So I'm not sure what your desired path for getting this upstream is. I
can take it, but I'm generally quite leery of taking coding-style
changes without some serious acks on them - nobody elected me as the
arbiter of proper coding style.
A nit below
Barry Song <21cnbao@xxxxxxxxx> writes:
> From: Barry Song <v-songbaohua@xxxxxxxx>
>
> Recent commit 77292bb8ca69c80 ("crypto: scomp - remove memcpy if
> sg_nents is 1 and pages are lowmem") leads to warnings on xtensa
> and loongarch,
> In file included from crypto/scompress.c:12:
> include/crypto/scatterwalk.h: In function 'scatterwalk_pagedone':
> include/crypto/scatterwalk.h:76:30: warning: variable 'page' set but not used [-Wunused-but-set-variable]
> 76 | struct page *page;
> | ^~~~
> crypto/scompress.c: In function 'scomp_acomp_comp_decomp':
>>> crypto/scompress.c:174:38: warning: unused variable 'dst_page' [-Wunused-variable]
> 174 | struct page *dst_page = sg_page(req->dst);
> |
>
> The reason is that flush_dcache_page() is implemented as a noop
> macro on these platforms as below,
>
> #define flush_dcache_page(page) do { } while (0)
>
> The driver code, for itself, seems be quite innocent and placing
> maybe_unused seems pointless,
>
> struct page *dst_page = sg_page(req->dst);
>
> for (i = 0; i < nr_pages; i++)
> flush_dcache_page(dst_page + i);
>
> And it should be independent of architectural implementation
> differences.
>
> Let's provide guidance on coding style for requesting parameter
> evaluation or proposing the migration to a static inline
> function.
>
> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
> Suggested-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
> Reviewed-by: Mark Brown <broonie@xxxxxxxxxx>
> Cc: Chris Zankel <chris@xxxxxxxxxx>
> Cc: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Cc: Andy Whitcroft <apw@xxxxxxxxxxxxx>
> Cc: Dwaipayan Ray <dwaipayanray1@xxxxxxxxx>
> Cc: Joe Perches <joe@xxxxxxxxxxx>
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx>
> Cc: Xining Xu <mac.xxn@xxxxxxxxxxx>
> ---
> Documentation/process/coding-style.rst | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst
> index 9c7cf7347394..791d333a57fd 100644
> --- a/Documentation/process/coding-style.rst
> +++ b/Documentation/process/coding-style.rst
> @@ -827,6 +827,22 @@ Macros with multiple statements should be enclosed in a do - while block:
> do_this(b, c); \
> } while (0)
>
> +Function-like macros with unused parameters should be replaced by static
> +inline functions to avoid the issue of unused variables:
> +
> +.. code-block:: c
I would just use the "::" notation here; the ..code-block:: just adds
noise IMO.
> + static inline void fun(struct foo *foo)
> + {
> + }
> +
> +For historical reasons, many files still use the cast to (void) to evaluate
> +parameters, but this method is not recommended:
> +
> +.. code-block:: c
> +
> + #define macrofun(foo) do { (void) (foo); } while (0)
> +
1) If you're putting in examples of something *not* to do, it's probably
better to also put in something like:
/* don't do this */
people don't always read closely.
2) Can we say *why* it's not recommended?
Thanks,
jon
