tracing/boottime: Fix kprobe event API usage

Fix boottime kprobe events to use API correctly for
multiple events.

For example, when we set a multiprobe kprobe events in
bootconfig like below,

  ftrace.event.kprobes.myevent {
  	probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2"
  }

This cause an error;

  trace_boot: Failed to add probe: p:kprobes/myevent (null)  vfs_read $arg1 $arg2  vfs_write $arg1 $arg2

This shows the 1st argument becomes NULL and multiprobes
are merged to 1 probe.

Link: http://lkml.kernel.org/r/158779375766.6082.201939936008972838.stgit@devnote2
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Fixes: 29a154810546 ("tracing: Change trace_boot to use kprobe_event interface")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 06d7feb5255f88d51e80ed144ee3ef41ccb8a783..9de29bb45a27f1aae98479ff60660db2b807b4f6 100644 (file)
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -95,24 +95,20 @@ trace_boot_add_kprobe_event(struct xbc_node *node, const char *event)
        struct xbc_node *anode;
        char buf[MAX_BUF_LEN];
        const char *val;
-       int ret;
+       int ret = 0;
 
-       kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN);
+       xbc_node_for_each_array_value(node, "probes", anode, val) {
+               kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN);
 
-       ret = kprobe_event_gen_cmd_start(&cmd, event, NULL);
-       if (ret)
-               return ret;
+               ret = kprobe_event_gen_cmd_start(&cmd, event, val);
+               if (ret)
+                       break;
 
-       xbc_node_for_each_array_value(node, "probes", anode, val) {
-               ret = kprobe_event_add_field(&cmd, val);
+               ret = kprobe_event_gen_cmd_end(&cmd);
                if (ret)
-                       return ret;
+                       pr_err("Failed to add probe: %s\n", buf);
        }
 
-       ret = kprobe_event_gen_cmd_end(&cmd);
-       if (ret)
-               pr_err("Failed to add probe: %s\n", buf);
-
        return ret;
 }
 #else