On Thu, Mar 26, 2015 at 02:22:26PM +0000, Russell King - ARM Linux wrote:
> On Thu, Mar 26, 2015 at 07:13:38PM +0800, Leo Yan wrote:
> > +static unsigned long hisi_stub_clk_recalc_rate(struct clk_hw *hw,
> > + unsigned long parent_rate)
> > +{
> ...
> > + BUG_ON(!stub_clk->lock);
> ...
>
> > +static int hisi_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate)
> > +{
> ...
> > + BUG_ON(!stub_clk->lock);
> ...
>
> > +static long hisi_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long *parent_rate)
> > +{
> ...
> > + BUG_ON(!stub_clk->lock);
> ...
>
> > +static struct clk_ops hisi_stub_clk_ops = {
> > + .recalc_rate = hisi_stub_clk_recalc_rate,
> > + .round_rate = hisi_stub_clk_round_rate,
> > + .set_rate = hisi_stub_clk_set_rate,
> > +};
> ...
> > +static struct clk *_register_stub_clk(struct device *dev, unsigned int id,
> > + const char *name, const char *parent_name, unsigned long flags,
> > + spinlock_t *lock)
> > +{
> > + struct hisi_stub_clk *stub_clk;
> > + struct clk *clk;
> > + struct clk_init_data init;
> > +
> > + stub_clk = kzalloc(sizeof(*stub_clk), GFP_KERNEL);
> > + if (!stub_clk) {
> > + pr_err("%s: fail to alloc stub clk!\n", __func__);
> > + return ERR_PTR(-ENOMEM);
> > + }
> > +
> > + init.name = name;
> > + init.ops = &hisi_stub_clk_ops;
> > + init.parent_names = parent_name ? &parent_name : NULL;
> > + init.num_parents = parent_name ? 1 : 0;
> > + init.flags = flags;
> > +
> > + stub_clk->hw.init = &init;
> > + stub_clk->id = id;
> > + stub_clk->lock = lock;
>
> Under what scenario is it safe to call _register_stub_clk() with a NULL
> lock argument?
>
> If lock is NULL, then every function callable via the ops structure
> will bug.
>
> Rather than doing a test in each method function, do it in
> _register_stub_clk() - this means we aren't waiting for a NULL pointer
> deref when one of these method functions gets called.
Will fix to check lock pointer in the function _register_stub_clk().
Thanks,
Leo Yan
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