tracing/kprobes: Fix trace_probe flags on enable_trace_kprobe() failure

If enable_trace_kprobe fails to enable the probe in enable_k(ret)probe
it returns an error, but does not unset the tp flags it set previously.
This results in a probe being considered enabled and failures like being
unable to remove the probe through kprobe_events file since probes_open()
expects every probe to be disabled.

Link: http://lkml.kernel.org/r/20180725102826.8300-1-asavkov@redhat.com
Link: http://lkml.kernel.org/r/20180725142038.4765-1-asavkov@redhat.com
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 41a7dd420c57 ("tracing/kprobes: Support ftrace_event_file base multibuffer")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 21f71847294222297b92ea1bfcada6ac1ddf6537..27ace4513c43ba965f6ff0c1e7525c5daca0b47e 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -400,11 +400,10 @@ static struct trace_kprobe *find_trace_kprobe(const char *event,
 static int
 enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
 {
+       struct event_file_link *link;
        int ret = 0;
 
        if (file) {
-               struct event_file_link *link;
-
                link = kmalloc(sizeof(*link), GFP_KERNEL);
                if (!link) {
                        ret = -ENOMEM;
@@ -424,6 +423,16 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
                else
                        ret = enable_kprobe(&tk->rp.kp);
        }
+
+       if (ret) {
+               if (file) {
+                       list_del_rcu(&link->list);
+                       kfree(link);
+                       tk->tp.flags &= ~TP_FLAG_TRACE;
+               } else {
+                       tk->tp.flags &= ~TP_FLAG_PROFILE;
+               }
+       }
  out:
        return ret;
 }