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Message-ID: <20250919101727.16152-12-farbere@amazon.com> Date: Fri, 19 Sep 2025 10:17:11 +0000 From: Eliav Farber <farbere@...zon.com> To: <linux@...linux.org.uk>, <jdike@...toit.com>, <richard@....at>, <anton.ivanov@...bridgegreys.com>, <dave.hansen@...ux.intel.com>, <luto@...nel.org>, <peterz@...radead.org>, <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>, <x86@...nel.org>, <hpa@...or.com>, <tony.luck@...el.com>, <qiuxu.zhuo@...el.com>, <mchehab@...nel.org>, <james.morse@....com>, <rric@...nel.org>, <harry.wentland@....com>, <sunpeng.li@....com>, <alexander.deucher@....com>, <christian.koenig@....com>, <airlied@...ux.ie>, <daniel@...ll.ch>, <evan.quan@....com>, <james.qian.wang@....com>, <liviu.dudau@....com>, <mihail.atanassov@....com>, <brian.starkey@....com>, <maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>, <tzimmermann@...e.de>, <robdclark@...il.com>, <sean@...rly.run>, <jdelvare@...e.com>, <linux@...ck-us.net>, <fery@...ress.com>, <dmitry.torokhov@...il.com>, <agk@...hat.com>, <snitzer@...hat.com>, <dm-devel@...hat.com>, <rajur@...lsio.com>, <davem@...emloft.net>, <kuba@...nel.org>, <peppe.cavallaro@...com>, <alexandre.torgue@...com>, <joabreu@...opsys.com>, <mcoquelin.stm32@...il.com>, <malattia@...ux.it>, <hdegoede@...hat.com>, <mgross@...ux.intel.com>, <intel-linux-scu@...el.com>, <artur.paszkiewicz@...el.com>, <jejb@...ux.ibm.com>, <martin.petersen@...cle.com>, <sakari.ailus@...ux.intel.com>, <gregkh@...uxfoundation.org>, <clm@...com>, <josef@...icpanda.com>, <dsterba@...e.com>, <jack@...e.com>, <tytso@....edu>, <adilger.kernel@...ger.ca>, <dushistov@...l.ru>, <luc.vanoostenryck@...il.com>, <rostedt@...dmis.org>, <pmladek@...e.com>, <sergey.senozhatsky@...il.com>, <andriy.shevchenko@...ux.intel.com>, <linux@...musvillemoes.dk>, <minchan@...nel.org>, <ngupta@...are.org>, <akpm@...ux-foundation.org>, <kuznet@....inr.ac.ru>, <yoshfuji@...ux-ipv6.org>, <pablo@...filter.org>, <kadlec@...filter.org>, <fw@...len.de>, <jmaloy@...hat.com>, <ying.xue@...driver.com>, <willy@...radead.org>, <farbere@...zon.com>, <sashal@...nel.org>, <ruanjinjie@...wei.com>, <David.Laight@...LAB.COM>, <herve.codina@...tlin.com>, <Jason@...c4.com>, <bvanassche@....org>, <keescook@...omium.org>, <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>, <linux-um@...ts.infradead.org>, <linux-edac@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>, <dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>, <freedreno@...ts.freedesktop.org>, <linux-hwmon@...r.kernel.org>, <linux-input@...r.kernel.org>, <linux-media@...r.kernel.org>, <netdev@...r.kernel.org>, <linux-stm32@...md-mailman.stormreply.com>, <platform-driver-x86@...r.kernel.org>, <linux-scsi@...r.kernel.org>, <linux-staging@...ts.linux.dev>, <linux-btrfs@...r.kernel.org>, <linux-ext4@...r.kernel.org>, <linux-sparse@...r.kernel.org>, <linux-mm@...ck.org>, <netfilter-devel@...r.kernel.org>, <coreteam@...filter.org>, <tipc-discussion@...ts.sourceforge.net>, <stable@...r.kernel.org> CC: <jonnyc@...zon.com>, Christoph Hellwig <hch@...radead.org>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: [PATCH 11/27 5.10.y] minmax: relax check to allow comparison between unsigned arguments and signed constants From: David Laight <David.Laight@...LAB.COM> [ Upstream commit 867046cc7027703f60a46339ffde91a1970f2901 ] Allow (for example) min(unsigned_var, 20). The opposite min(signed_var, 20u) is still errored. Since a comparison between signed and unsigned never makes the unsigned value negative it is only necessary to adjust the __types_ok() test. Link: https://lkml.kernel.org/r/633b64e2f39e46bb8234809c5595b8c7@AcuMS.aculab.com Signed-off-by: David Laight <david.laight@...lab.com> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com> Cc: Christoph Hellwig <hch@...radead.org> Cc: Jason A. Donenfeld <Jason@...c4.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Matthew Wilcox (Oracle) <willy@...radead.org> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Eliav Farber <farbere@...zon.com> --- include/linux/minmax.h | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/include/linux/minmax.h b/include/linux/minmax.h index 842c1db62ffe..2ec559284a9f 100644 --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -10,13 +10,18 @@ /* * min()/max()/clamp() macros must accomplish three things: * - * - avoid multiple evaluations of the arguments (so side-effects like + * - Avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. - * - perform signed v unsigned type-checking (to generate compile - * errors instead of nasty runtime surprises). - * - retain result as a constant expressions when called with only + * - Retain result as a constant expressions when called with only * constant expressions (to avoid tripping VLA warnings in stack * allocation usage). + * - Perform signed v unsigned type-checking (to generate compile + * errors instead of nasty runtime surprises). + * - Unsigned char/short are always promoted to signed int and can be + * compared against signed or unsigned arguments. + * - Unsigned arguments can be compared against non-negative signed constants. + * - Comparison of a signed argument against an unsigned constant fails + * even if the constant is below __INT_MAX__ and could be cast to int. */ #define __typecheck(x, y) \ (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) @@ -26,9 +31,14 @@ __builtin_choose_expr(__is_constexpr(is_signed_type(typeof(x))), \ is_signed_type(typeof(x)), 0) -#define __types_ok(x, y) \ - (__is_signed(x) == __is_signed(y) || \ - __is_signed((x) + 0) == __is_signed((y) + 0)) +/* True for a non-negative signed int constant */ +#define __is_noneg_int(x) \ + (__builtin_choose_expr(__is_constexpr(x) && __is_signed(x), x, -1) >= 0) + +#define __types_ok(x, y) \ + (__is_signed(x) == __is_signed(y) || \ + __is_signed((x) + 0) == __is_signed((y) + 0) || \ + __is_noneg_int(x) || __is_noneg_int(y)) #define __cmp_op_min < #define __cmp_op_max > -- 2.47.3
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