Merge tag 'trace-fixes-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt:
"A regression showed up that there's a large delay when enabling all
events. This was prevalent when FTRACE_SELFTEST was enabled which
enables all events several times, and caused the system bootup to
pause for over a minute.
This was tracked down to an addition of a synchronize_sched()
performed when system call tracepoints are unregistered.
The synchronize_sched() is needed between the unregistering of the
system call tracepoint and a deletion of a tracing instance buffer.
But placing the synchronize_sched() in the unreg of *every* system
call tracepoint is a bit overboard. A single synchronize_sched()
before the deletion of the instance is sufficient"
* tag 'trace-fixes-3.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Only run synchronize_sched() at instance deletion time
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index f919a2e..a11800a 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2314,6 +2314,9 @@
/* Disable any running events */
__ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);
+ /* Access to events are within rcu_read_lock_sched() */
+ synchronize_sched();
+
down_write(&trace_event_sem);
__trace_remove_event_dirs(tr);
debugfs_remove_recursive(tr->event_dir);
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index e4b6d11..ea90eb5 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -431,11 +431,6 @@
if (!tr->sys_refcount_enter)
unregister_trace_sys_enter(ftrace_syscall_enter, tr);
mutex_unlock(&syscall_trace_lock);
- /*
- * Callers expect the event to be completely disabled on
- * return, so wait for current handlers to finish.
- */
- synchronize_sched();
}
static int reg_event_syscall_exit(struct ftrace_event_file *file,
@@ -474,11 +469,6 @@
if (!tr->sys_refcount_exit)
unregister_trace_sys_exit(ftrace_syscall_exit, tr);
mutex_unlock(&syscall_trace_lock);
- /*
- * Callers expect the event to be completely disabled on
- * return, so wait for current handlers to finish.
- */
- synchronize_sched();
}
static int __init init_syscall_trace(struct ftrace_event_call *call)
