From c7bed15ccf238fb2e47938c522a49ddc4a919f7d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 5 Nov 2025 11:19:10 -0500 Subject: [PATCH] tracing: Remove dummy options and flags When a tracer does not define their own flags, dummy options and flags are used so that the values are always valid. There's not that many locations that reference these values so having dummy versions just complicates the code. Remove the dummy values and just check for NULL when appropriate. Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Link: https://patch.msgid.link/20251105161935.206093132@kernel.org Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 48 +++++++++++++++----------------------------- 1 file changed, 16 insertions(+), 32 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0e822db5d9e42..afeaa9a164e91 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -94,17 +94,6 @@ static bool tracepoint_printk_stop_on_boot __initdata; static bool traceoff_after_boot __initdata; static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key); -/* For tracers that don't implement custom flags */ -static struct tracer_opt dummy_tracer_opt[] = { - { } -}; - -static int -dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) -{ - return 0; -} - /* * To prevent the comm cache from being overwritten when no * tracing is active, only save the comm when a trace event @@ -2356,23 +2345,9 @@ int __init register_tracer(struct tracer *type) } } - if (!type->set_flag) - type->set_flag = &dummy_set_flag; - if (!type->flags) { - /*allocate a dummy tracer_flags*/ - type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL); - if (!type->flags) { - ret = -ENOMEM; - goto out; - } - type->flags->val = 0; - type->flags->opts = dummy_tracer_opt; - } else - if (!type->flags->opts) - type->flags->opts = dummy_tracer_opt; - /* store the tracer for __set_tracer_option */ - type->flags->trace = type; + if (type->flags) + type->flags->trace = type; ret = do_run_tracer_selftest(type); if (ret < 0) @@ -5159,14 +5134,12 @@ static int tracing_trace_options_show(struct seq_file *m, void *v) { struct tracer_opt *trace_opts; struct trace_array *tr = m->private; + struct tracer *trace; u32 tracer_flags; int i; guard(mutex)(&trace_types_lock); - tracer_flags = tr->current_trace->flags->val; - trace_opts = tr->current_trace->flags->opts; - for (i = 0; trace_options[i]; i++) { if (tr->trace_flags & (1ULL << i)) seq_printf(m, "%s\n", trace_options[i]); @@ -5174,6 +5147,13 @@ static int tracing_trace_options_show(struct seq_file *m, void *v) seq_printf(m, "no%s\n", trace_options[i]); } + trace = tr->current_trace; + if (!trace->flags || !trace->flags->opts) + return 0; + + tracer_flags = tr->current_trace->flags->val; + trace_opts = tr->current_trace->flags->opts; + for (i = 0; trace_opts[i].name; i++) { if (tracer_flags & trace_opts[i].bit) seq_printf(m, "%s\n", trace_opts[i].name); @@ -5189,9 +5169,10 @@ static int __set_tracer_option(struct trace_array *tr, struct tracer_opt *opts, int neg) { struct tracer *trace = tracer_flags->trace; - int ret; + int ret = 0; - ret = trace->set_flag(tr, tracer_flags->val, opts->bit, !neg); + if (trace->set_flag) + ret = trace->set_flag(tr, tracer_flags->val, opts->bit, !neg); if (ret) return ret; @@ -5210,6 +5191,9 @@ static int set_tracer_option(struct trace_array *tr, char *cmp, int neg) struct tracer_opt *opts = NULL; int i; + if (!tracer_flags || !tracer_flags->opts) + return 0; + for (i = 0; tracer_flags->opts[i].name; i++) { opts = &tracer_flags->opts[i]; -- 2.47.3