[PATCH v14 02/18] bitfield: Add less-checking __FIELD_{GET,PREP}()

[Mikhail Kshevetskiy]

On 7/3/26 14:07, Mikhail Kshevetskiy wrote:
> On 7/2/26 16:59, Tom Rini wrote:
>> On Thu, Jul 02, 2026 at 11:53:05AM +0100, Simon Glass wrote:
>>> Hi Mikhail,
>>>
>>> On 2026-07-02T05:57:27, Mikhail Kshevetskiy
>>> <mikhail.kshevetskiy at iopsys.eu> wrote:
>>>> bitfield: Add less-checking __FIELD_{GET,PREP}()
>>>>
>>>> The BUILD_BUG_ON_MSG() check against '~0ull' works only with "unsigned
>>>> (long) long" _mask types.  For constant masks, that condition is usually
>>>> met, as GENMASK() yields an UL value.  The few places where the
>>>> constant mask is stored in an intermediate variable were fixed by
>>>> changing the variable type to u64 (see e.g. [1] and [2]).
>>>>
>>>> However, for non-constant masks, smaller unsigned types should be valid,
>>>> too, but currently lead to "result of comparison of constant
>>>> 18446744073709551615 with expression of type ... is always
>>>> false"-warnings with clang and W=1.
>>>>
>>>> Hence refactor the __BF_FIELD_CHECK() helper, and factor out
>>>> __FIELD_{GET,PREP}().  The later lack the single problematic check, but
>>>> are otherwise identical to FIELD_{GET,PREP}(), and are intended to be
>>>> used in the fully non-const variants later.
>>>>
>>>> [1] commit 5c667d5a5a3ec166 ("clk: sp7021: Adjust width of _m in
>>>>     HWM_FIELD_PREP()")
>>>> [...]
>>>>
>>>> include/linux/bitfield.h | 36 ++++++++++++++++++++++++++++--------
>>>>  1 file changed, 28 insertions(+), 8 deletions(-)
>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas at glider.be>
>>>> Link: https://git.kernel.org/torvalds/c/5c667d5a5a3ec166 [1]
>>>> Signed-off-by: Yury Norov (NVIDIA) <yury.norov at gmail.com>
>>>> Reviewed-by: David Lechner <dlechner at baylibre.com>
>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>
>>> Please can you add your own Signed-off-by at the end of the chain?
>>>
>>> It's a bit confusing that you seem to refer to Linux commit hashes in
>>> the commit. So maybe this should have a Cherry-picked-from: line
>>> indicating it came from Linux?
>> We don't use Cherry-picked-from (does anything?), we just mention what
>> the upstream commit was.
> There are several commits where something similar were used:
>
> 86a720aafce5b2 ("mtd: Introduce mtd_block_isreserved()")
> [scottwood: Cherry-picked from Linux 8471bb73ba10ed67]
> Signed-off-by: Scott Wood <scottwood at freescale.com>
>
> 88f95bbadda89b ("libfdt: Add fdt_next_subnode() to permit easy subnode
> iteration")
> (Cherry-picked from dtc commit 4e76ec79)
> Acked-by: Gerald Van Baren <vanbaren at cideas.com>
>
> c9fbe861a2fc1c ("arm64: dts: allwinner: h616: Add r_i2c pinctrl nodes")
> (cherry-picked from commit 1665557aa57c2140d014d68dfe1a1f92f9baac82)
> Reviewed-by: Andre Przywara <andre.przywara at arm.com>
>
> 13f3b04f61aa6a ("mtd: add mtd_ooblayout_xxx() helper functions")
> [Linux commit: 75eb2cec251fda33c9bb716ecc372819abb9278a]
> [masahiro: cherry-pick more code from
> adbbc3bc827eb1f43a932d783f09ba55c8ec8379]
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
>
> 1fb87de83dd6e7 ("mtd: nand: Support controllers with custom page")
> [Linux commit: 3371d663bb4579f1b2003a92162edd6d90edd089]
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
>
> and so on
I think we need some policy about cherry-picked commits. It should include:
* who should be an author of cherry-picked commits
* should or should not be original  Signed-off-by/Reviewed-by/Acked-by
be kept * how original commit should be referred