#include <linux/dcookies.h>
#include <linux/fs.h>
#include <asm/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 *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.
+/*
+ * 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;
mutex_unlock(&buffer_mutex);
}
-
+
int alloc_event_buffer(void)
{
- int err = -ENOMEM;
+ unsigned long flags;
+
+ spin_lock_irqsave(&oprofilefs_lock, flags);
+ buffer_size = oprofile_buffer_size;
+ buffer_watershed = oprofile_buffer_watershed;
+ spin_unlock_irqrestore(&oprofilefs_lock, flags);
- spin_lock(&oprofilefs_lock);
- buffer_size = fs_buffer_size;
- buffer_watershed = fs_buffer_watershed;
- spin_unlock(&oprofilefs_lock);
-
if (buffer_watershed >= buffer_size)
return -EINVAL;
-
+
+ buffer_pos = 0;
event_buffer = vmalloc(sizeof(unsigned long) * buffer_size);
if (!event_buffer)
- goto out;
+ return -ENOMEM;
- err = 0;
-out:
- return err;
+ 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)
+
+static int event_buffer_open(struct inode *inode, struct file *file)
{
int err = -EPERM;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
- if (test_and_set_bit(0, &buffer_opened))
+ if (test_and_set_bit_lock(0, &buffer_opened))
return -EBUSY;
/* Register as a user of dcookies
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 0;
fail:
dcookie_unregister(file->private_data);
out:
- clear_bit(0, &buffer_opened);
+ __clear_bit_unlock(0, &buffer_opened);
return err;
}
-static int event_buffer_release(struct inode * inode, struct file * file)
+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(0, &buffer_opened);
+ __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)
+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);
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;
}
-
-struct file_operations event_buffer_fops = {
+
+const struct file_operations event_buffer_fops = {
.open = event_buffer_open,
.release = event_buffer_release,
.read = event_buffer_read,