Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.117.160 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.117.160; helo=mail.nvidia.com; pr=C
Message-ID: <c30ff285-176f-4d76-38a0-4917a1c55c2b@nvidia.com>
Date:   Mon, 10 Jul 2023 17:58:30 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.12.0
Subject: Re: [PATCH] selftests/arm64: fix build failure during the
 "emit_tests" step
Content-Language: en-US
To:     Andrew Morton <akpm@linux-foundation.org>
CC:     Anders Roxell <anders.roxell@linaro.org>,
        David Hildenbrand <david@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Muhammad Usama Anjum <usama.anjum@collabora.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Peter Xu <peterx@redhat.com>, Shuah Khan <shuah@kernel.org>,
        <linux-arm-kernel@lists.infradead.org>, <linux-mm@kvack.org>,
        <linux-kselftest@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "Mark Brown" <broonie@kernel.org>
References: <20230711005629.2547838-1-jhubbard@nvidia.com>
From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20230711005629.2547838-1-jhubbard@nvidia.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jul 2023 00:58:42.7701
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 7f3af72f-5c36-484e-b305-08db81a9f8fd
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT075.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4516
X-Spam-Status: No, score=-1.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        NICE_REPLY_A,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,
        SPF_NONE,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=no
        autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 7/10/23 17:56, John Hubbard wrote:
> The build failure reported in [1] occurred because commit 9fc96c7c19df
> ("selftests: error out if kernel header files are not yet built") added
> a new "kernel_header_files" dependency to "all", and that triggered
> another, pre-existing problem. Specifically, the arm64 selftests
> override the emit_tests target, and that override improperly declares
> itself to depend upon the "all" target.

I also have a corresponding fix for selftests/riscv, which has copied the
arm64 selftest approach. But I'll wait to see how reviews go here,
before sending that out.

thanks,
-- 
John Hubbard
NVIDIA

> 
> This is a problem because the "emit_tests" target in lib.mk was not
> intended to be overridden. emit_tests is a very simple, sequential build
> target that was originally invoked from the "install" target, which in
> turn, depends upon "all".
> 
> That approach worked for years. But with 9fc96c7c19df in place,
> emit_tests failed, because it does not set up all of the elaborate
> things that "install" does. And that caused the new
> "kernel_header_files" target (which depends upon $(KBUILD_OUTPUT) being
> correct) to fail.
> 
> Some detail: The "all" target is .PHONY. Therefore, each target that
> depends on "all" will cause it to be invoked again, and because
> dependencies are managed quite loosely in the selftests Makefiles, many
> things will run, even "all" is invoked several times in immediate
> succession. So this is not a "real" failure, as far as build steps go:
> everything gets built, but "all" reports a problem when invoked a second
> time from a bad environment.
> 
> To fix this, simply remove the unnecessary "all" dependency from the
> overridden emit_tests target. The dependency is still effectively
> honored, because again, invocation is via "install", which also depends
> upon "all".
> 
> An alternative approach would be to harden the emit_tests target so that
> it can depend upon "all", but that's a lot more complicated and hard to
> get right, and doesn't seem worth it, especially given that emit_tests
> should probably not be overridden at all.
> 
> [1] https://lore.kernel.org/20230710-kselftest-fix-arm64-v1-1-48e872844f25@kernel.org
> 
> Fixes: 9fc96c7c19df ("selftests: error out if kernel header files are not yet built")
> Reported-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
>   tools/testing/selftests/arm64/Makefile | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
> index 9460cbe81bcc..ace8b67fb22d 100644
> --- a/tools/testing/selftests/arm64/Makefile
> +++ b/tools/testing/selftests/arm64/Makefile
> @@ -42,7 +42,7 @@ run_tests: all
>   	done
>   
>   # Avoid any output on non arm64 on emit_tests
> -emit_tests: all
> +emit_tests:
>   	@for DIR in $(ARM64_SUBTARGETS); do				\
>   		BUILD_TARGET=$(OUTPUT)/$$DIR;			\
>   		make OUTPUT=$$BUILD_TARGET -C $$DIR $@;		\
> 
> base-commit: d5fe758c21f4770763ae4c05580be239be18947d