From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jakub Kicinski <kubakici@wp.pl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] new byteorder primitives - ..._{replace,get}_bits()
Date: Wed, 13 Dec 2017 00:36:59 +0000 [thread overview]
Message-ID: <20171213003659.GA21978@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20171212155933.03c88eab@cakuba.netronome.com>
On Tue, Dec 12, 2017 at 03:59:33PM -0800, Jakub Kicinski wrote:
> > +static __always_inline __##type type##_replace_bits(__##type old, \
> > + base val, base mask) \
> > +{ \
> > + __##type m = to(mask); \
> > + if (__builtin_constant_p(val) && \
>
> Is the lack of a __builtin_constant_p(mask) test intentional? Sometimes
> the bitfield is a packed array and people may have a helper to which
> only the mask is passed as non-constant and the value is implied by the
> helper, thus constant.
If the mask in non-constant, we probably shouldn't be using that at all;
could you show a real-world example where that would be the case?
next prev parent reply other threads:[~2017-12-13 0:37 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-10 4:53 [RFC][PATCH] apparent big-endian bugs in dwc-xlgmac Al Viro
2017-12-11 4:33 ` Jie Deng
2017-12-11 5:05 ` Al Viro
2017-12-11 5:38 ` Al Viro
2017-12-11 6:46 ` Jie Deng
2017-12-11 15:54 ` [RFC][PATCH] new byteorder primitives - ..._{replace,get}_bits() Al Viro
2017-12-12 4:02 ` Jakub Kicinski
2017-12-12 6:20 ` Al Viro
2017-12-12 19:45 ` Al Viro
2017-12-12 20:04 ` Jakub Kicinski
2017-12-12 23:48 ` Al Viro
2017-12-12 23:59 ` Jakub Kicinski
2017-12-13 0:36 ` Al Viro [this message]
2017-12-13 1:04 ` Jakub Kicinski
2017-12-13 1:30 ` Al Viro
2017-12-13 1:35 ` Jakub Kicinski
2017-12-13 1:51 ` Al Viro
2017-12-13 2:44 ` Jakub Kicinski
2017-12-13 14:22 ` Al Viro
2017-12-13 17:45 ` Al Viro
2017-12-15 2:33 ` [RFC][PATCH] Add primitives for manipulating bitfields both in host- and fixed-endian Al Viro
2017-12-15 5:07 ` Jakub Kicinski
2017-12-15 5:34 ` Al Viro
2017-12-15 16:48 ` [RFC][PATCH v2] " Al Viro
2017-12-13 19:04 ` [RFC][PATCH] new byteorder primitives - ..._{replace,get}_bits() Jakub Kicinski
2017-12-11 6:18 ` [RFC][PATCH] apparent big-endian bugs in dwc-xlgmac Jie Deng
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