Messages in this thread | | | Date | Mon, 25 Apr 2016 15:27:02 -0700 | From | Stephen Boyd <> | Subject | Re: [PATCH] clk: fix member type of struct clk_hw_onecell_data |
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On 04/25, Masahiro Yamada wrote: > We cannot assign any value to an array type variable. So, > > hw_data->hws = kcalloc(hw_data->num, sizeof(struct clk_hw *), > GFP_KERNEL); > > fails with "invalid use of flexible array member" error.
That's good. We don't want assignment to the hws member of this structure to happen from an allocation like kcalloc.
> > There are two ways to fix this issue. > > [1] Make it a double-pointer > struct clk_hw_onecell_data { > size_t num; > struct clk_hw **hws; > }; > > This works as struct clk_onecell_data does.
True we could go back to the old style with two allocations.
> > [2] Make it a zero-sized array > struct clk_hw_onecell_data { > size_t num; > struct clk_hw *hws[0]; > }; > > This allows one-shot memory allocation like this: > > hw_data = kmalloc(sizeof(*hw_data) + clk_num * sizeof(struct clk_hw *), > GFP_KERNEL); >
Good, that was possible before this patch wasn't it?
> This commit adopts [2] because it looks like Stephen's intention > (he moved hws[] to the bottom of struct clk_hw_onecell_data). > > Fixes: 0861e5b8cf80 ("clk: Add clk_hw OF clk providers") > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > ---
> > include/linux/clk-provider.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > index fd2ccd5..1850e25 100644 > --- a/include/linux/clk-provider.h > +++ b/include/linux/clk-provider.h > @@ -769,7 +769,7 @@ struct clk_onecell_data { > > struct clk_hw_onecell_data { > size_t num; > - struct clk_hw *hws[]; > + struct clk_hw *hws[0];
I'm totally lost now. Isn't a flex array with [] or with [0] the same? The latter being a GCC extension while the former being a C99 standard?
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