tracing: add lock depth to entries
This patch adds the lock depth of the big kernel lock to the generic
entry header. This way we can see the depth of the lock and help
in removing the BKL.
Example:
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /_--=> lock-depth
# |||||/ delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
<idle>-0 2.N..3 5902255250us+: lock_acquire: read rcu_read_lock
<idle>-0 2.N..3 5902255253us+: lock_release: rcu_read_lock
<idle>-0 2dN..3 5902255257us+: lock_acquire: xtime_lock
<idle>-0 2dN..4 5902255259us : lock_acquire: clocksource_lock
<idle>-0 2dN..4 5902255261us+: lock_release: clocksource_lock
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1a37da2..3b91828 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -886,6 +886,7 @@
entry->preempt_count = pc & 0xff;
entry->pid = (tsk) ? tsk->pid : 0;
+ entry->lock_depth = (tsk) ? tsk->lock_depth : 0;
entry->flags =
#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
(irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
@@ -1530,10 +1531,10 @@
seq_puts(m, "# | / _----=> need-resched \n");
seq_puts(m, "# || / _---=> hardirq/softirq \n");
seq_puts(m, "# ||| / _--=> preempt-depth \n");
- seq_puts(m, "# |||| / \n");
- seq_puts(m, "# ||||| delay \n");
- seq_puts(m, "# cmd pid ||||| time | caller \n");
- seq_puts(m, "# \\ / ||||| \\ | / \n");
+ seq_puts(m, "# |||| /_--=> lock-depth \n");
+ seq_puts(m, "# |||||/ delay \n");
+ seq_puts(m, "# cmd pid |||||| time | caller \n");
+ seq_puts(m, "# \\ / |||||| \\ | / \n");
}
static void print_func_help_header(struct seq_file *m)