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From: David Laight <David.Laight@ACULAB.COM>
To: 'Alex Elder' <elder@linaro.org>,
	"subashab@codeaurora.org" <subashab@codeaurora.org>,
	"stranche@codeaurora.org" <stranche@codeaurora.org>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kuba@kernel.org" <kuba@kernel.org>
Cc: "sharathv@codeaurora.org" <sharathv@codeaurora.org>,
	"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
	"evgreen@chromium.org" <evgreen@chromium.org>,
	"cpratapa@codeaurora.org" <cpratapa@codeaurora.org>,
	"elder@kernel.org" <elder@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"kernel test robot" <lkp@intel.com>
Subject: RE: [PATCH net-next v2 6/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum header
Date: Mon, 8 Mar 2021 14:10:46 +0000	[thread overview]
Message-ID: <8452678da3a647249780b60e857bb32a@AcuMS.aculab.com> (raw)
In-Reply-To: <cc8e3bb0-81f0-070b-5b70-342dc172a1a2@linaro.org>

...
> Sort of related, I have been meaning to eliminate the
> pointless __aligned(1) tags on rmnet structures defined
> in <linux/if_rmnet.h>.  It wouldn't hurt to use __packed,
> though I think they're all 4 or 8 bytes naturally anyway.
> Perhaps marking them __aligned(4) would help identify
> potential unaligned accesses?

Don't use __packed (etc) unless the data might be misaligned.
If the architecture doesn't support misaligned memory
accesses then the compiler has to generate code that
does byte accesses and shifts.

__aligned(4) is mostly useful for structures that have
to have an 8-byte field on a 4-byte boundary.
(As happens in the x86 compat32 code.)

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

      reply	other threads:[~2021-03-08 14:11 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-06  3:15 [PATCH net-next v2 0/6] net: qualcomm: rmnet: stop using C bit-fields Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 1/6] net: qualcomm: rmnet: mark trailer field endianness Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 2/6] net: qualcomm: rmnet: simplify some byte order logic Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 3/6] net: qualcomm: rmnet: kill RMNET_MAP_GET_*() accessor macros Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 4/6] net: qualcomm: rmnet: use field masks instead of C bit-fields Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 5/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum trailer Alex Elder
2021-03-08 10:13   ` David Laight
2021-03-08 13:39     ` Alex Elder
2021-03-08 13:53       ` David Laight
2021-03-08 14:19         ` Alex Elder
2021-03-06  3:15 ` [PATCH net-next v2 6/6] net: qualcomm: rmnet: don't use C bit-fields in rmnet checksum header Alex Elder
2021-03-08 10:18   ` David Laight
2021-03-08 13:59     ` Alex Elder
2021-03-08 14:10       ` David Laight [this message]

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