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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=n4F13XQgVfHrFjDyFI3dMs7NsVDxr8/9oSk7fc0QDng=; b=Z++QrbCRQM+I9iKj2YyWAJU0uqwMkYxeKd+DaliBbxabA3LmEmSRIb72qqP59Up2kK +CSh56FnBlXhQiWHnSBFNv2hS/d+CApcYnBmyf2UN6tMPy5IQI2hePTsqXYrd2GRpGDC Pyw3kNAH1WEI0JGYkkX12fT3ZIeX+aZ3ELElfOg10JIZ5Qz6LHgTLfnedcqNtPMYDnSK yXVlSdDsNIUhXHmAdGE19t6e3Z/YImqD8jkTzzsp81JO63fNdSIs19AWvzphH8H6BvRt 4Iw2FTymThOzQigXscMOmptOyq7Yzmr/kWQbMOWPuOZWSunON5JO7qNA4C9ZvvE9p9Is zhmQ== X-Gm-Message-State: AOAM530JndGLhaT0qB53RPzz5nltgy/TQx39AkpJJKB5zYkVWXsL3rfZ P2mdRdLTmkoiCL0DmYGpEl0ptiI+MIQ9qvlIpVdK1w== X-Google-Smtp-Source: ABdhPJzTazRGBk5tHZ5IA/YT481aZrqOv2RHiiBDcFVRQOVYSiPeM5kCIsHtyEdCdFkGD1Yr28LrnfqmQq+gR6UCRoM= X-Received: by 2002:a05:6402:1e8e:: with SMTP id f14mr20147051edf.250.1635890686722; Tue, 02 Nov 2021 15:04:46 -0700 (PDT) MIME-Version: 1.0 References: <20211029114312.1921603-1-anders.roxell@linaro.org> <834d18b6-4106-045f-0264-20e54edf47bc@linuxfoundation.org> In-Reply-To: From: Anders Roxell Date: Tue, 2 Nov 2021 23:04:35 +0100 Message-ID: Subject: Re: [PATCH] selftests: kselftest.h: mark functions with 'noreturn' To: Nick Desaulniers Cc: Shuah Khan , shuah@kernel.org, fenghua.yu@intel.com, reinette.chatre@intel.com, john.stultz@linaro.org, tglx@linutronix.de, akpm@linux-foundation.org, nathan@kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 89EB0B0000AF X-Stat-Signature: w164o7s7u4numm3ute5hih74j1su1zt1 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linaro.org header.s=google header.b="P4nJjt/f"; spf=pass (imf19.hostedemail.com: domain of anders.roxell@linaro.org designates 209.85.208.45 as permitted sender) smtp.mailfrom=anders.roxell@linaro.org; dmarc=pass (policy=none) header.from=linaro.org X-HE-Tag: 1635890681-424308 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000152, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, 30 Oct 2021 at 00:08, Nick Desaulniers wrote: > > On Fri, Oct 29, 2021 at 11:19 AM Shuah Khan wrote: > > > > On 10/29/21 5:43 AM, Anders Roxell wrote: > > > When building kselftests/capabilities the following warning shows up: > > > > > > clang -O2 -g -std=gnu99 -Wall test_execve.c -lcap-ng -lrt -ldl -o test_execve > > > test_execve.c:121:13: warning: variable 'have_outer_privilege' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] > > > } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) { > > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > test_execve.c:136:9: note: uninitialized use occurs here > > > return have_outer_privilege; > > > ^~~~~~~~~~~~~~~~~~~~ > > > test_execve.c:121:9: note: remove the 'if' if its condition is always true > > > } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) { > > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > test_execve.c:94:27: note: initialize the variable 'have_outer_privilege' to silence this warning > > > bool have_outer_privilege; > > > ^ > > > = false > > > > > > Rework so all the ksft_exit_*() functions have attribue > > > '__attribute__((noreturn))' so the compiler knows that there wont be > > > any return from the function. That said, without > > > '__attribute__((noreturn))' the compiler warns about the above issue > > > since it thinks that it will get back from the ksft_exit_skip() > > > function, which it wont. > > > Cleaning up the callers that rely on ksft_exit_*() return code, since > > > the functions ksft_exit_*() have never returned anything. > > > > > > Signed-off-by: Anders Roxell > > > > Lot of changes to fix this warning. Is this necessary? I would > > like to explore if there is an easier and localized change that > > can fix the problem. > > via `man 3 exit`: > ``` > The exit() function causes normal process termination ... > ... > RETURN VALUE > The exit() function does not return. > ``` > so seeing `ksft_exit_pass`, `ksft_exit_fail`, `ksft_exit_fail_msg`, > `ksft_exit_xfail`, `ksft_exit_xpass`, and `ksft_exit_skip` all > unconditional call `exit` yet return an `int` looks wrong to me on > first glance. So on that point this patch and its resulting diffstat > LGTM. I'll respin the patch with these changes only. > > That said, there are many changes that explicitly call `ksft_exit` > with an expression; are those setting the correct exit code? Note that > ksft_exit_pass is calling exit with KSFT_PASS which is 0. So some of > the negations don't look quite correct to me. For example: > > - return !ksft_get_fail_cnt() ? ksft_exit_pass() : ksft_exit_fail(); > + ksft_exit(!ksft_get_fail_cnt()); > > so if ksft_get_fail_cnt() returns 0, then we were calling > ksft_exit_pass() which exited with 0. Now we'd be exiting with 1? oh, right, thank you for your review. I will drop all the 'ksft_exit()' changes, they should be fixed and go in as separete patches. Cheers, Anders