From patchwork Mon Nov 2 15:20:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 11874209 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4879E139F for ; Mon, 2 Nov 2020 15:22:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2712122226 for ; Mon, 2 Nov 2020 15:22:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.b="hf6tvqnc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726472AbgKBPUq (ORCPT ); Mon, 2 Nov 2020 10:20:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726483AbgKBPUp (ORCPT ); Mon, 2 Nov 2020 10:20:45 -0500 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE738C061A49 for ; Mon, 2 Nov 2020 07:20:44 -0800 (PST) Received: by mail-wm1-x343.google.com with SMTP id k18so9866245wmj.5 for ; Mon, 02 Nov 2020 07:20:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=//ohTnlCNdzVCN7+X/oV4S8f/hxX7VdQ1OV3L6uwfhQ=; b=hf6tvqncwp3fkOIckHP3XNhZspBIs+DJCE72k4fKwWNNEV8tVYATPrk61RVN2LLtoy wyuT8kZJhciWHJYnIywhLp+tPKS38UhRZoDdJRNvydyfnF4jPWOOLNFaCIa5fWpPbqiE CPEcfMQCT8yeENUO+TRhPv8NZwnqBa/5qBgOFPacWV7BhHFuUJ5ASnX9vmHxuqU/2Ygy yl+QCczTs9fSAAWT/g0PiS+PxK7jWNW2R3D8R0j5FcPe+c2M0+55tW8i3tKhxnOrTffM d3zN4lSBg/UxZjb51Fwl4foaEs43EhxOe1ue2FxQvf65j62JS7V+E/ior/FALPI70AY8 3BnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=//ohTnlCNdzVCN7+X/oV4S8f/hxX7VdQ1OV3L6uwfhQ=; b=dtN0T4g6G9JMj60ClTU0KvubTg6YRmS6QBLBWzlA8VGc7ivyDTtfAcxYJTOA8enRn7 FippwVl8lWLeoqi12mj+Ab2+TWBpspxlImpSlchapQim6L0YVVzzz3s0e02VvkAKe3bg MJHongRTRYhh/lBkHAb+c2Tj3CveDehg3+5JS+gDeRd+tENnx+ci88o7lqEEx3oe8xgN e6K6SktLolGDfATAkldCZ8LkkchkYnlerkwp2fQs6/rAda823tv0cuAYTlV869oBzegA kICxFZiJ2SzS0w04B4t94x8rbqtUykACGpGGrqs2kqqrvdDykoMDWd4qO1IOpfDHwa0U vVkw== X-Gm-Message-State: AOAM532m6IYh144HVaow0FKLWvj/394lY5sdxA/txK46OUYPWeUvcnun WtvcW735i6EW3CpMZ+A0PLdOpw== X-Google-Smtp-Source: ABdhPJxGlAsjxjuqTsCnImH4txzUDEh+1CeV9f1Ji5E5b7hmF0/rUwH1lj/uHarBz/RRB7bv+TJwGA== X-Received: by 2002:a7b:cf25:: with SMTP id m5mr18034156wmg.124.1604330443460; Mon, 02 Nov 2020 07:20:43 -0800 (PST) Received: from debian-brgl.home (amarseille-656-1-4-167.w90-8.abo.wanadoo.fr. [90.8.158.167]) by smtp.gmail.com with ESMTPSA id b18sm15138014wmj.41.2020.11.02.07.20.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2020 07:20:42 -0800 (PST) From: Bartosz Golaszewski To: Andy Shevchenko , Sumit Semwal , Gustavo Padovan , =?utf-8?q?Christian_K=C3=B6nig?= , Mauro Carvalho Chehab , Borislav Petkov , Tony Luck , James Morse , Robert Richter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Alexander Shishkin , Linus Walleij , "Michael S . Tsirkin" , Jason Wang , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Jaroslav Kysela , Takashi Iwai Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-gpio@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-mm@kvack.org, alsa-devel@alsa-project.org, Bartosz Golaszewski , Vlastimil Babka Subject: [PATCH v2 1/8] mm: slab: provide krealloc_array() Date: Mon, 2 Nov 2020 16:20:30 +0100 Message-Id: <20201102152037.963-2-brgl@bgdev.pl> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201102152037.963-1-brgl@bgdev.pl> References: <20201102152037.963-1-brgl@bgdev.pl> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org From: Bartosz Golaszewski When allocating an array of elements, users should check for multiplication overflow or preferably use one of the provided helpers like: kmalloc_array(). There's no krealloc_array() counterpart but there are many users who use regular krealloc() to reallocate arrays. Let's provide an actual krealloc_array() implementation. While at it: add some documentation regarding krealloc. Signed-off-by: Bartosz Golaszewski Acked-by: Vlastimil Babka --- Documentation/core-api/memory-allocation.rst | 4 ++++ include/linux/slab.h | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+) diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst index 4446a1ac36cc..6dc38b40439a 100644 --- a/Documentation/core-api/memory-allocation.rst +++ b/Documentation/core-api/memory-allocation.rst @@ -147,6 +147,10 @@ The address of a chunk allocated with `kmalloc` is aligned to at least ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of two, the alignment is also guaranteed to be at least the respective size. +Chunks allocated with `kmalloc` can be resized with `krealloc`. Similarly +to `kmalloc_array`: a helper for resising arrays is provided in the form of +`krealloc_array`. + For large allocations you can use vmalloc() and vzalloc(), or directly request pages from the page allocator. The memory allocated by `vmalloc` and related functions is not physically contiguous. diff --git a/include/linux/slab.h b/include/linux/slab.h index dd6897f62010..be4ba5867ac5 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -592,6 +592,24 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags) return __kmalloc(bytes, flags); } +/** + * krealloc_array - reallocate memory for an array. + * @p: pointer to the memory chunk to reallocate + * @new_n: new number of elements to alloc + * @new_size: new size of a single member of the array + * @flags: the type of memory to allocate (see kmalloc) + */ +static __must_check inline void * +krealloc_array(void *p, size_t new_n, size_t new_size, gfp_t flags) +{ + size_t bytes; + + if (unlikely(check_mul_overflow(new_n, new_size, &bytes))) + return NULL; + + return krealloc(p, bytes, flags); +} + /** * kcalloc - allocate memory for an array. The memory is set to zero. * @n: number of elements.