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SubjectRe: [PATCH V2 1/3] clk: add clk_bulk_get accessories
Hi Dong,

On Mon, May 8, 2017 at 4:03 PM, Dong Aisheng <aisheng.dong@nxp.com> wrote:
> --- /dev/null
> +++ b/drivers/clk/clk-bulk.c
> @@ -0,0 +1,165 @@

> +int __must_check clk_bulk_get(struct device *dev, int num_clks,
> + struct clk_bulk_data *clks)
> +{
> + int ret;
> + int i;
> +
> + for (i = 0; i < num_clks; i++)
> + clks[i].clk = NULL;
> +
> + for (i = 0; i < num_clks; i++) {
> + clks[i].clk = clk_get(dev, clks[i].id);
> + if (IS_ERR(clks[i].clk)) {
> + ret = PTR_ERR(clks[i].clk);
> + dev_err(dev, "Failed to get clk '%s': %d\n",
> + clks[i].id, ret);
> + clks[i].clk = NULL;
> + goto err;
> + }
> + }
> +
> + return 0;
> +
> +err:
> + while (--i >= 0)
> + clk_put(clks[i].clk);

These are released in inverse order, which is good.

> +
> + return ret;
> +}
> +EXPORT_SYMBOL(clk_bulk_get);
> +
> +void clk_bulk_put(int num_clks, struct clk_bulk_data *clks)
> +{
> + int i;
> +
> + for (i = 0; i < num_clks; i++) {
> + clk_put(clks[i].clk);
> + clks[i].clk = NULL;

These aren't.

Typically resources are released in the inverse order. Not doing so may
cause subtle issues.

I can't come up with an example. but I'm quite sure the real world will find
one soon ;-)

The same is true for enable vs. disable, and prepare vs. unprepare.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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