From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B15C7C35671 for ; Sun, 23 Feb 2020 10:02:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78018206ED for ; Sun, 23 Feb 2020 10:02:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kroah.com header.i=@kroah.com header.b="d1Mv/VgA"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="2FYG1jTa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726308AbgBWKCO (ORCPT ); Sun, 23 Feb 2020 05:02:14 -0500 Received: from wout4-smtp.messagingengine.com ([64.147.123.20]:43343 "EHLO wout4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725980AbgBWKCO (ORCPT ); Sun, 23 Feb 2020 05:02:14 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id B138D700; Sun, 23 Feb 2020 05:02:13 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Sun, 23 Feb 2020 05:02:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm3; bh=VWANkl3fWfXKI6vN6qGIPsZvGk/ Vwk+Eb8RLxQe/h3g=; b=d1Mv/VgAK9Jt/x5ycw55sEzfzvOuGd3G4R385jp5k5q al2RxgPDKQHcaLRuo/1N8fAQ+FPAVpPcGS8Pt5yZ2LgVmnjHdq7/Erkmrebo0lrF FcuTPy/mEKIfrArEQA8wtNyls8Y6L6mBAxn9jR0vDJYE0huAdcPMRGQAlO2nBmGT jIlra19/PL3JxgFNm3PSr37zrvGMTbpqxfLUBkrW6Y5X53kaHgXyf9M50Nk/OAHw qPoj3OmPG33BR4m4T+K+PK9ZdNCpqs2Xx2qI0UTVNOZwJzmUaVYCfpV8vSqnmQGj 2gx+QT3uYvv7DhXy+36hbZZF4VsBI6d74VVfS6y2fRw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=VWANkl 3fWfXKI6vN6qGIPsZvGk/Vwk+Eb8RLxQe/h3g=; b=2FYG1jTaKmxMTIncO+dOtn 3wr3DPe1Rs+EVtVN7870KgKByIshgGsF0MohFKVHlFzoLLIMvXc8PrYrYxPGyjTB KlXAKO3fJetk75m2Jn6CD33g3xC7rE4EOOkrjiPO+qfCoSfVVVBvfdSBKG3bo8aS 1fgQbMRAxVjGr7AJV5WMwsSKwgkRG6eIxIOy/n6hVGkJFET76/q9WpgU4s2FWg+z 5EcqPXvRH/j3sntZmi6DhuAdfAo+m1FlAtbzjq2JhNOJC38R8rpcDiwdlxg60Nvx Afx9R64+9NXrJlqf0lksQwzAqtqSnadpsd7/2myK4r2Vm1kd+xl6NFLgLFpYCRPg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrkeekgdduudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepifhrvghgucfm jfcuoehgrhgvgheskhhrohgrhhdrtghomheqnecukfhppeelhedrudeguddrleejrdduke dtnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepghhr vghgsehkrhhorghhrdgtohhm X-ME-Proxy: Received: from localhost (95-141-97-180.as16211.net [95.141.97.180]) by mail.messagingengine.com (Postfix) with ESMTPA id BACF43060FCB; Sun, 23 Feb 2020 05:02:12 -0500 (EST) Date: Sun, 23 Feb 2020 11:02:11 +0100 From: Greg KH To: Michael Hanselmann Cc: Johan Hovold , linux-usb@vger.kernel.org Subject: Re: [PATCH] ch341: Replace memory allocations with stack storage Message-ID: <20200223100211.GC120495@kroah.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Feb 21, 2020 at 07:23:41PM +0000, Michael Hanselmann wrote: > Storing a memory pointer consumes 4 or 8 bytes, depending on the > architecture. The replaced buffers are 2 bytes, so this change not only > avoids the overhead of memory allocation, but it also saves a small > amount of stack storage. > > Signed-off-by: Michael Hanselmann > --- > drivers/usb/serial/ch341.c | 32 ++++++++------------------------ > 1 file changed, 8 insertions(+), 24 deletions(-) You should have gotten a runtime error with this change if you tested it. Did that not happen somehow? As Johan said, all USB data has to be dynamically allocated. thanks, greg k-h