linux-kernel - [PATCH 2/2] drivers: sh: clk: Avoid crashes when passing NULL clocks

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Message-Id: <6575a9c69a211ac1cf454f9c76be54f7a5fae9fe.1453343708.git.horms+renesas@verge.net.au>
Date:	Thu, 21 Jan 2016 11:42:52 +0900
From:	Simon Horman <horms+renesas@...ge.net.au>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Magnus Damm <magnus.damm@...il.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Simon Horman <horms+renesas@...ge.net.au>
Subject: [PATCH 2/2] drivers: sh: clk: Avoid crashes when passing NULL clocks

From: Geert Uytterhoeven <geert+renesas@...der.be>

Several clock API functions handle NULL clocks when the Common Clock
Framework is used, while their legacy SH counterparts don't, and would
just crash when a NULL clock is passed.

Add NULL checks to clk_get_rate(), clk_set_rate(), clk_get_parent(), and
clk_round_rate(), to avoid different behavior in drivers shared between
legacy and CCF-based platforms.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
Signed-off-by: Simon Horman <horms+renesas@...ge.net.au>
---
 drivers/sh/clk/core.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/sh/clk/core.c b/drivers/sh/clk/core.c
index 6bf973bd9654..92863e3818e5 100644
--- a/drivers/sh/clk/core.c
+++ b/drivers/sh/clk/core.c
@@ -469,6 +469,9 @@ void clk_enable_init_clocks(void)
 
 unsigned long clk_get_rate(struct clk *clk)
 {
+	if (!clk)
+		return 0;
+
 	return clk->rate;
 }
 EXPORT_SYMBOL_GPL(clk_get_rate);
@@ -478,6 +481,9 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	int ret = -EOPNOTSUPP;
 	unsigned long flags;
 
+	if (!clk)
+		return 0;
+
 	spin_lock_irqsave(&clock_lock, flags);
 
 	if (likely(clk->ops && clk->ops->set_rate)) {
@@ -535,12 +541,18 @@ EXPORT_SYMBOL_GPL(clk_set_parent);
 
 struct clk *clk_get_parent(struct clk *clk)
 {
+	if (!clk)
+		return NULL;
+
 	return clk->parent;
 }
 EXPORT_SYMBOL_GPL(clk_get_parent);
 
 long clk_round_rate(struct clk *clk, unsigned long rate)
 {
+	if (!clk)
+		return 0;
+
 	if (likely(clk->ops && clk->ops->round_rate)) {
 		unsigned long flags, rounded;
 
-- 
2.1.4