From: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>
To: "Pierre-Clément Tosi" <ptosi-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: devicetree-compiler-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Mostafa Saleh <smostafa-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH] libfdt: Fix fdt_appendprop_addrrange documentation
Date: Mon, 4 Sep 2023 15:31:01 +1000 [thread overview]
Message-ID: <ZPVrlffenIPXDxJb@zatzit> (raw)
In-Reply-To: <20230831123918.rf54emwkzgtcb7aw-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
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On Thu, Aug 31, 2023 at 01:39:18PM +0100, Pierre-Clément Tosi wrote:
> According to the documentation, the function should default to the very
> common property name <reg> when none is "specified". However, neither
> passing NULL (ends up calling strlen(NULL) and segfaults) nor ""
> (appends a property with an empty name) implements this behavior.
>
> Furthermore, the test case supposed to cover this default value actually
> passes the value to the function, somewhat defeating its own purpose:
>
> /* 2. default property name */
>
> // ...
>
> err = fdt_appendprop_addrrange(fdt, 0, offset, "reg", addr, size);
> if (err)
> FAIL("Failed to set \"reg\": %s", fdt_strerror(err));
> check_getprop_addrrange(fdt, 0, offset, "reg", 1);
>
> Finally, nothing in the implementation of the function seems to attempt
> to cover that use-case.
>
> As the feature can't ever have been used by clients and as the resulting
> reduced readability of the caller seems (IMO) to outweigh any potential
> benefit this API would bring, remove the erroneous documentation instead
> of trying to fix the function.
>
> Reported-by: Mostafa Saleh <smostafa-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Pierre-Clément Tosi <ptosi-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Nice catch, and an excellent commit message.
I don't recall this specifically, but my guess would be that an
original draft included that behaviour, but I nixed it during review,
but then both the submitted and I forgot to update the documentation
comments as well.
Merged.
> ---
> libfdt/libfdt.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index 2a4f32c..0677fea 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -2029,7 +2029,7 @@ static inline int fdt_appendprop_cell(void *fdt, int nodeoffset,
> * address and size) to the value of the named property in the given
> * node, or creates a new property with that value if it does not
> * already exist.
> - * If "name" is not specified, a default "reg" is used.
> + *
> * Cell sizes are determined by parent's #address-cells and #size-cells.
> *
> * This function may insert data into the blob, and will therefore
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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prev parent reply other threads:[~2023-09-04 5:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-31 12:39 [PATCH] libfdt: Fix fdt_appendprop_addrrange documentation Pierre-Clément Tosi
[not found] ` <20230831123918.rf54emwkzgtcb7aw-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2023-09-04 5:31 ` David Gibson [this message]
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