From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f49.google.com (mail-ed1-f49.google.com [209.85.208.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64ECF2C99 for ; Tue, 2 Nov 2021 22:04:48 +0000 (UTC) Received: by mail-ed1-f49.google.com with SMTP id 5so2387250edw.7 for ; Tue, 02 Nov 2021 15:04:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=n4F13XQgVfHrFjDyFI3dMs7NsVDxr8/9oSk7fc0QDng=; b=P4nJjt/fXf671D9eUvZ9+y2bS+QDywI1rCVkTQODwOQV83TwA4krXZ7DTRv5643PYu nMXoWLhAOqQBTli5Xrp/KuciRht6NbwzCpTkhpKUxgRFTYGZqdUrZatUog5rJSs2lgfX H6N6qANOFFyiXZvTthW1CuCVJ0KXY4zPBZuHt48oUWyz7Ayj3g9Ooc4FgS6CFJV6h5CY Lbmoz5D1O8xBo+glIM6hvtuQctVF6/T2kHB1n8bmxK8tALLMaAH9NRZb2/MkJ+mLParS RIDHAd2t3NPegMZM91FO1Zejd4HVII8jRLkmTu7iNKMf59bppokv5o2c09jEw+LX5pn8 v4Ng== X-Google-DKIM-Signature: v=1; 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=cQdMiRYoyp/mDJ3ig8nAvdkNSu5vwd0IxhBI0OP7TRcJw/HqfWtUAlvF83v97VOyBv YYwvhNCEe6hFAu1PRV2PZC6/HFTbSsU3vJgRWd1HusBVHXoOwFoDK5ox20ud1uQvwuXp rixhHMztkjmcEnMJYLUbel5I/ivvQKaSJ2Aey3FnTjM6r4MjybvC5R9VyNRPpjIwoZuN d8fAHQurjn/b6j6J58muyJtF7/MYtgZnEk2puhGISPKWTMhnBvOFsAZejVzKXQHOoinZ WSItLBZyWGEw2qnkyWUfv/Hx3+qvGo4iNf7ZfoHZJ1yL88BQUFiEDOf8YJ+zKPjHpEUT KHlw== X-Gm-Message-State: AOAM533bM33EQUarK0yelLIYzjABiXuFyTi8DvETeuuyN9cfBSkX/KVY 2ObDOJT0Gqf/KtiV1078XE7U9b8YkVdeUlJtcftnrA== 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) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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" 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