+++ /dev/null
-/**
- * @file event_buffer.c
- *
- * @remark Copyright 2002 OProfile authors
- * @remark Read the file COPYING
- *
- * @author John Levon <levon@movementarian.org>
- *
- * This is the global event buffer that the user-space
- * daemon reads from. The event buffer is an untyped array
- * of unsigned longs. Entries are prefixed by the
- * escape value ESCAPE_CODE followed by an identifying code.
- */
-
-#include <linux/vmalloc.h>
-#include <linux/oprofile.h>
-#include <linux/sched/signal.h>
-#include <linux/capability.h>
-#include <linux/dcookies.h>
-#include <linux/fs.h>
-#include <linux/uaccess.h>
-
-#include "oprof.h"
-#include "event_buffer.h"
-#include "oprofile_stats.h"
-
-DEFINE_MUTEX(buffer_mutex);
-
-static unsigned long buffer_opened;
-static DECLARE_WAIT_QUEUE_HEAD(buffer_wait);
-static unsigned long *event_buffer;
-static unsigned long buffer_size;
-static unsigned long buffer_watershed;
-static size_t buffer_pos;
-/* atomic_t because wait_event checks it outside of buffer_mutex */
-static atomic_t buffer_ready = ATOMIC_INIT(0);
-
-/*
- * Add an entry to the event buffer. When we get near to the end we
- * wake up the process sleeping on the read() of the file. To protect
- * the event_buffer this function may only be called when buffer_mutex
- * is set.
- */
-void add_event_entry(unsigned long value)
-{
- /*
- * This shouldn't happen since all workqueues or handlers are
- * canceled or flushed before the event buffer is freed.
- */
- if (!event_buffer) {
- WARN_ON_ONCE(1);
- return;
- }
-
- if (buffer_pos == buffer_size) {
- atomic_inc(&oprofile_stats.event_lost_overflow);
- return;
- }
-
- event_buffer[buffer_pos] = value;
- if (++buffer_pos == buffer_size - buffer_watershed) {
- atomic_set(&buffer_ready, 1);
- wake_up(&buffer_wait);
- }
-}
-
-
-/* Wake up the waiting process if any. This happens
- * on "echo 0 >/dev/oprofile/enable" so the daemon
- * processes the data remaining in the event buffer.
- */
-void wake_up_buffer_waiter(void)
-{
- mutex_lock(&buffer_mutex);
- atomic_set(&buffer_ready, 1);
- wake_up(&buffer_wait);
- mutex_unlock(&buffer_mutex);
-}
-
-
-int alloc_event_buffer(void)
-{
- unsigned long flags;
-
- raw_spin_lock_irqsave(&oprofilefs_lock, flags);
- buffer_size = oprofile_buffer_size;
- buffer_watershed = oprofile_buffer_watershed;
- raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
-
- if (buffer_watershed >= buffer_size)
- return -EINVAL;
-
- buffer_pos = 0;
- event_buffer = vmalloc(array_size(buffer_size, sizeof(unsigned long)));
- if (!event_buffer)
- return -ENOMEM;
-
- return 0;
-}
-
-
-void free_event_buffer(void)
-{
- mutex_lock(&buffer_mutex);
- vfree(event_buffer);
- buffer_pos = 0;
- event_buffer = NULL;
- mutex_unlock(&buffer_mutex);
-}
-
-
-static int event_buffer_open(struct inode *inode, struct file *file)
-{
- int err = -EPERM;
-
- if (!perfmon_capable())
- return -EPERM;
-
- if (test_and_set_bit_lock(0, &buffer_opened))
- return -EBUSY;
-
- /* Register as a user of dcookies
- * to ensure they persist for the lifetime of
- * the open event file
- */
- err = -EINVAL;
- file->private_data = dcookie_register();
- if (!file->private_data)
- goto out;
-
- if ((err = oprofile_setup()))
- goto fail;
-
- /* NB: the actual start happens from userspace
- * echo 1 >/dev/oprofile/enable
- */
-
- return nonseekable_open(inode, file);
-
-fail:
- dcookie_unregister(file->private_data);
-out:
- __clear_bit_unlock(0, &buffer_opened);
- return err;
-}
-
-
-static int event_buffer_release(struct inode *inode, struct file *file)
-{
- oprofile_stop();
- oprofile_shutdown();
- dcookie_unregister(file->private_data);
- buffer_pos = 0;
- atomic_set(&buffer_ready, 0);
- __clear_bit_unlock(0, &buffer_opened);
- return 0;
-}
-
-
-static ssize_t event_buffer_read(struct file *file, char __user *buf,
- size_t count, loff_t *offset)
-{
- int retval = -EINVAL;
- size_t const max = buffer_size * sizeof(unsigned long);
-
- /* handling partial reads is more trouble than it's worth */
- if (count != max || *offset)
- return -EINVAL;
-
- wait_event_interruptible(buffer_wait, atomic_read(&buffer_ready));
-
- if (signal_pending(current))
- return -EINTR;
-
- /* can't currently happen */
- if (!atomic_read(&buffer_ready))
- return -EAGAIN;
-
- mutex_lock(&buffer_mutex);
-
- /* May happen if the buffer is freed during pending reads. */
- if (!event_buffer) {
- retval = -EINTR;
- goto out;
- }
-
- atomic_set(&buffer_ready, 0);
-
- retval = -EFAULT;
-
- count = buffer_pos * sizeof(unsigned long);
-
- if (copy_to_user(buf, event_buffer, count))
- goto out;
-
- retval = count;
- buffer_pos = 0;
-
-out:
- mutex_unlock(&buffer_mutex);
- return retval;
-}
-
-const struct file_operations event_buffer_fops = {
- .open = event_buffer_open,
- .release = event_buffer_release,
- .read = event_buffer_read,
- .llseek = no_llseek,
-};
projects / linux-2.6-microblaze.git / blobdiff