tracing/kprobes: Support soft-mode disabling

Support soft-mode disabling on kprobe-based dynamic events.
Soft-disabling is just ignoring recording if the soft disabled
flag is set.

Link: http://lkml.kernel.org/r/20130509054454.30398.7237.stgit@mhiramat-M0-7522

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Tom Zanussi <tom.zanussi@intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index fee865d8a7c4..636d45fe69b3 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -845,6 +845,9 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
 
         WARN_ON(call != ftrace_file->event_call);
 
+        if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
+                return;
+
         local_save_flags(irq_flags);
         pc = preempt_count();
 
@@ -893,6 +896,9 @@ __kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
 
         WARN_ON(call != ftrace_file->event_call);
 
+        if (test_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &ftrace_file->flags))
+                return;
+
         local_save_flags(irq_flags);
         pc = preempt_count();