tracing/probes: Fix not to count error code to total length

Fix not to count the error code (which is minus value) to the total
used length of array, because it can mess up the return code of
process_fetch_insn_bottom(). Also clear the 'ret' value because it
will be used for calculating next data_loc entry.

Link: https://lore.kernel.org/all/168908493827.123124.2175257289106364229.stgit@devnote2/
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/8819b154-2ba1-43c3-98a2-cbde20892023@moroto.mountain/
Fixes: 9b960a38835f ("tracing: probeevent: Unify fetch_insn processing common part")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 4735c5c..ed9d57c 100644 (file)
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -204,6 +204,8 @@ stage3:
 array:
        /* the last stage: Loop on array */
        if (code->op == FETCH_OP_LP_ARRAY) {
+               if (ret < 0)
+                       ret = 0;
                total += ret;
                if (++i < code->param) {
                        code = s3;