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 df89cbfc1bd016e10c1cf3922cdb20175e870160..dcbe05616090de6d5a830cc8a5950fb282820eee 100644 (file)
--- 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);