From patchwork Mon Nov 9 11:06:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 11891013 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 BDAFC6A2 for ; Mon, 9 Nov 2020 11:07:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9346620731 for ; Mon, 9 Nov 2020 11:07:12 +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="aox5vh8y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729576AbgKILHI (ORCPT ); Mon, 9 Nov 2020 06:07:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729511AbgKILHE (ORCPT ); Mon, 9 Nov 2020 06:07:04 -0500 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27F8AC0613CF for ; Mon, 9 Nov 2020 03:07:04 -0800 (PST) Received: by mail-wr1-x444.google.com with SMTP id o15so383525wru.6 for ; Mon, 09 Nov 2020 03:07:04 -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=X2Rt2FzEDhfwvo5anIXOq/hUQeEl4/lxGNeKa+o6J0w=; b=aox5vh8ytYutbWVc26/liVn7Z8hEPu2nlIMQId7oA48asO+6m3jeTPz78Xi5tKvZ5M bwqHNNDNK70TD0NuDOZApqzQQQIxd7lpVAV+s12r5UTEgNsP0LLtTP/8WwzPWY/N5W3F Npda/QnMuuCjfODUnOM6c1KUKnZ4sERDBgsxwJiNxobq6BnhL/yQBZO223GeqTICPw9m vPcqcg/xsiMtQw2qzDEvFh+x8itNf6+A8g+1ljb0/aVhzJkxBCaUC9gPqB0T/1iCSeAD Up5ueADAnhN5fgjIVO2va7mHiOxvK3gevDqJSukErF5i8yrzIC+ShGo5F2g2sSe+Tv4s iVVA== 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=X2Rt2FzEDhfwvo5anIXOq/hUQeEl4/lxGNeKa+o6J0w=; b=CqSIC+ugHWLUKaiYTRb7j8F62Knw0sD93Ml7FTgwsYKWonw9zCOjv15U7fj3RsuDDh r9yyAhRtzfmtVRVtvrh12CqXAqbU5sL+0gBNX1N46u70LuPnmpGiSYNY1X9My3ulOuNM JW1YJ/jvsgMHt14Wws1n64dRxjHAWJt9HpOaqZOLaJEE3zD9bOpszxzbT7QIL7eY+i5Y H/xgjZ0PJUcJAx5tUz3HnCgd2IRRx68vcDJz3HsVyvpNckhBoehyQ8U1h/JqZTPfXwB3 dXXRPuejnss/dz5j64ETgbJZk127KS1zQDQqCNJAk9D2hb2WVw3xUNE0LqavQGRF4BDA N6QQ== X-Gm-Message-State: AOAM530+ephyA59c7+dRpFPKjkIEHwtWp3REW7U8cKMQttp/ze/iEsU8 LbN/gC7iVlH6MYzbwlkdFhYc5A== X-Google-Smtp-Source: ABdhPJz9QUvKGU969idAKC9U5b3ocmwgTjZ8J0vtC/TaPYMbRMpLHkJeyp4aCBCLAgcQ+m/LRxWMMA== X-Received: by 2002:adf:9066:: with SMTP id h93mr18252530wrh.166.1604920022928; Mon, 09 Nov 2020 03:07:02 -0800 (PST) Received: from localhost.localdomain (lfbn-nic-1-190-206.w2-15.abo.wanadoo.fr. [2.15.39.206]) by smtp.gmail.com with ESMTPSA id d3sm12815582wre.91.2020.11.09.03.07.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2020 03:07:02 -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 v3 2/9] mm: slab: provide krealloc_array() Date: Mon, 9 Nov 2020 12:06:47 +0100 Message-Id: <20201109110654.12547-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201109110654.12547-1-brgl@bgdev.pl> References: <20201109110654.12547-1-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..5954ddf6ee13 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 resizing 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.