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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F1F0C433FE for ; Thu, 10 Nov 2022 20:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229520AbiKJUJs (ORCPT ); Thu, 10 Nov 2022 15:09:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54104 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229588AbiKJUJq (ORCPT ); Thu, 10 Nov 2022 15:09:46 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 067692F382; Thu, 10 Nov 2022 12:09:45 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AC829B821E3; Thu, 10 Nov 2022 20:09:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F2D0C433C1; Thu, 10 Nov 2022 20:09:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668110982; bh=pSFInq4N4Bpw1KNnil1myJW1oupVm04I6GvyJ1r4M90=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZcRPHU5APr+eHfnFXysOgIHlqisvwx7xeSA+5tA0lqSek+E48B4aV6SQAlcs0pCJA NnU/H79xbc/Gy1kZYW7sdTDbh90GhkkpROQBxNf0sk3MxSLrmqRmCoYEFEDbLaQNOd x9qfjievWDnXssIKGrd6SFbBhsvsL6po7k9DuNmOR5yi7UfRMbawI9lpLkFA49RcXg mvSwCqPn+ahcGthFzjbeA+Ax7Ag/8d63rulA8xBN2hgCdw9Ex7gYX9nLZVzX3/YziR c0NgmJW2jnOpPzXjaGSBQleiT6VqNJvBtfkaVRJCWlqkhCLw1BZRtgvjYGRjXxdHAT Wa/QORdRpcl6g== From: SeongJae Park To: Rong Tao Cc: sj@kernel.org, Rong Tao , Shuah Khan , damon@lists.linux.dev, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Yuanchu Xie Subject: Re: [PATCH] selftests/damon: Fix unnecessary compilation warnings Date: Thu, 10 Nov 2022 20:09:39 +0000 Message-Id: <20221110200939.101886-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Cc-ing Yuanchu Xie. Hi Rong, On Thu, 10 Nov 2022 21:34:18 +0800 Rong Tao wrote: > From: Rong Tao > > When testing overflow and overread, there is no need to keep unnecessary > compilation warnings, we should simply ignore them. > > How to reproduce the problem: > > $ make -C tools/testing/selftests/ > gcc huge_count_read_write.c -o /home/sd/Git/linux/tools/testing/selftests/damon/huge_count_read_write 'checkpatch.pl' complains: WARNING: use relative pathname instead of absolute in changelog text #20: gcc huge_count_read_write.c -o /home/sd/Git/linux/tools/testing/selftests/damon/huge_count_read_write Also, could we add four spaces indent for code snippet/command outputs like above? > huge_count_read_write.c: In function ‘write_read_with_huge_count’: > huge_count_read_write.c:23:9: warning: ‘write’ reading 4294967295 bytes from a region of size 1 [-Wstringop-overread] > 23 | write(filedesc, "", 0xfffffffful); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > In file included from huge_count_read_write.c:8: > /usr/include/unistd.h:378:16: note: in a call to function ‘write’ declared with attribute ‘access (read_only, 2, 3)’ > 378 | extern ssize_t write (int __fd, const void *__buf, size_t __n) __wur > | ^~~~~ > huge_count_read_write.c:25:15: warning: ‘read’ writing 4294967295 bytes into a region of size 25 overflows the destination [-Wstringop-overflow=] > 25 | ret = read(filedesc, buf, 0xfffffffful); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > huge_count_read_write.c:14:14: note: destination object ‘buf’ of size 25 > 14 | char buf[25]; > | ^~~ > In file included from huge_count_read_write.c:8: > /usr/include/unistd.h:371:16: note: in a call to function ‘read’ declared with attribute ‘access (write_only, 2, 3)’ > 371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur > | ^~~~ > > Signed-off-by: Rong Tao > --- > tools/testing/selftests/damon/huge_count_read_write.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/tools/testing/selftests/damon/huge_count_read_write.c b/tools/testing/selftests/damon/huge_count_read_write.c > index ad7a6b4cf338..8fbe276870e7 100644 > --- a/tools/testing/selftests/damon/huge_count_read_write.c > +++ b/tools/testing/selftests/damon/huge_count_read_write.c > @@ -8,6 +8,11 @@ > #include > #include > > +#pragma GCC diagnostic push > +/* Ignore read(2) overflow and write(2) overread compile warnings */ > +#pragma GCC diagnostic ignored "-Wstringop-overread" > +#pragma GCC diagnostic ignored "-Wstringop-overflow" > + Thank you for sending this patch! However, there was a similar patch from Yuanchu[1], and this causes another warning for old gcc[2] that I use (9.4.0), like below. gcc -Wno-stringop-overread -Wno-stringop-overflow huge_count_read_write.c -o /home/sjpark/linux/tools/testing/selftests/damon/huge_count_read_write huge_count_read_write.c:13:32: warning: unknown option after ‘#pragma GCC diagnostic’ kind [-Wpragmas] 13 | #pragma GCC diagnostic ignored "-Wstringop-overread" | ^~~~~~~~~~~~~~~~~~~~~ cc1: warning: unrecognized command line option ‘-Wno-stringop-overread’ As mentioned as a reply to Yuanchu's patch, I'd slightly prefer making it silent for both new and old compilers than this approach, but no strong opinion from my side. Yuanchu and Shuah, do you have some opinion? [1] https://lore.kernel.org/lkml/CAJj2-QE4ee=N9wYXVQc6gyZYC3zgAsWVwWJ7DMaS2B9q2WqBHw@mail.gmail.com/ [2] https://lore.kernel.org/lkml/20220504184537.130085-1-sj@kernel.org/ [3] https://lore.kernel.org/lkml/20220517160417.1096-1-sj@kernel.org/ Thanks, SJ > void write_read_with_huge_count(char *file) > { > int filedesc = open(file, O_RDWR); > @@ -27,6 +32,8 @@ void write_read_with_huge_count(char *file) > close(filedesc); > } > > +#pragma GCC diagnostic pop > + > int main(int argc, char *argv[]) > { > if (argc != 2) { > -- > 2.31.1 > >