tracing: Have add_tracer_options() error pass up to callers

The function add_tracer_options() can fail, but currently it is ignored.
Pass the status of add_tracer_options() up to adding a new tracer as well
as when an instance is created. Have the instance creation fail if the
add_tracer_options() fail.

Only print a warning for the top level instance, like it does with other
failures.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20251105161935.375299297@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index afeaa9a164e91a1110a3663ae31dc3b9ba282db7..ed929d331e1de7e3ed221108849ccaa3956ea307 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2302,7 +2302,7 @@ static inline int do_run_tracer_selftest(struct tracer *type)
 }
 #endif /* CONFIG_FTRACE_STARTUP_TEST */
 
-static void add_tracer_options(struct trace_array *tr, struct tracer *t);
+static int add_tracer_options(struct trace_array *tr, struct tracer *t);
 
 static void __init apply_trace_boot_options(void);
 
@@ -2353,9 +2353,14 @@ int __init register_tracer(struct tracer *type)
        if (ret < 0)
                goto out;
 
+       ret = add_tracer_options(&global_trace, type);
+       if (ret < 0) {
+               pr_warn("Failed to create tracer options for %s\n", type->name);
+               goto out;
+       }
+
        type->next = trace_types;
        trace_types = type;
-       add_tracer_options(&global_trace, type);
 
  out:
        mutex_unlock(&trace_types_lock);
@@ -6221,7 +6226,7 @@ int tracing_update_buffers(struct trace_array *tr)
 
 struct trace_option_dentry;
 
-static void
+static int
 create_trace_option_files(struct trace_array *tr, struct tracer *tracer);
 
 /*
@@ -6243,17 +6248,17 @@ static void tracing_set_nop(struct trace_array *tr)
 
 static bool tracer_options_updated;
 
-static void add_tracer_options(struct trace_array *tr, struct tracer *t)
+static int add_tracer_options(struct trace_array *tr, struct tracer *t)
 {
        /* Only enable if the directory has been created already. */
        if (!tr->dir && !(tr->flags & TRACE_ARRAY_FL_GLOBAL))
-               return;
+               return 0;
 
        /* Only create trace option files after update_tracer_options finish */
        if (!tracer_options_updated)
-               return;
+               return 0;
 
-       create_trace_option_files(tr, t);
+       return create_trace_option_files(tr, t);
 }
 
 int tracing_set_tracer(struct trace_array *tr, const char *buf)
@@ -9585,7 +9590,7 @@ create_trace_option_file(struct trace_array *tr,
 
 }
 
-static void
+static int
 create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 {
        struct trace_option_dentry *topts;
@@ -9596,24 +9601,24 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
        int i;
 
        if (!tracer)
-               return;
+               return 0;
 
        flags = tracer->flags;
 
        if (!flags || !flags->opts)
-               return;
+               return 0;
 
        /*
         * If this is an instance, only create flags for tracers
         * the instance may have.
         */
        if (!trace_ok_for_array(tracer, tr))
-               return;
+               return 0;
 
        for (i = 0; i < tr->nr_topts; i++) {
                /* Make sure there's no duplicate flags. */
                if (WARN_ON_ONCE(tr->topts[i].tracer->flags == tracer->flags))
-                       return;
+                       return -EINVAL;
        }
 
        opts = flags->opts;
@@ -9623,13 +9628,13 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 
        topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
        if (!topts)
-               return;
+               return 0;
 
        tr_topts = krealloc(tr->topts, sizeof(*tr->topts) * (tr->nr_topts + 1),
                            GFP_KERNEL);
        if (!tr_topts) {
                kfree(topts);
-               return;
+               return -ENOMEM;
        }
 
        tr->topts = tr_topts;
@@ -9644,6 +9649,7 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
                          "Failed to create trace option: %s",
                          opts[cnt].name);
        }
+       return 0;
 }
 
 static struct dentry *
@@ -10094,15 +10100,18 @@ static void init_trace_flags_index(struct trace_array *tr)
                tr->trace_flags_index[i] = i;
 }
 
-static void __update_tracer_options(struct trace_array *tr)
+static int __update_tracer_options(struct trace_array *tr)
 {
        struct tracer *t;
+       int ret = 0;
+
+       for (t = trace_types; t && !ret; t = t->next)
+               ret = add_tracer_options(tr, t);
 
-       for (t = trace_types; t; t = t->next)
-               add_tracer_options(tr, t);
+       return ret;
 }
 
-static void update_tracer_options(struct trace_array *tr)
+static __init void update_tracer_options(struct trace_array *tr)
 {
        guard(mutex)(&trace_types_lock);
        tracer_options_updated = true;
@@ -10151,9 +10160,13 @@ static int trace_array_create_dir(struct trace_array *tr)
        }
 
        init_tracer_tracefs(tr, tr->dir);
-       __update_tracer_options(tr);
-
-       return ret;
+       ret = __update_tracer_options(tr);
+       if (ret) {
+               event_trace_del_tracer(tr);
+               tracefs_remove(tr->dir);
+               return ret;
+       }
+       return 0;
 }
 
 static struct trace_array *