diff options
Diffstat (limited to 'drivers/oprofile/event_buffer.c')
| -rw-r--r-- | drivers/oprofile/event_buffer.c | 209 |
1 files changed, 0 insertions, 209 deletions
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c deleted file mode 100644 index 6c9edc8bbc95..000000000000 --- a/drivers/oprofile/event_buffer.c +++ /dev/null @@ -1,209 +0,0 @@ -/** - * @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, -}; |