tracing/probes: Fix to update dynamic data counter if fetcharg uses it

commit e38e2c6a9e upstream.

Fix to update dynamic data counter ('dyndata') and max length ('maxlen')
only if the fetcharg uses the dynamic data. Also get out arg->dynamic
from unlikely(). This makes dynamic data address wrong if
process_fetch_insn() returns error on !arg->dynamic case.

Link: https://lore.kernel.org/all/168908494781.123124.8160245359962103684.stgit@devnote2/

Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/all/20230710233400.5aaf024e@gandalf.local.home/
Fixes: 9178412ddf ("tracing: probeevent: Return consumed bytes of dynamic area")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/trace/trace_probe_tmpl.h

@@ -206,11 +206,13 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec,
 		if (unlikely(arg->dynamic))
 			*dl = make_data_loc(maxlen, dyndata - base);
 		ret = process_fetch_insn(arg->code, rec, dl, base);
-		if (unlikely(ret < 0 && arg->dynamic)) {
-			*dl = make_data_loc(0, dyndata - base);
-		} else {
-			dyndata += ret;
-			maxlen -= ret;
+		if (arg->dynamic) {
+			if (unlikely(ret < 0)) {
+				*dl = make_data_loc(0, dyndata - base);
+			} else {
+				dyndata += ret;
+				maxlen -= ret;
+			}
 		}
 	}
 }