diff options
author | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-30 20:18:14 +0900 |
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committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-30 20:18:14 +0900 |
commit | 355b0502f6efea0ff9492753888772c96972d2a3 (patch) | |
tree | ff53345adb43e420ff3236979cfde8b23c464c4e /drivers/staging/android/logger.c | |
parent | 3d461c912462b6b36ff9cf2c2f605ef37aeab438 (diff) | |
download | op-kernel-dev-355b0502f6efea0ff9492753888772c96972d2a3.zip op-kernel-dev-355b0502f6efea0ff9492753888772c96972d2a3.tar.gz |
Revert "Staging: android: delete android drivers"
This reverts commit b0a0ccfad85b3657fe999805df65f5cfe634ab8a.
Turns out I was wrong, we want these in the tree.
Note, I've disabled the drivers from the build at the moment, so other
patches can be applied to fix some build issues due to internal api
changes since the code was removed from the tree.
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Brian Swetland <swetland@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/staging/android/logger.c')
-rw-r--r-- | drivers/staging/android/logger.c | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/drivers/staging/android/logger.c b/drivers/staging/android/logger.c new file mode 100644 index 0000000..6c10b45 --- /dev/null +++ b/drivers/staging/android/logger.c @@ -0,0 +1,607 @@ +/* + * 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); |