From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0189D23F37E; Fri, 28 Feb 2025 23:59:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740787148; cv=none; b=M6xoUsEIwU+JLug5UOTdZWg5XEJUuHypMUFlsk9AGIWIJpFQLpDNv4Lh5F8vMCkMOIpffKXtJB+vlH/QXW4D1yMBcY8C5Ic1bVMRMx7I7yRbXJ4fSjhguG5WpKOJVYtY9+0IWCvST8fWth90VSBPi6QRa4/kgEjUuJPf3kdRLyU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740787148; c=relaxed/simple; bh=/WRkCTtYXh1ybFkJl4MN82rEMEE7Dqv4CfKN/PIu86I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WdbdnkaZgbE3K35n5I49dYB7+UArWddNPL+fnIlprpQLIUns1cPAdDGWx9jSjrt35r5rU7FaxVxjn5qbrysu6fGYExSzQvyAWTF7YQITY27ORE3bjxohY7abZWgqDJQ7r4PW8fGERPIiS8OxD6qSL2G9/Rnu4xiDGQp7EXIGMMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eDCS2Rhg; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="eDCS2Rhg" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E19EFC4CED6; Fri, 28 Feb 2025 23:59:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740787147; bh=/WRkCTtYXh1ybFkJl4MN82rEMEE7Dqv4CfKN/PIu86I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eDCS2RhgJ3XeJ8PwYBssIw14ioLDPLOzgCLtMmdCB/92m8kx9w8Xp7CE3M4Eupfuj VKOWY/Ow6UH5d1+LhjbIfYE9i34Czsxav+qaG1ZQoE2pFApwgI0qx9jn0kuYEgh65f 82zvZkbSPPv6OEc1rMc6XuHQMkSrw3QQeIJLekaaAOwXHQmDWl25oJyuCFcUqi7qKQ D9nCvcLpu0i9lKiHSzg6+f1yo+FL8vhiKtJuVsELx1ZayO4iHc5fCGuoc23KvEuwLp lerDaBOk4jTCbct9GOtKbzOppoGw+K6wdIOCeFWJC4FSHxLwQOKdnvwu9vFrklrHLs 4xnA4cN4clrFw== Date: Fri, 28 Feb 2025 15:59:05 -0800 From: Namhyung Kim To: Charlie Jenkins Cc: Luca Ceresoli , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Andi Kleen , Thomas Petazzoni , Alexis =?utf-8?Q?Lothor=C3=A9?= , Arnaldo Carvalho de Melo , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf build: fix in-tree build Message-ID: References: <20250124-perf-fix-intree-build-v1-1-485dd7a855e4@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Hello, On Fri, Feb 28, 2025 at 02:08:24PM -0800, Charlie Jenkins wrote: > On Fri, Jan 24, 2025 at 02:06:08PM +0100, Luca Ceresoli wrote: > > Building perf in-tree is broken after commit 890a1961c812 ("perf tools: > > Create source symlink in perf object dir") which added a 'source' symlink > > in the output dir pointing to the source dir. > > > > With in-tree builds, the added 'SOURCE = ...' line is executed multiple > > times (I observed 2 during the build plus 2 during installation). This is a > > minor inefficiency, in theory not harmful because symlink creation is > > assumed to be idempotent. But it is not. > > > > Considering with in-tree builds: > > > > srctree=/absolute/path/to/linux > > OUTPUT=/absolute/path/to/linux/tools/perf > > > > here's what happens: > > > > 1. ln -sf $(srctree)/tools/perf $(OUTPUT)/source > > -> creates /absolute/path/to/linux/tools/perf/source > > link to /absolute/path/to/linux/tools/perf > > => OK, that's what was intended > > 2. ln -sf $(srctree)/tools/perf $(OUTPUT)/source # same command as 1 > > -> creates /absolute/path/to/linux/tools/perf/perf > > link to /absolute/path/to/linux/tools/perf > > => Not what was intended, not idempotent > > 3. Now the build _should_ create the 'perf' executable, but it fails > > > > The reason is the tricky 'ln' command line. At the first invocation 'ln' > > uses the 1st form: > > > > ln [OPTION]... [-T] TARGET LINK_NAME > > > > and creates a link to TARGET *called LINK_NAME*. > > > > At the second invocation $(OUTPUT)/source exists, so 'ln' uses the 3rd > > form: > > > > ln [OPTION]... TARGET... DIRECTORY > > > > and creates a link to TARGET *called TARGET* inside DIRECTORY. > > > > Fix by adding --no-dereference to "treat LINK_NAME as a normal file if it > > is a symbolic link to a directory", as the manpage says. > > > > Link: https://lore.kernel.org/all/20241125182506.38af9907@booty/ > > Fixes: 890a1961c812 ("perf tools: Create source symlink in perf object dir") > > Signed-off-by: Luca Ceresoli > > --- > > tools/perf/Makefile.perf | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf > > index d74241a151313bd09101aabb5d765a5a0a6efc84..bbd799a0fd544db220f29d1e250a819a765d04f3 100644 > > --- a/tools/perf/Makefile.perf > > +++ b/tools/perf/Makefile.perf > > @@ -164,7 +164,7 @@ ifneq ($(OUTPUT),) > > VPATH += $(OUTPUT) > > export VPATH > > # create symlink to the original source > > -SOURCE := $(shell ln -sf $(srctree)/tools/perf $(OUTPUT)/source) > > +SOURCE := $(shell ln -sf --no-dereference $(srctree)/tools/perf $(OUTPUT)/source) > > The kernel Makefile has: > $(Q)ln -fsn $(srcroot) source > > So for parity the --no-dereference could become `n`, but it doesn't > really matter. I can make the change. > > > endif > > > > ifeq ($(V),1) > > > > --- > > base-commit: ffd294d346d185b70e28b1a28abe367bbfe53c04 > > change-id: 20250124-perf-fix-intree-build-fbd97f560254 > > > > Best regards, > > -- > > Luca Ceresoli > > > > Reviewed-by: Charlie Jenkins > Tested-by: Charlie Jenkins Thanks for your review! Namhyung