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clk: core: clk_calc_new_rates handles NULL parents

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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>
This commit is contained in:
Mike Turquette 2012-03-26 14:45:36 -07:00
parent 70d347e6cd
commit 7452b2191c
1 changed files with 21 additions and 8 deletions
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29
drivers/clk/clk.c
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@ -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);