; - break; - } - - if (signal_pending(current)) { - ret = -EINTR; - break; - } - - schedule(); - } - - finish_wait(&log->wq, &wait); - if (ret) - return ret; - - mutex_lock(&log->mutex); - - /* is there still something to read or did we race? */ - if (unlikely(log->w_off == reader->r_off)) { - mutex_unlock(&log->mutex); - goto start; - } - - /* get the size of the next entry */ - ret = get_entry_len(log, reader->r_off); - if (count < ret) { - ret = -EINVAL; - goto out; - } - - /* get exactly one entry from the log */ - ret = do_read_log_to_user(log, reader, buf, ret); - -out: - mutex_unlock(&log->mutex); - - return ret; -} - -/* - * get_next_entry - return the offset of the first valid entry at least 'len' - * bytes after 'off'. - * - * Caller must hold log->mutex. - */ -static size_t get_next_entry(struct logger_log *log, size_t off, size_t len) -{ - size_t count = 0; - - do { - size_t nr = get_entry_len(log, off); - off = logger_offset(off + nr); - count += nr; - } while (count < len); - - return off; -} - -/* - * clock_interval - is a < c < b in mod-space? Put another way, does the line - * from a to b cross c? - */ -static inline int clock_interval(size_t a, size_t b, size_t c) -{ - if (b < a) { - if (a < c || b >= c) - return 1; - } else { - if (a < c && b >= c) - return 1; - } - - return 0; -} - -/* - * fix_up_readers - walk the list of all readers and "fix up" any who were - * lapped by the writer; also do the same for the default "start head". - * We do this by "pulling forward" the readers and start head to the first - * entry after the new write head. - * - * The caller needs to hold log->mutex. - */ -static void fix_up_readers(struct logger_log *log, size_t len) -{ - size_t old = log->w_off; - size_t new = logger_offset(old + len); - struct logger_reader *reader; - - if (clock_interval(old, new, log->head)) - log->head = get_next_entry(log, log->head, len); - - list_for_each_entry(reader, &log->readers, list) - if (clock_interval(old, new, reader->r_off)) - reader->r_off = get_next_entry(log, reader->r_off, len); -} - -/* - * do_write_log - writes 'len' bytes from 'buf' to 'log' - * - * The caller needs to hold log->mutex. - */ -static void do_write_log(struct logger_log *log, const void *buf, size_t count) -{ - size_t len; - - len = min(count, log->size - log->w_off); - memcpy(log->buffer + log->w_off, buf, len); - - if (count != len) - memcpy(log->buffer, buf + len, count - len); - - log->w_off = logger_offset(log->w_off + count); - -} - -/* - * do_write_log_user - writes 'len' bytes from the user-space buffer 'buf' to - * the log 'log' - * - * The caller needs to hold log->mutex. - * - * Returns 'count' on success, negative error code on failure. - */ -static ssize_t do_write_log_from_user(struct logger_log *log, - const void __user *buf, size_t count) -{ - size_t len; - - len = min(count, log->size - log->w_off); - if (len && copy_from_user(log->buffer + log->w_off, buf, len)) - return -EFAULT; - - if (count != len) - if (copy_from_user(log->buffer, buf + len, count - len)) - return -EFAULT; - - log->w_off = logger_offset(log->w_off + count); - - return count; -} - -/* - * logger_aio_write - our write method, implementing support for write(), - * writev(), and aio_write(). Writes are our fast path, and we try to optimize - * them above all else. - */ -ssize_t logger_aio_write(struct kiocb *iocb, const struct iovec *iov, - unsigned long nr_segs, loff_t ppos) -{ - struct logger_log *log = file_get_log(iocb->ki_filp); - size_t orig = log->w_off; - struct logger_entry header; - struct timespec now; - ssize_t ret = 0; - - now = current_kernel_time(); - - header.pid = current->tgid; - header.tid = current->pid; - header.sec = now.tv_sec; - header.nsec = now.tv_nsec; - header.len = min_t(size_t, iocb->ki_left, LOGGER_ENTRY_MAX_PAYLOAD); - - /* null writes succeed, return zero */ - if (unlikely(!header.len)) - return 0; - - mutex_lock(&log->mutex); - - /* - * Fix up any readers, pulling them forward to the first readable - * entry after (what will be) the new write offset. We do this now - * because if we partially fail, we can end up with clobbered log - * entries that encroach on readable buffer. - */ - fix_up_readers(log, sizeof(struct logger_entry) + header.len); - - do_write_log(log, &header, sizeof(struct logger_entry)); - - while (nr_segs-- > 0) { - size_t len; - ssize_t nr; - - /* figure out how much of this vector we can keep */ - len = min_t(size_t, iov->iov_len, header.len - ret); - - /* write out this segment's payload */ - nr = do_write_log_from_user(log, iov->iov_base, len); - if (unlikely(nr < 0)) { - log->w_off = orig; - mutex_unlock(&log->mutex); - return nr; - } - - iov++; - ret += nr; - } - - mutex_unlock(&log->mutex); - - /* wake up any blocked readers */ - wake_up_interruptible(&log->wq); - - return ret; -} - -static struct logger_log *get_log_from_minor(int); - -/* - * logger_open - the log's open() file operation - * - * Note how near a no-op this is in the write-only case. Keep it that way! - */ -static int logger_open(struct inode *inode, struct file *file) -{ - struct logger_log *log; - int ret; - - ret = nonseekable_open(inode, file); - if (ret) - return ret; - - log = get_log_from_minor(MINOR(inode->i_rdev)); - if (!log) - return -ENODEV; - - if (file->f_mode & FMODE_READ) { - struct logger_reader *reader; - - reader = kmalloc(sizeof(struct logger_reader), GFP_KERNEL); - if (!reader) - return -ENOMEM; - - reader->log = log; - INIT_LIST_HEAD(&reader->list); - - mutex_lock(&log->mutex); - reader->r_off = log->head; - list_add_tail(&reader->list, &log->readers); - mutex_unlock(&log->mutex); - - file->private_data = reader; - } else - file->private_data = log; - - return 0; -} - -/* - * logger_release - the log's release file operation - * - * Note this is a total no-op in the write-only case. Keep it that way! - */ -static int logger_release(struct inode *ignored, struct file *file) -{ - if (file->f_mode & FMODE_READ) { - struct logger_reader *reader = file->private_data; - list_del(&reader->list); - kfree(reader); - } - - return 0; -} - -/* - * logger_poll - the log's poll file operation, for poll/select/epoll - * - * Note we always return POLLOUT, because you can always write() to the log. - * Note also that, strictly speaking, a return value of POLLIN does not - * guarantee that the log is readable without blocking, as there is a small - * chance that the writer can lap the reader in the interim between poll() - * returning and the read() request. - */ -static unsigned int logger_poll(struct file *file, poll_table *wait) -{ - struct logger_reader *reader; - struct logger_log *log; - unsigned int ret = POLLOUT | POLLWRNORM; - - if (!(file->f_mode & FMODE_READ)) - return ret; - - reader = file->private_data; - log = reader->log; - - poll_wait(file, &log->wq, wait); - - mutex_lock(&log->mutex); - if (log->w_off != reader->r_off) - ret |= POLLIN | POLLRDNORM; - mutex_unlock(&log->mutex); - - return ret; -} - -static long logger_ioctl(struct file *file, unsigned int cmd, unsigned long arg) -{ - struct logger_log *log = file_get_log(file); - struct logger_reader *reader; - long ret = -ENOTTY; - - mutex_lock(&log->mutex); - - switch (cmd) { - case LOGGER_GET_LOG_BUF_SIZE: - ret = log->size; - break; - case LOGGER_GET_LOG_LEN: - if (!(file->f_mode & FMODE_READ)) { - ret = -EBADF; - break; - } - reader = file->private_data; - if (log->w_off >= reader->r_off) - ret = log->w_off - reader->r_off; - else - ret = (log->size - reader->r_off) + log->w_off; - break; - case LOGGER_GET_NEXT_ENTRY_LEN: - if (!(file->f_mode & FMODE_READ)) { - ret = -EBADF; - break; - } - reader = file->private_data; - if (log->w_off != reader->r_off) - ret = get_entry_len(log, reader->r_off); - else - ret = 0; - break; - case LOGGER_FLUSH_LOG: - if (!(file->f_mode & FMODE_WRITE)) { - ret = -EBADF; - break; - } - list_for_each_entry(reader, &log->readers, list) - reader->r_off = log->w_off; - log->head = log->w_off; - ret = 0; - break; - } - - mutex_unlock(&log->mutex); - - return ret; -} - -static const struct file_operations logger_fops = { - .owner = THIS_MODULE, - .read = logger_read, - .aio_write = logger_aio_write, - .poll = logger_poll, - .unlocked_ioctl = logger_ioctl, - .compat_ioctl = logger_ioctl, - .open = logger_open, - .release = logger_release, -}; - -/* - * Defines a log structure with name 'NAME' and a size of 'SIZE' bytes, which - * must be a power of two, greater than LOGGER_ENTRY_MAX_LEN, and less than - * LONG_MAX minus LOGGER_ENTRY_MAX_LEN. - */ -#define DEFINE_LOGGER_DEVICE(VAR, NAME, SIZE) \ -static unsigned char _buf_ ## VAR[SIZE]; \ -static struct logger_log VAR = { \ - .buffer = _buf_ ## VAR, \ - .misc = { \ - .minor = MISC_DYNAMIC_MINOR, \ - .name = NAME, \ - .fops = &logger_fops, \ - .parent = NULL, \ - }, \ - .wq = __WAIT_QUEUE_HEAD_INITIALIZER(VAR .wq), \ - .readers = LIST_HEAD_INIT(VAR .readers), \ - .mutex = __MUTEX_INITIALIZER(VAR .mutex), \ - .w_off = 0, \ - .head = 0, \ - .size = SIZE, \ -}; - -DEFINE_LOGGER_DEVICE(log_main, LOGGER_LOG_MAIN, 64*1024) -DEFINE_LOGGER_DEVICE(log_events, LOGGER_LOG_EVENTS, 256*1024) -DEFINE_LOGGER_DEVICE(log_radio, LOGGER_LOG_RADIO, 64*1024) - -static struct logger_log *get_log_from_minor(int minor) -{ - if (log_main.misc.minor == minor) - return &log_main; - if (log_events.misc.minor == minor) - return &log_events; - if (log_radio.misc.minor == minor) - return &log_radio; - return NULL; -} - -static int __init init_log(struct logger_log *log) -{ - int ret; - - ret = misc_register(&log->misc); - if (unlikely(ret)) { - printk(KERN_ERR "logger: failed to register misc " - "device for log '%s'!\n", log->misc.name); - return ret; - } - - printk(KERN_INFO "logger: created %luK log '%s'\n", - (unsigned long) log->size >> 10, log->misc.name); - - return 0; -} - -static int __init logger_init(void) -{ - int ret; - - ret = init_log(&log_main); - if (unlikely(ret)) - goto out; - - ret = init_log(&log_events); - if (unlikely(ret)) - goto out; - - ret = init_log(&log_radio); - if (unlikely(ret)) - goto out; - -out: - return ret; -} -device_initcall(logger_init); |