linux-kernel - [PATCH 4/8] clocksource/drivers/prima2: Prevent ftrace recursion

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Date:	Wed, 28 Oct 2015 14:11:29 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	tglx@...utronix.de
Cc:	Jisheng Zhang <jszhang@...vell.com>,
	Barry Song <baohua@...nel.org>,
	linux-arm-kernel@...ts.infradead.org (moderated list:ARM/CSR
	SIRFPRIMA...),
	linux-kernel@...r.kernel.org (open list:CLOCKSOURCE, CLOC...)
Subject: [PATCH 4/8] clocksource/drivers/prima2: Prevent ftrace recursion

From: Jisheng Zhang <jszhang@...vell.com>

Currently prima2 timer can be used as a scheduler clock. We properly
marked sirfsoc_read_sched_clock() as notrace but we then call another
function sirfsoc_timer_read() that _wasn't_ notrace.

Having a traceable function in the sched_clock() path leads to a recursion
within ftrace and a kernel crash.

Fix this by adding notrace attribute to the sirfsoc_timer_read() function.

Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 drivers/clocksource/timer-prima2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-prima2.c b/drivers/clocksource/timer-prima2.c
index 78de982..2854c66 100644
--- a/drivers/clocksource/timer-prima2.c
+++ b/drivers/clocksource/timer-prima2.c
@@ -73,7 +73,7 @@ static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id)
 }
 
 /* read 64-bit timer counter */
-static cycle_t sirfsoc_timer_read(struct clocksource *cs)
+static cycle_t notrace sirfsoc_timer_read(struct clocksource *cs)
 {
 	u64 cycles;
 
-- 
1.9.1

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