From nobody Mon Nov 25 08:00:59 2024 Received: from mail-yb1-f201.google.com (mail-yb1-f201.google.com [209.85.219.201]) (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 70E92198A0D for ; Wed, 30 Oct 2024 04:59:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730264373; cv=none; b=Ag1xJ3/9BFfvXVx3I8gv1rzV4E+QpkRpuLkMz+pobith8mhBoYTADvGxBVwG3qBd2X7fMt39RRzQv+5oO0pHM441Y9ruKMXilb+WoQySmKAGuDgcvjG/4n7cktNcbVxYzLLJW8YG/o68X3pI22FWA2/Qh9Ej6OhhP79w7nji2Uo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730264373; c=relaxed/simple; bh=ckB9pUMTNSWy4prV1cOfoPbmEn3v96IADds04sKuQUM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=OEqhRGleur/DY5i4o8bNyefAj1O4GjVZULDNMAbuZbOj9aq0HbpAmv0KDktNxq8/VCcvoIN/omZh1oHNiep891VbICmqEckwVmtnKYqR/DlDRXW5uOTXKkkZl4SbwG3k6D3o6Y9jcEPWISQYxYea1meGPHl7p0B4dukKQSVwQm8= 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=NbmhR6S9; arc=none smtp.client-ip=209.85.219.201 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="NbmhR6S9" Received: by mail-yb1-f201.google.com with SMTP id 3f1490d57ef6-e02b5792baaso10362719276.2 for ; Tue, 29 Oct 2024 21:59:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730264369; x=1730869169; 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=FDWFvWINPVq6lF2SwqYloaVF+/6pFtfjGvv1V4TTOR4=; b=NbmhR6S974n+ai2b4Qud6M1FvQaoW2Ur6A0b+gM3CnyOni2Hu5wTAMNC7W598m97si TctBB5qV9nxUskP8XtQj1fYI3m/KKZxBoltwX08xBb6ZQuVoLiPI3Ik/uMFh2Gi/WbG7 +IrSQXkXaYUhG9L1c12uhr/tDwmflhm+wzTW+MpCsjl6QrYqwqMivKg8SSOmHBZmJsFc 51R8ABuNsRn7JLq+8GtHaIADlNXXMSdHGmBOzrKxC2olC2HprfbK3OUd1/9+QE2sqEvi H/LTD8nMzARq9SsNzerAcZFRwZy2Xv2boN39gQ7uR+I7s+9cowG+R001kNLXQSyjvjCB UpAQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730264369; x=1730869169; 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=FDWFvWINPVq6lF2SwqYloaVF+/6pFtfjGvv1V4TTOR4=; b=t24MqWWIuJC3/fOX55/0jxZ47eyoIU6lk+tK5qu/Nh2aw4133ceKwbAuOwraxRkR7k mxfvASPR0mGwbFZ65NrVn/0x09yI819jXYPLTHf5LMlVcJWEySXPA95bSKEqyxmM3dVv Fzia3Ffli0urIu3Ie39TW0dcVX9WC1TFhdAT+fAJn/tLUOJc6S52QqeQRFnueTaG4GPQ vOBIMcMqTDuIL7p3M8/OxcRvTUzf9RbISRTX5JVVNMzZ63YK7TXPh04CbqQwi0KmXiXJ NvdDLPcDs2XAdtQNClBLfpNHqSmsykuyMDPe9hjbSRlvo0vuTIUkdEczIo07crG6QEx9 sNEA== X-Forwarded-Encrypted: i=1; AJvYcCVxdV8bp3BPdoEi3HGNqssaOLUQOWvyzp9XeDvPWCRYEOWskirU79ovQadOuX4CbJ3gbAoc0sHi8n93wus=@vger.kernel.org X-Gm-Message-State: AOJu0YxZvRdxaMIrsC3CZ+eAvbMwKQ+S9M/BMRHo3m8lMb6dm560/edZ 6FL85QrA3VDGrch+SABap2AsmO5QE8yamAR4DclGgSvE3dV0I39R6Y1ytglMOX95Pp3iKT5kgVO 37AunQE7x9w== X-Google-Smtp-Source: AGHT+IGekxcLmEJS2haephcXYwaPtTFGVJy9oILsQ6O/T5joWShJw7lDLxlgK2wdbCm786occ2gOaxQlBRU5Nw== X-Received: from slicestar.c.googlers.com ([fda3:e722:ac3:cc00:b1:7045:ac11:6237]) (user=davidgow job=sendgmr) by 2002:a25:a549:0:b0:e30:c6ce:1165 with SMTP id 3f1490d57ef6-e30c6ce1d94mr23975276.1.1730264369395; Tue, 29 Oct 2024 21:59:29 -0700 (PDT) Date: Wed, 30 Oct 2024 12:57:16 +0800 In-Reply-To: <20241030045719.3085147-2-davidgow@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20241030045719.3085147-2-davidgow@google.com> X-Mailer: git-send-email 2.47.0.163.g1226f6d8fa-goog Message-ID: <20241030045719.3085147-8-davidgow@google.com> Subject: [PATCH v3 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-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 --- No changes since v2: https://lore.kernel.org/linux-kselftest/20241029092422.2884505-4-davidgow@g= oogle.com/ 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 ac296467a552..d5926f7ef405 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