linux-kernel - Re: selftests/filesystem: clang warning null passed to a callee that requires a non-null argument [-Wnonnull]

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Message-ID: <aEnLJ0CkfrHieKrG@stanley.mountain>
Date: Wed, 11 Jun 2025 21:29:59 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Nathan Chancellor <nathan@...nel.org>,
	Christian Brauner <brauner@...nel.org>,
	Jeff Layton <jlayton@...nel.org>
Cc: Naresh Kamboju <naresh.kamboju@...aro.org>,
	clang-built-linux <llvm@...ts.linux.dev>,
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	lkft-triage@...ts.linaro.org,
	Anders Roxell <anders.roxell@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, Sasha Levin <sashal@...nel.org>
Subject: Re: selftests/filesystem: clang warning null passed to a callee that
 requires a non-null argument [-Wnonnull]

On Wed, Jun 11, 2025 at 10:50:52AM -0700, Nathan Chancellor wrote:
> On Wed, Jun 11, 2025 at 07:47:39PM +0300, Dan Carpenter wrote:
> > This seems like a Clang bug, right?  The test for _Nullable is reversed
> > or something?
> 
> My copy of unistd.h has
> 
>   /* Execute program relative to a directory file descriptor.  */
>   extern int execveat (int __fd, const char *__path, char *const __argv[],
>                        char *const __envp[], int __flags)
>       __THROW __nonnull ((2, 3));
> 
> so I think the warning is valid in this case. I will note that
> tools/testing/selftests/exec/recursion-depth.c uses execve() with a NULL
> argv and disables -Wnonnull so maybe that should happen for this test
> case too? Or should that NULL be changed into a ""?
> 

Oh, huh.  The man page for execveat() says _Nullable but the headerfile
says the opposite.

regards,
dan carpenter

> > On Thu, Jun 05, 2025 at 05:41:01PM +0530, Naresh Kamboju wrote:
> > > Regressions found on arm, arm64 and x86_64 building warnings with clang-20
> > > and clang-nightly started from Linux next-20250603
> > > 
> > > Regressions found on arm, arm64 and x86_64
> > >  - selftests/filesystem
> > > 
> > > Regression Analysis:
> > >  - New regression? Yes
> > >  - Reproducible? Yes
> > > 
> > > First seen on the next-20250603
> > > Good: next-20250530
> > > Bad:  next-20250603
> > > 
> > > Test regression: arm arm64 x86_64 clang warning null passed to a
> > > callee that requires a non-null argument [-Wnonnull]
> > > 
> > > Reported-by: Linux Kernel Functional Testing <lkft@...aro.org>
> > > 
> > > ## Build warnings
> > > make[4]: Entering directory '/builds/linux/tools/testing/selftests/filesystems'
> > >   CC       devpts_pts
> > >   CC       file_stressor
> > >   CC       anon_inode_test
> > > anon_inode_test.c:45:37: warning: null passed to a callee that
> > > requires a non-null argument [-Wnonnull]
> > >    45 |         ASSERT_LT(execveat(fd_context, "", NULL, NULL,
> > > AT_EMPTY_PATH), 0);
> > >       |                                            ^~~~
> > > 
> > > ## Source
> > > * Kernel version: 6.15.0-next-20250605
> > > * Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
> > > * Git sha: a0bea9e39035edc56a994630e6048c8a191a99d8
> > > * Toolchain: Debian clang version 21.0.0
> > > (++20250529012636+c474f8f2404d-1~exp1~20250529132821.1479)
> > > 
> > > ## Build
> > > * Test log: https://qa-reports.linaro.org/api/testruns/28651387/log_file/
> > > * Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/2xzM4wMl8SvuLKE3mw3csiuv3Jz/
> > > * Kernel config:
> > > https://storage.tuxsuite.com/public/linaro/lkft/builds/2xzM4wMl8SvuLKE3mw3csiuv3Jz/config
> > > 
> > > --
> > > Linaro LKFT
> > > https://lkft.linaro.org