linux-kernel - [RFC][PATCH] tracepoint: Do not waste memory on mods with no tracepoints

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Message-ID: <20140226110313.4d92fb83@gandalf.local.home>
Date:	Wed, 26 Feb 2014 11:03:13 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Peter Zijlstra <peterz@...radead.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [RFC][PATCH] tracepoint: Do not waste memory on mods with no
 tracepoints


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@...r.kernel.org # 3.2+
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 kernel/tracepoint.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 29f2654..0d4ef26 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -636,6 +636,9 @@ 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.
@@ -679,6 +682,9 @@ 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);
-- 
1.8.1.4

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