From: Linus Torvalds <torvalds@linuxfoundation.org>
To: David Laight <David.Laight@aculab.com>
Cc: Arnd Bergmann <arnd@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Christoph Hellwig <hch@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Dan Carpenter <dan.carpenter@linaro.org>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
"pedro.falcato@gmail.com" <pedro.falcato@gmail.com>,
Mateusz Guzik <mjguzik@gmail.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 4/7] minmax: Simplify signedness check
Date: Thu, 25 Jul 2024 10:02:45 -0700 [thread overview]
Message-ID: <CAHk-=whLcr11D28vu2NotZYn3GNH6BCTK57Zw4d4v7eut39z=g@mail.gmail.com> (raw)
In-Reply-To: <5a129d04e0b84b48ba6c5189a047ac8f@AcuMS.aculab.com>
On Thu, 25 Jul 2024 at 02:01, David Laight <David.Laight@aculab.com> wrote:
>
> The condition is '>= 0' so it doesn't matter if it is '1' or '0'.
Yes, but that's because the whole conditional is so inexplicably complex.
But the explanation is:
> That gives a 'comparison of unsigned type against 0 is always true' warning.
> (The compiler generates that for code in the unused branches of both
> __builtin_choose_expr() and _Generic().)
> Moving the comparison to the outer level stops all such compiler warnings.
Christ. This whole series is a nightmare of "add complexity to deal
with stupid issues".
But the kernel test robot clearly found even more issues.
I think we need to just go back to the old code. It was stupid and
limited and caused us to have to be more careful about types than was
strictly necessary.
But it was also about a million times simpler, and didn't cause build
time regressions.
Linus
next prev parent reply other threads:[~2024-07-25 17:03 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-24 14:26 [PATCH 0/7] minmax: reduce compilation time David Laight
2024-07-24 14:28 ` [PATCH 1/7] minmax: Put all the clamp() definitions together David Laight
2024-07-24 14:29 ` [PATCH 2/7] minmax: Use _Static_assert() instead of static_assert() David Laight
2024-07-24 14:29 ` [PATCH 3/7] compiler.h: Add __if_constexpr(expr, if_const, if_not_const) David Laight
2024-07-24 17:32 ` Arnd Bergmann
2024-07-25 9:12 ` David Laight
2024-07-24 19:48 ` Linus Torvalds
2024-07-25 8:45 ` David Laight
2024-07-24 14:30 ` [PATCH 4/7] minmax: Simplify signedness check David Laight
2024-07-24 16:48 ` Arnd Bergmann
2024-07-24 20:02 ` Linus Torvalds
2024-07-25 9:00 ` David Laight
2024-07-25 17:02 ` Linus Torvalds [this message]
2024-07-26 9:43 ` Lorenzo Stoakes
2024-07-26 12:57 ` David Laight
2024-07-26 13:27 ` Lorenzo Stoakes
2024-07-25 13:24 ` kernel test robot
2024-07-25 16:39 ` David Laight
2024-07-24 14:31 ` [PATCH 5/7] minmax: Factor out the zero-extension logic from umin/umax David Laight
2024-07-24 14:32 ` [PATCH 6/7] minmax: Optimise _Static_assert() check in clamp() David Laight
2024-07-24 14:33 ` [PATCH 7/7] minmax: minmax: Add __types_ok3() and optimise defines with 3 arguments David Laight
2024-07-24 17:03 ` Arnd Bergmann
2024-07-25 9:07 ` David Laight
2024-07-24 19:34 ` [PATCH 0/7] minmax: reduce compilation time Lorenzo Stoakes
2024-07-24 19:52 ` Linus Torvalds
2024-07-26 18:12 ` Lorenzo Stoakes
2024-07-26 18:24 ` Linus Torvalds
2024-07-26 18:56 ` Lorenzo Stoakes
2024-07-26 19:21 ` Lorenzo Stoakes
2024-07-26 21:36 ` Linus Torvalds
2024-07-26 21:46 ` Jens Axboe
2024-07-26 22:48 ` Linus Torvalds
2024-07-27 15:30 ` Jens Axboe
2024-07-27 15:38 ` Jens Axboe
2024-07-27 16:31 ` Lorenzo Stoakes
2024-07-27 16:36 ` Jens Axboe
2024-07-27 16:41 ` Lorenzo Stoakes
2024-07-27 16:52 ` Jens Axboe
2024-07-27 16:56 ` Lorenzo Stoakes
2024-07-28 11:32 ` David Laight
2024-07-27 4:13 ` Linus Torvalds
2024-07-27 4:14 ` Linus Torvalds
2024-07-27 8:08 ` David Laight
2024-07-27 18:58 ` Lorenzo Stoakes
2024-07-27 19:21 ` Linus Torvalds
2024-07-28 11:17 ` David Laight
2024-07-28 13:07 ` Lorenzo Stoakes
2024-07-27 17:33 ` Matthew Wilcox
2024-07-27 18:16 ` Linus Torvalds
2024-07-27 8:07 ` Lorenzo Stoakes
2024-07-27 16:26 ` Linus Torvalds
2024-07-27 18:44 ` Lorenzo Stoakes
2024-07-30 4:10 ` Linus Torvalds
2024-07-30 10:36 ` Arnd Bergmann
2024-07-28 17:57 ` Geert Uytterhoeven
2024-07-28 18:43 ` Lorenzo Stoakes
2024-07-26 21:32 ` David Laight
2024-07-26 21:38 ` Linus Torvalds
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