#define BATADV_LOG_BUFF_MASK (batadv_log_buff_len - 1)
static const int batadv_log_buff_len = BATADV_LOG_BUF_LEN;
static char *batadv_log_char_addr(struct batadv_priv_debug_log *debug_log,
size_t idx)
{
return &debug_log->log_buff[idx & BATADV_LOG_BUFF_MASK];
}
static void batadv_emit_log_char(struct batadv_priv_debug_log *debug_log,
char c)
{
char *char_addr;
char_addr = batadv_log_char_addr(debug_log, debug_log->log_end);
*char_addr = c;
debug_log->log_end++;
if (debug_log->log_end - debug_log->log_start > batadv_log_buff_len)
debug_log->log_start = debug_log->log_end - batadv_log_buff_len;
}
__printf(2, 3)
static int batadv_fdebug_log(struct batadv_priv_debug_log *debug_log,
const char *fmt, ...)
{
va_list args;
static char debug_log_buf[256];
char *p;
if (!debug_log)
return 0;
spin_lock_bh(&debug_log->lock);
va_start(args, fmt);
vscnprintf(debug_log_buf, sizeof(debug_log_buf), fmt, args);
va_end(args);
for (p = debug_log_buf; *p != 0; p++)
batadv_emit_log_char(debug_log, *p);
spin_unlock_bh(&debug_log->lock);
wake_up(&debug_log->queue_wait);
return 0;
}
int batadv_debug_log(struct batadv_priv *bat_priv, const char *fmt, ...)
{
va_list args;
char tmp_log_buf[256];
va_start(args, fmt);
vscnprintf(tmp_log_buf, sizeof(tmp_log_buf), fmt, args);
batadv_fdebug_log(bat_priv->debug_log, "[%10u] %s",
jiffies_to_msecs(jiffies), tmp_log_buf);
va_end(args);
return 0;
}
static int batadv_log_open(struct inode *inode, struct file *file)
{
if (!try_module_get(THIS_MODULE))
return -EBUSY;
nonseekable_open(inode, file);
file->private_data = inode->i_private;
return 0;
}
static int batadv_log_release(struct inode *inode, struct file *file)
{
module_put(THIS_MODULE);
return 0;
}
static bool batadv_log_empty(struct batadv_priv_debug_log *debug_log)
{
return !(debug_log->log_start - debug_log->log_end);
}
static ssize_t batadv_log_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
struct batadv_priv *bat_priv = file->private_data;
struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
int error, i = 0;
char *char_addr;
char c;
if ((file->f_flags & O_NONBLOCK) && batadv_log_empty(debug_log))
return -EAGAIN;
if (!buf)
return -EINVAL;
if (count == 0)
return 0;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
error = wait_event_interruptible(debug_log->queue_wait,
(!batadv_log_empty(debug_log)));
if (error)
return error;
spin_lock_bh(&debug_log->lock);
while ((!error) && (i < count) &&
(debug_log->log_start != debug_log->log_end)) {
char_addr = batadv_log_char_addr(debug_log,
debug_log->log_start);
c = *char_addr;
debug_log->log_start++;
spin_unlock_bh(&debug_log->lock);
error = __put_user(c, buf);
spin_lock_bh(&debug_log->lock);
buf++;
i++;
}
spin_unlock_bh(&debug_log->lock);
if (!error)
return i;
return error;
}
static unsigned int batadv_log_poll(struct file *file, poll_table *wait)
{
struct batadv_priv *bat_priv = file->private_data;
struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
poll_wait(file, &debug_log->queue_wait, wait);
if (!batadv_log_empty(debug_log))
return POLLIN | POLLRDNORM;
return 0;
}
static const struct file_operations batadv_log_fops = {
.open = batadv_log_open,
.release = batadv_log_release,
.read = batadv_log_read,
.poll = batadv_log_poll,
.llseek = no_llseek,
};
int batadv_debug_log_setup(struct batadv_priv *bat_priv)
{
struct dentry *d;
if (!bat_priv->debug_dir)
goto err;
bat_priv->debug_log = kzalloc(sizeof(*bat_priv->debug_log), GFP_ATOMIC);
if (!bat_priv->debug_log)
goto err;
spin_lock_init(&bat_priv->debug_log->lock);
init_waitqueue_head(&bat_priv->debug_log->queue_wait);
d = debugfs_create_file("log", 0400, bat_priv->debug_dir, bat_priv,
&batadv_log_fops);
if (!d)
goto err;
return 0;
err:
return -ENOMEM;
}
void batadv_debug_log_cleanup(struct batadv_priv *bat_priv)
{
kfree(bat_priv->debug_log);
bat_priv->debug_log = NULL;
}
/td>
| tree | 370efda701f03cccf21e02bb1fdd3b852547d75c /drivers/usb/core/message.c |
|---|
| parent | 0c744ea4f77d72b3dcebb7a8f2684633ec79be88 (diff) |
|---|
tracing: Fix hwlat kthread migration
The hwlat tracer creates a kernel thread at start of the tracer. It is
pinned to a single CPU and will move to the next CPU after each period of
running. If the user modifies the migration thread's affinity, it will not
change after that happens.
The original code created the thread at the first instance it was called,
but later was changed to destroy the thread after the tracer was finished,
and would not be created until the next instance of the tracer was
established. The code that initialized the affinity was only called on the
initial instantiation of the tracer. After that, it was not initialized, and
the previous affinity did not match the current newly created one, making
it appear that the user modified the thread's affinity when it did not, and
the thread failed to migrate again.
Cc: stable@vger.kernel.org
Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>