From: Pawel Moll <pawel.moll@arm.com>
Date: Fri, 8 Jun 2012 13:04:06 +0000 (+0100)
Subject: clk: Check parent for NULL in clk_change_rate
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=bf47b4fd8f9f81cd5ce40e1945c6334d088226d1;p=sagit-ice-cold%2Fkernel_xiaomi_msm8998.git

clk: Check parent for NULL in clk_change_rate

clk_change_rate() is accessing parent's rate without checking
if the parent exists at all. In case of root clocks this will
cause NULL pointer dereference.

This patch follows what clk_calc_new_rates() does in such
situation.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Cc: stable@kernel.org
---

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index df89cbfc1bd0..dcbe05616090 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -850,18 +850,21 @@ static void clk_change_rate(struct clk *clk)
 {
 	struct clk *child;
 	unsigned long old_rate;
+	unsigned long best_parent_rate = 0;
 	struct hlist_node *tmp;
 
 	old_rate = clk->rate;
 
+	if (clk->parent)
+		best_parent_rate = clk->parent->rate;
+
 	if (clk->ops->set_rate)
-		clk->ops->set_rate(clk->hw, clk->new_rate, clk->parent->rate);
+		clk->ops->set_rate(clk->hw, clk->new_rate, best_parent_rate);
 
 	if (clk->ops->recalc_rate)
-		clk->rate = clk->ops->recalc_rate(clk->hw,
-				clk->parent->rate);
+		clk->rate = clk->ops->recalc_rate(clk->hw, best_parent_rate);
 	else
-		clk->rate = clk->parent->rate;
+		clk->rate = best_parent_rate;
 
 	if (clk->notifier_count && old_rate != clk->rate)
 		__clk_notify(clk, POST_RATE_CHANGE, old_rate, clk->rate);