Messages in this thread |  | | From | Dong Aisheng <> | Date | Tue, 9 May 2017 20:14:35 +0800 | Subject | Re: [PATCH V2 1/3] clk: add clk_bulk_get accessories |
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Hi Geert,
On Mon, May 8, 2017 at 11:08 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote: > 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. >
I thought of it before and was wondering whether it's necessary to do it as i believe it may be wrong for drivers to reply on the clk_bulk API to do some some magic ordering to make things run because the API does not guarantee it.
But i do agree with you that it might be a common sense to release resource in inverse order, just harmless to do it! So i will make it in V3 if no objection from Maintainer later.
Thanks for your suggestion!
Regards Dong Aisheng
> 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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-clk" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
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