linux-kernel - [RFC][PATCH] tracing: Warn and notify if tracepoints are not loaded due to module taint

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Message-ID: <20140225191505.32b56105@gandalf.local.home>
Date:	Tue, 25 Feb 2014 19:15:05 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [RFC][PATCH] tracing: Warn and notify if tracepoints are not loaded
 due to module taint

[ Posting this as an RFC, but I plan on pushing it as soon as I finish
testing it ]

If a module is loaded that is tainted with anything but OOT or CRAP, then
it will not create the traceoint infrastructure for the module. There should
be a big warning when this happens instead of exiting silently.

Fixes: 97e1c18e8d17 "tracing: Kernel Tracepoints"
Cc: stable@...r.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
 kernel/tracepoint.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 29f2654..413bc06 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -641,7 +641,8 @@ static int tracepoint_module_coming(struct module *mod)
 	 * module headers (for forced load), to make sure we don't cause a crash.
 	 * Staging and out-of-tree GPL modules are fine.
 	 */
-	if (mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)))
+	if (WARN_ONCE(mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP)),
+		      "Module is tainted, disabling tracepoints"))
 		return 0;
 	mutex_lock(&tracepoints_mutex);
 	tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
-- 
1.8.5.3

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