From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (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 C6941204924 for ; Tue, 29 Oct 2024 09:24:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730193888; cv=none; b=tEur39V3dYE4pIA2YRXOF2O5Ey+86FbCoJA1ZyrX6b7OkJDhppjMMQMIo5dgMFc7UD8iCRu+h4rQsueUmb0WC6neY7eJ934oXhcXL1k2xtacohp1aWfCwp4Ab+WXR/5Q1r8XQm5hOl26Z9CkQELg8sBvcTA70YnQnNlDSfdym8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730193888; c=relaxed/simple; bh=lvKDYgMcSvvhTyIBb6ECAc1q865WqLsWsBgNoK5wF70=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=aZo/yzyHjPqmciyGdfA4y0t4l43wUeH2+w12LLbhONpNjTKtxkUhzd2h7DfNiMMOXKKujaGOXyJerMEoxSq5O8NqCPh+8GITQ/Hv0U+2H8iuri2l2qdY/QVkjDZu+pIA7TzCsVXBGRTQ7T8455a52XyueSMqwp/37st1mzGG1JI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--davidgow.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=NWsuspQ4; arc=none smtp.client-ip=209.85.128.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--davidgow.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NWsuspQ4" Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-6e7fb84f999so78033247b3.2 for ; Tue, 29 Oct 2024 02:24:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730193885; x=1730798685; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=ci1oKFH7l7WT9pl4IwsUJvvMv23hze9L/lrXNyoJlVo=; b=NWsuspQ4VW5XaQgZXor47tgDVdnrt9Fq80ycCRpfD4phtzLiR/T7C2X4JImcNhwsTY o93zF+dQUTDr5VD+m7UgKWfEzLfoSmmug8FCtLOgeMkrAhxpRH6FcZ8IT7sW/lVxrqUv wonhjgnHysSjYPah294jE28LVB/cNcEe1jTCr1ZwDWQj69d/uS9vDjUxTi+7C6OCYfV7 tIxTnnDOsaVuoVKHZHXyF0HPx1l0X2SE37DzSJz7Vfy8Ss39IUMsykztOfBrX1/n/Z35 8+AAKLoo39AznLENhwdD80zIFr3pIlaALJuNeBWA6cvwRfZiFfeBSPZIXP4ljG041Mda lk3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730193885; x=1730798685; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=ci1oKFH7l7WT9pl4IwsUJvvMv23hze9L/lrXNyoJlVo=; b=QFo/niKH66QJH9kPuI6trCpZPGHMiDFRdoiR1+5YUN1KwKO3xKatbT38Nc1aavld+i UjcWGahqwyFTd/sZZ11HOtSt1Ce0nfZD8stzdIEnY01ZPUsKxUYmyh3yqD8UsA/OnlTx nMx0S1cGHXljISJtwmLZQbtosh/A5bAVd4JYiRB5UGUBpqZu5H7BwL7MkgwVlJJXwlIR 4IR/p9uMbyWx4/t10Wkkygtp//vzwxzxUUzUpee4pmzaJcv3P3BqbW0yO90IgkKuxbv7 NExi8Aj3JckqnjkeziQLxdDqCmP1p2j/31yqWhyyHjjKCnrZdDVQoWZKRCVwJo9CjCZW i8dA== X-Forwarded-Encrypted: i=1; AJvYcCUjoXs5z1ScigVQ7n/zA2VLQBGnMhVZ7MbsIM4Bi5pLd4DKSg0nNPxQpjk5jON41Np00zx2Btr7xHpIvsJXuQ==@vger.kernel.org X-Gm-Message-State: AOJu0YzhU6Bbp3yT3McJDFr21yX2+FNJZYf4tvuMICcqxFiNCqkrCYqV 1ZamzeZqpEV1EeL8UcSxjXWz0UsNjMGzOXFYcLNo1yyq1zZ+tzJUQCbnVsgxo6GyVL8HviZsx9I uQfEKiE+WaQ== X-Google-Smtp-Source: AGHT+IEqlyW4/tadreX6bN11wpCmzXQCZWMdmwaTsthqhgrxW9b3cNSTo/5NH/qdY8Gte5je22w3U1+J/ieEyw== X-Received: from slicestar.c.googlers.com ([fda3:e722:ac3:cc00:b1:7045:ac11:6237]) (user=davidgow job=sendgmr) by 2002:a5b:2ca:0:b0:e30:bf92:7a64 with SMTP id 3f1490d57ef6-e30bf927b96mr1319276.2.1730193884736; Tue, 29 Oct 2024 02:24:44 -0700 (PDT) Date: Tue, 29 Oct 2024 17:24:19 +0800 In-Reply-To: <20241029092422.2884505-1-davidgow@google.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241029092422.2884505-1-davidgow@google.com> X-Mailer: git-send-email 2.47.0.163.g1226f6d8fa-goog Message-ID: <20241029092422.2884505-4-davidgow@google.com> Subject: [PATCH v2 3/3] rust: kunit: allow to know if we are in a test From: David Gow To: Miguel Ojeda , "=?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?=" , Brendan Higgins , Rae Moar , Boqun Feng , Alex Gaynor , Gary Guo , Benno Lossin , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Alice Ryhl , Matt Gilbride Cc: kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, David Gow Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: Jos=C3=A9 Exp=C3=B3sito In some cases, we need to call test-only code from outside the test case, for example, to mock a function or a module. In order to check whether we are in a test or not, we need to test if `CONFIG_KUNIT` is set. Unfortunately, we cannot rely only on this condition because: - a test could be running in another thread, - some distros compile KUnit in production kernels, so checking at runtime that `current->kunit_test !=3D NULL` is required. Forturately, KUnit provides an optimised check in `kunit_get_current_test()`, which checks CONFIG_KUNIT, a global static key, and then the current thread's running KUnit test. Add a safe wrapper function around this to know whether or not we are in a KUnit test and examples showing how to mock a function and a module. Signed-off-by: Jos=C3=A9 Exp=C3=B3sito Co-developed-by: David Gow Signed-off-by: David Gow --- Changes since v1: https://lore.kernel.org/lkml/20230720-rustbind-v1-3-c80db349e3b5@google.com= / - Rebased on top of rust-next. - Use the `kunit_get_current_test()` C function, which wasn't previously available, instead of rolling our own. - (Thanks also to Boqun for suggesting a nicer way of implementing this, which I tried, but the `kunit_get_current_test()` version obsoleted.) --- rust/kernel/kunit.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 72 insertions(+) diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs index abcf0229ffee..bfc80394546a 100644 --- a/rust/kernel/kunit.rs +++ b/rust/kernel/kunit.rs @@ -272,11 +272,83 @@ macro_rules! kunit_unsafe_test_suite { }; } =20 +/// In some cases, you need to call test-only code from outside the test c= ase, for example, to +/// create a function mock. This function can be invoked to know whether w= e are currently running a +/// KUnit test or not. +/// +/// # Examples +/// +/// This example shows how a function can be mocked to return a well-known= value while testing: +/// +/// ``` +/// # use kernel::kunit::in_kunit_test; +/// # +/// fn fn_mock_example(n: i32) -> i32 { +/// if in_kunit_test() { +/// 100 +/// } else { +/// n + 1 +/// } +/// } +/// +/// let mock_res =3D fn_mock_example(5); +/// assert_eq!(mock_res, 100); +/// ``` +/// +/// Sometimes, you don't control the code that needs to be mocked. This ex= ample shows how the +/// `bindings` module can be mocked: +/// +/// ``` +/// // Import our mock naming it as the real module. +/// #[cfg(CONFIG_KUNIT)] +/// use bindings_mock_example as bindings; +/// +/// // This module mocks `bindings`. +/// mod bindings_mock_example { +/// use kernel::kunit::in_kunit_test; +/// use kernel::bindings::u64_; +/// +/// // Make the other binding functions available. +/// pub(crate) use kernel::bindings::*; +/// +/// // Mock `ktime_get_boot_fast_ns` to return a well-known value when= running a KUnit test. +/// pub(crate) unsafe fn ktime_get_boot_fast_ns() -> u64_ { +/// if in_kunit_test() { +/// 1234 +/// } else { +/// unsafe { kernel::bindings::ktime_get_boot_fast_ns() } +/// } +/// } +/// } +/// +/// // This is the function we want to test. Since `bindings` has been moc= ked, we can use its +/// // functions seamlessly. +/// fn get_boot_ns() -> u64 { +/// unsafe { bindings::ktime_get_boot_fast_ns() } +/// } +/// +/// let time =3D get_boot_ns(); +/// assert_eq!(time, 1234); +/// ``` +pub fn in_kunit_test() -> bool { + // SAFETY: kunit_get_current_test() is always safe to call from C (it = has fallbacks for + // when KUnit is not enabled), and we're only comparing the result to = NULL. + unsafe { !bindings::kunit_get_current_test().is_null() } +} + #[kunit_tests(rust_kernel_kunit)] mod tests { + use super::*; + #[test] fn rust_test_kunit_kunit_tests() { let running =3D true; assert_eq!(running, true); } + + #[test] + fn rust_test_kunit_in_kunit_test() { + let in_kunit =3D in_kunit_test(); + assert_eq!(in_kunit, true); + } } --=20 2.47.0.163.g1226f6d8fa-goog