[bug report] function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously

[Dan Carpenter <dan.carpenter@linaro.org>]

Hello pengdonglin,

Commit f83ac7544fbf ("function_graph: Enable funcgraph-args and
funcgraph-retaddr to work simultaneously") from Nov 25, 2025
(linux-next), leads to the following Smatch static checker warning:

kernel/trace/trace_functions_graph.c:1033 print_graph_entry_nested() warn: unsigned 'call->depth' is never less than zero.
kernel/trace/trace_functions_graph.c:975 print_graph_entry_leaf() warn: unsigned 'call->depth' is never less than zero.
kernel/trace/trace.h:1130 ftrace_graph_ignore_func() warn: unsigned 'trace->depth' is never less than zero.

kernel/trace/trace_functions_graph.c
    1012 static enum print_line_t
    1013 print_graph_entry_nested(struct trace_iterator *iter,
    1014                          struct ftrace_graph_ent_entry *entry,
    1015                          struct trace_seq *s, int cpu, u32 flags)
    1016 {
    1017         struct ftrace_graph_ent *call = &entry->graph_ent;
    1018         struct fgraph_data *data = iter->private;
    1019         struct trace_array *tr = iter->tr;
    1020         unsigned long func;
    1021         int args_size;
    1022         int i;
    1023 
    1024         if (data) {
    1025                 struct fgraph_cpu_data *cpu_data;
    1026                 int cpu = iter->cpu;
    1027 
    1028                 cpu_data = per_cpu_ptr(data->cpu_data, cpu);
    1029                 cpu_data->depth = call->depth;
    1030 
    1031                 /* Save this function pointer to see if the exit matches */
    1032                 if (call->depth < FTRACE_RETFUNC_DEPTH &&
--> 1033                     !WARN_ON_ONCE(call->depth < 0))
                                           ^^^^^^^^^^^^^^^
The patch changed call->depth from int to unsigned long.

    1034                         cpu_data->enter_funcs[call->depth] = call->func;
    1035         }
    1036 
    1037         /* No time */
    1038         print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL);

regards,
dan carpenter