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 picard.linux.it (picard.linux.it [213.254.12.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EA5A5C02194 for ; Thu, 6 Feb 2025 13:23:19 +0000 (UTC) Received: from picard.linux.it (localhost [IPv6:::1]) by picard.linux.it (Postfix) with ESMTP id 605CA3C9282 for ; Thu, 6 Feb 2025 14:23:18 +0100 (CET) Received: from in-2.smtp.seeweb.it (in-2.smtp.seeweb.it [217.194.8.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1)) (No client certificate requested) by picard.linux.it (Postfix) with ESMTPS id 9C5E93C04A5 for ; Thu, 6 Feb 2025 14:23:02 +0100 (CET) Authentication-Results: in-2.smtp.seeweb.it; spf=pass (sender SPF authorized) smtp.mailfrom=suse.cz (client-ip=2a07:de40:b251:101:10:150:64:1; helo=smtp-out1.suse.de; envelope-from=chrubis@suse.cz; receiver=lists.linux.it) Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2a07:de40:b251:101:10:150:64:1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by in-2.smtp.seeweb.it (Postfix) with ESMTPS id DAB9D651791 for ; Thu, 6 Feb 2025 14:23:01 +0100 (CET) Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 36AC421164; Thu, 6 Feb 2025 13:23:00 +0000 (UTC) Authentication-Results: smtp-out1.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 24D9013694; Thu, 6 Feb 2025 13:23:00 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id fPvwB7S3pGc9EAAAD6G6ig (envelope-from ); Thu, 06 Feb 2025 13:23:00 +0000 Date: Thu, 6 Feb 2025 14:22:57 +0100 From: Cyril Hrubis To: Jan Stancek Message-ID: References: <700f4d3bc73f0deebe7fe0e41305d365135c53eb.1738835278.git.jstancek@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[] X-Rspamd-Queue-Id: 36AC421164 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Virus-Scanned: clamav-milter 1.0.3 at in-2.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH] syscalls/mallinfo02: introduce LTP_VAR_USED to avoid optimization X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hi! > > > gcc 15 is a bit more clever and noticed that 'buf' isn't used > > > for anything so it optimized it out, including call to malloc. > > > So, there's also no mmap() call behind it and test fails, > > > because nothing was allocated. > > > > Huh, that sounds like the optimizations are getting more and more evil > > over the time. > > Also see the next patch for bpf. Sigh... > > > Introduce LTP_VAR_USED macro, that makes compiler aware of the > > > variable and doesn't optimize it out. > > > > > > Signed-off-by: Jan Stancek > > > --- > > > include/tst_common.h | 2 ++ > > > testcases/kernel/syscalls/mallinfo2/mallinfo2_01.c | 2 +- > > > 2 files changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/include/tst_common.h b/include/tst_common.h > > > index b14bbae04077..3de826acd0ec 100644 > > > --- a/include/tst_common.h > > > +++ b/include/tst_common.h > > > @@ -13,6 +13,8 @@ > > > #define LTP_ATTRIBUTE_UNUSED __attribute__((unused)) > > > #define LTP_ATTRIBUTE_UNUSED_RESULT __attribute__((warn_unused_result)) > > > > > > +#define LTP_VAR_USED(p) asm volatile("" :: "m"(p)); p > > > > Shouldn't __attribute__((used)) suffice? > > It's ignored for local variables. It does work for global ones. Maybe mention that in the commit description... Reviewed-by: Cyril Hrubis -- Cyril Hrubis chrubis@suse.cz -- Mailing list info: https://lists.linux.it/listinfo/ltp