[PATCH] clocksource/drivers/atmel-st: Fix sclk reference leak in error paths

[Wentao Liang]

atmel_st_timer_init() obtains the slow clock with of_clk_get() but never
releases the reference on error. If clk_prepare_enable() fails the
reference is leaked directly, and if the clock rate is invalid or
clocksource_register_hz() fails the error paths return without disabling
or putting the already enabled clock.

Add the missing cleanup to the three error paths: clk_put() when
prepare+enable fails, and clk_disable_unprepare() followed by clk_put()
when aborting after the clock has been enabled. The success path keeps
the slow clock enabled for the lifetime of the system timer and is left
untouched.

Fixes: adbaf5254152 ("clocksource/drivers/atmel-st: Convert init function to return error")
Cc: stable at vger.kernel.org
Signed-off-by: Wentao Liang <vulab at iscas.ac.cn>
---
 drivers/clocksource/timer-atmel-st.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-atmel-st.c b/drivers/clocksource/timer-atmel-st.c
index 73e8aee445da..e333916f8236 100644
--- a/drivers/clocksource/timer-atmel-st.c
+++ b/drivers/clocksource/timer-atmel-st.c
@@ -222,12 +222,15 @@ static int __init atmel_st_timer_init(struct device_node *node)
 	ret = clk_prepare_enable(sclk);
 	if (ret) {
 		pr_err("Could not enable slow clock\n");
+		clk_put(sclk);
 		return ret;
 	}
 
 	sclk_rate = clk_get_rate(sclk);
 	if (!sclk_rate) {
 		pr_err("Invalid slow clock rate\n");
+		clk_disable_unprepare(sclk);
+		clk_put(sclk);
 		return -EINVAL;
 	}
 	timer_latch = (sclk_rate + HZ / 2) / HZ;
@@ -244,7 +247,14 @@ static int __init atmel_st_timer_init(struct device_node *node)
 					2, AT91_ST_ALMV);
 
 	/* register clocksource */
-	return clocksource_register_hz(&clk32k, sclk_rate);
+	ret = clocksource_register_hz(&clk32k, sclk_rate);
+	if (ret) {
+		clk_disable_unprepare(sclk);
+		clk_put(sclk);
+		return ret;
+	}
+
+	return 0;
 }
 TIMER_OF_DECLARE(atmel_st_timer, "atmel,at91rm9200-st",
 		       atmel_st_timer_init);
-- 
2.34.1