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authorMike Turquette <mturquette@linaro.org>2012-03-26 23:45:36 +0200
committerMike Turquette <mturquette@linaro.org>2012-04-25 01:37:37 +0200
commit7452b2191cd55fb3fd6ad65344466ddcdbe4676e (patch)
tree5ce68dcf470dd0de7bac7d354ea7be10e52467d5 /drivers/clk/clk.c
parentclk: core: remove dead code paths (diff)
downloadlinux-7452b2191cd55fb3fd6ad65344466ddcdbe4676e.tar.xz
linux-7452b2191cd55fb3fd6ad65344466ddcdbe4676e.zip
clk: core: clk_calc_new_rates handles NULL parents
It is possible to call clk_set_rate on a clock with a NULL parent. One such example is an adjustable-rate root clock. Ensure that clk_calc_new_rates does not dereference parent without checking first and also handle the corner cases gracefully. Reported-by: Rajendra Nayak <rnayak@ti.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/clk.c')
-rw-r--r--drivers/clk/clk.c29
1 files changed, 21 insertions, 8 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 4daacf5783aa..d83a9e09e1bf 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -763,25 +763,38 @@ static void clk_calc_subtree(struct clk *clk, unsigned long new_rate)
static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
{
struct clk *top = clk;
- unsigned long best_parent_rate = clk->parent->rate;
+ unsigned long best_parent_rate;
unsigned long new_rate;
- if (!clk->ops->round_rate && !(clk->flags & CLK_SET_RATE_PARENT)) {
- clk->new_rate = clk->rate;
+ /* sanity */
+ if (IS_ERR_OR_NULL(clk))
+ return NULL;
+
+ /* never propagate up to the parent */
+ if (!(clk->flags & CLK_SET_RATE_PARENT)) {
+ if (!clk->ops->round_rate) {
+ clk->new_rate = clk->rate;
+ return NULL;
+ } else {
+ new_rate = clk->ops->round_rate(clk->hw, rate, NULL);
+ goto out;
+ }
+ }
+
+ /* need clk->parent from here on out */
+ if (!clk->parent) {
+ pr_debug("%s: %s has NULL parent\n", __func__, clk->name);
return NULL;
}
- if (!clk->ops->round_rate && (clk->flags & CLK_SET_RATE_PARENT)) {
+ if (!clk->ops->round_rate) {
top = clk_calc_new_rates(clk->parent, rate);
new_rate = clk->new_rate = clk->parent->new_rate;
goto out;
}
- if (clk->flags & CLK_SET_RATE_PARENT)
- new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
- else
- new_rate = clk->ops->round_rate(clk->hw, rate, NULL);
+ new_rate = clk->ops->round_rate(clk->hw, rate, &best_parent_rate);
if (best_parent_rate != clk->parent->rate) {
top = clk_calc_new_rates(clk->parent, best_parent_rate);