[RFA][PATCH 4/5] tracepoint: Do not waste memory on mods with no tracepoints

[Steven Rostedt <rostedt@goodmis.org>]

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[ Note, this is marked stable as the next patch requires it ]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

No reason to allocate tp_module structures for modules that have no
tracepoints. This just wastes memory.

Fixes: b75ef8b44b1c "Tracepoint: Dissociate from module mutex"
Cc: stable@vger.kernel.org # 3.2+
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/tracepoint.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 031cc56..63630ae 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -641,6 +641,9 @@ static int tracepoint_module_coming(struct module *mod)
 	struct tp_module *tp_mod, *iter;
 	int ret = 0;
 
+	if (!mod->num_tracepoints)
+		return 0;
+
 	/*
 	 * We skip modules that taint the kernel, especially those with different
 	 * module headers (for forced load), to make sure we don't cause a crash.
@@ -684,6 +687,9 @@ static int tracepoint_module_going(struct module *mod)
 {
 	struct tp_module *pos;
 
+	if (!mod->num_tracepoints)
+		return 0;
+
 	mutex_lock(&tracepoints_mutex);
 	tracepoint_update_probe_range(mod->tracepoints_ptrs,
 		mod->tracepoints_ptrs + mod->num_tracepoints);
-- 
1.8.5.3