From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A4337253F1A; Fri, 17 Oct 2025 08:16:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760689016; cv=none; b=IFIbWR7C4Wy6DyyrgTjq2RVa7hwhUEh1BeNwYBRAkMx4I355wfFkG6U1ortLHCAKMGl3mzR6KgRxKe4QUOGW3q/+dgTyhu/7OIGJ2I5gj1qHxzuVpUe9BmbnqIITv5w4YvYP5UfjPpo+Zxi8tVoLfPsJn02vEMwRnkgwsNT9ILg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760689016; c=relaxed/simple; bh=/nupFfiBDTK8f3z19X5zBCAoNMhBKwg/9yA8JDj7YJ8=; h=Subject:To:Cc:From:Date:In-Reply-To:Message-ID:MIME-Version: Content-Type; b=stmVOiMLsQcifHsO8hvFMGjo1OjXSJ4Ri49akiPI9nU1tUNUBWq/+ug0QegOEmN+QmVIU6ZZchljvMbqU8vJG/D5GziYZjlflv39PLH6qc8UC1EwYzbwKEzV3dwOYHXLJZyLY+AZeT4rXdX1IqcfpprILNa/JCAYC8n30ZDprNw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ekUis2qS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ekUis2qS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8ECFBC19421; Fri, 17 Oct 2025 08:16:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1760689016; bh=/nupFfiBDTK8f3z19X5zBCAoNMhBKwg/9yA8JDj7YJ8=; h=Subject:To:Cc:From:Date:In-Reply-To:From; b=ekUis2qS/K43Wa3oMb6pzVrmzyh0OGl14tcBxht+kGV+lez/llzNd0s9mNO0RzixN Q75JOdhNNo5UNgwXRxdAmWUi1TmKQfgq+e5PzKWDXtyivWCST/OSYnWJkfXMnb/O0F bWFd3BTr2YRTDY2ZsyW9T5wO/yvIT9f9cT9MABvo= Subject: Patch "minmax.h: update some comments" has been added to the 5.15-stable tree To: David.Laight@ACULAB.COM,Jason@zx2c4.com,adilger.kernel@dilger.ca,agk@redhat.com,airlied@linux.ie,akpm@linux-foundation.org,amd-gfx@lists.freedesktop.org,andriy.shevchenko@linux.intel.com,anton.ivanov@cambridgegreys.com,arnd@kernel.org,axboe@kernel.dk,bp@alien8.de,clm@fb.com,coreteam@netfilter.org,dan.carpenter@linaro.org,daniel@ffwll.ch,dave.hansen@linux.intel.com,davem@davemloft.net,david.laight@aculab.com,dm-devel@redhat.com,dmitry.torokhov@gmail.com,dri-devel@lists.freedesktop.org,dsahern@kernel.org,dsterba@suse.com,dushistov@mail.ru,farbere@amazon.com,freedreno@lists.freedesktop.org,fw@strlen.de,gregkh@linuxfoundation.org,hch@infradead.org,hdegoede@redhat.com,herve.codina@bootlin.com,hpa@zytor.com,jack@suse.com,james.morse@arm.com,jdelvare@suse.com,jdike@addtoit.com,jejb@linux.ibm.com,jernej.skrabec@gmail.com,jmaloy@redhat.com,josef@toxicpanda.com,kadlec@netfilter.org,krzysztof.kozlowski@canonical.com,kuba@kernel.org,linus.walleij@linaro.org,linux-arm-kernel@lists.infradead.org,linux-mm@kvack.org,linux-staging@lists.linux.dev,linux-stm32@st-md-mailman.stormreply.com,linux-sunxi@lists.linux.dev,linux-um@lists.infradead.org,linux@rasmusvillemoes.dk,linux@roeck-us.net,lorenzo.stoakes@oracle.com,luc.vanoostenryck@gmail.com,luto@kernel.org,maarten.lankhorst@linux.intel.com,malattia@linux.it,martin.petersen@oracle.com,maz@kernel.org,mcoquelin.stm32@gmail.com,mgross@linux.intel.com,minchan@kernel.org,mingo@redhat.com,mjguzik@gmail.com,mripard@kernel.org,ngupta@vflare.org,pablo@netfilter.org,pedro.falcato@gmail.com,peterz@infradead.org,pmladek@suse.com,qiuxu.zhuo@intel.com,quic_akhilpo@quicinc.com,richard@nod.at,robdclark@gmail.com,rostedt@goodmis.org,rric@kernel.org,ruanjinjie@huawei.com,sakari.ailus@linux.intel.com,sashal@kernel.org,sean@poorly.run,senozhatsky@chromium.org,shuah@kernel.org,snitzer@redhat.com,tglx@linutronix.de,tipc-discussion@lists.sourceforge.net,tony.luck@intel.com,tytso@mit.edu,tzimmermann@suse.de,wens@csie.org,willy@infradead.org,x86@kernel.org,ying.xue@windriver.com,yoshfuji@linux-ipv6.org Cc: From: Date: Fri, 17 Oct 2025 10:16:20 +0200 In-Reply-To: <20251008152946.29285-15-farbere@amazon.com> Message-ID: <2025101720-splashed-matriarch-b59d@gregkh> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit X-stable: commit X-Patchwork-Hint: ignore This is a note to let you know that I've just added the patch titled minmax.h: update some comments to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: minmax.h-update-some-comments.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >From prvs=36971892a=farbere@amazon.com Wed Oct 8 17:34:21 2025 From: Eliav Farber Date: Wed, 8 Oct 2025 15:29:39 +0000 Subject: minmax.h: update some comments To: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Cc: Arnd Bergmann , Christoph Hellwig , Dan Carpenter , "Jason A. Donenfeld" , Jens Axboe , Lorenzo Stoakes , Mateusz Guzik , "Pedro Falcato" Message-ID: <20251008152946.29285-15-farbere@amazon.com> From: David Laight [ Upstream commit 10666e99204818ef45c702469488353b5bb09ec7 ] - Change three to several. - Remove the comment about retaining constant expressions, no longer true. - Realign to nearer 80 columns and break on major punctiation. - Add a leading comment to the block before __signed_type() and __is_nonneg() Otherwise the block explaining the cast is a bit 'floating'. Reword the rest of that comment to improve readability. Link: https://lkml.kernel.org/r/85b050c81c1d4076aeb91a6cded45fee@AcuMS.aculab.com Signed-off-by: David Laight Cc: Andy Shevchenko Cc: Arnd Bergmann Cc: Christoph Hellwig Cc: Dan Carpenter Cc: Jason A. Donenfeld Cc: Jens Axboe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox Cc: Pedro Falcato Signed-off-by: Andrew Morton Signed-off-by: Eliav Farber Signed-off-by: Greg Kroah-Hartman --- include/linux/minmax.h | 61 ++++++++++++++++++++++--------------------------- 1 file changed, 28 insertions(+), 33 deletions(-) --- a/include/linux/minmax.h +++ b/include/linux/minmax.h @@ -8,13 +8,10 @@ #include /* - * min()/max()/clamp() macros must accomplish three things: + * min()/max()/clamp() macros must accomplish several things: * * - Avoid multiple evaluations of the arguments (so side-effects like * "x++" happen only once) when non-constant. - * - 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 @@ -31,25 +28,23 @@ * bit #0 set if ok for unsigned comparisons * bit #1 set if ok for signed comparisons * - * In particular, statically non-negative signed integer - * expressions are ok for both. + * In particular, statically non-negative signed integer expressions + * are ok for both. * - * NOTE! Unsigned types smaller than 'int' are implicitly - * converted to 'int' in expressions, and are accepted for - * signed conversions for now. This is debatable. - * - * Note that 'x' is the original expression, and 'ux' is - * the unique variable that contains the value. - * - * We use 'ux' for pure type checking, and 'x' for when - * we need to look at the value (but without evaluating - * it for side effects! Careful to only ever evaluate it - * with sizeof() or __builtin_constant_p() etc). - * - * Pointers end up being checked by the normal C type - * rules at the actual comparison, and these expressions - * only need to be careful to not cause warnings for - * pointer use. + * NOTE! Unsigned types smaller than 'int' are implicitly converted to 'int' + * in expressions, and are accepted for signed conversions for now. + * This is debatable. + * + * Note that 'x' is the original expression, and 'ux' is the unique variable + * that contains the value. + * + * We use 'ux' for pure type checking, and 'x' for when we need to look at the + * value (but without evaluating it for side effects! + * Careful to only ever evaluate it with sizeof() or __builtin_constant_p() etc). + * + * Pointers end up being checked by the normal C type rules at the actual + * comparison, and these expressions only need to be careful to not cause + * warnings for pointer use. */ #define __signed_type_use(x, ux) (2 + __is_nonneg(x, ux)) #define __unsigned_type_use(x, ux) (1 + 2 * (sizeof(ux) < 4)) @@ -57,19 +52,19 @@ __signed_type_use(x, ux) : __unsigned_type_use(x, ux)) /* - * To avoid warnings about casting pointers to integers - * of different sizes, we need that special sign type. + * Check whether a signed value is always non-negative. * - * On 64-bit we can just always use 'long', since any - * integer or pointer type can just be cast to that. + * A cast is needed to avoid any warnings from values that aren't signed + * integer types (in which case the result doesn't matter). * - * This does not work for 128-bit signed integers since - * the cast would truncate them, but we do not use s128 - * types in the kernel (we do use 'u128', but they will - * be handled by the !is_signed_type() case). - * - * NOTE! The cast is there only to avoid any warnings - * from when values that aren't signed integer types. + * On 64-bit any integer or pointer type can safely be cast to 'long'. + * But on 32-bit we need to avoid warnings about casting pointers to integers + * of different sizes without truncating 64-bit values so 'long' or 'long long' + * must be used depending on the size of the value. + * + * This does not work for 128-bit signed integers since the cast would truncate + * them, but we do not use s128 types in the kernel (we do use 'u128', + * but they are handled by the !is_signed_type() case). */ #ifdef CONFIG_64BIT #define __signed_type(ux) long Patches currently in stable-queue which might be from farbere@amazon.com are queue-5.15/minmax-add-a-few-more-min_t-max_t-users.patch queue-5.15/minmax-improve-macro-expansion-and-type-checking.patch queue-5.15/minmax-fix-indentation-of-__cmp_once-and-__clamp_once.patch queue-5.15/minmax.h-simplify-the-variants-of-clamp.patch queue-5.15/minmax-add-in_range-macro.patch queue-5.15/minmax.h-move-all-the-clamp-definitions-after-the-min-max-ones.patch queue-5.15/minmax-don-t-use-max-in-situations-that-want-a-c-constant-expression.patch queue-5.15/minmax.h-remove-some-defines-that-are-only-expanded-once.patch queue-5.15/minmax.h-use-build_bug_on_msg-for-the-lo-hi-test-in-clamp.patch queue-5.15/minmax-simplify-min-max-clamp-implementation.patch queue-5.15/minmax-deduplicate-__unconst_integer_typeof.patch queue-5.15/minmax-simplify-and-clarify-min_t-max_t-implementation.patch queue-5.15/minmax.h-add-whitespace-around-operators-and-after-commas.patch queue-5.15/minmax-avoid-overly-complicated-constant-expressions-in-vm-code.patch queue-5.15/minmax-make-generic-min-and-max-macros-available-everywhere.patch queue-5.15/minmax-fix-up-min3-and-max3-too.patch queue-5.15/minmax.h-reduce-the-define-expansion-of-min-max-and-clamp.patch queue-5.15/minmax-introduce-min-max-_array.patch queue-5.15/minmax.h-update-some-comments.patch