Re: [PATCH v2] riscv: selftests: Fix warnings pointer masking test

From: Charlie Jenkins <charlie@rivosinc.com>
To: Alexandre Ghiti <alex@ghiti.fr>
Cc: Shuah Khan <shuah@kernel.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Samuel Holland <samuel.holland@sifive.com>,
	linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	Palmer Dabbelt <palmer@rivosinc.com>
Subject: Re: [PATCH v2] riscv: selftests: Fix warnings pointer masking test
Date: Thu, 5 Dec 2024 13:31:59 -0800	[thread overview]
Message-ID: <Z1Ibz-j8LUad571l@ghost> (raw)
In-Reply-To: <697a402b-0305-489d-bf4e-aa5e7fa4b2aa@ghiti.fr>

On Thu, Dec 05, 2024 at 09:11:46AM +0100, Alexandre Ghiti wrote:
> Hi Charlie,
> 
> On 05/12/2024 03:57, Charlie Jenkins wrote:
> > When compiling the pointer masking tests with -Wall this warning
> > is present:
> > 
> > pointer_masking.c: In function ‘test_tagged_addr_abi_sysctl’:
> > pointer_masking.c:203:9: warning: ignoring return value of ‘pwrite’
> > declared with attribute ‘warn_unused_result’ [-Wunused-result]
> >    203 |         pwrite(fd, &value, 1, 0); |
> >        ^~~~~~~~~~~~~~~~~~~~~~~~ pointer_masking.c:208:9: warning:
> > ignoring return value of ‘pwrite’ declared with attribute
> > ‘warn_unused_result’ [-Wunused-result]
> >    208 |         pwrite(fd, &value, 1, 0);
> > 
> > I came across this on riscv64-linux-gnu-gcc (Ubuntu
> > 11.4.0-1ubuntu1~22.04).
> > 
> > Fix this by checking that the number of bytes written equal the expected
> > number of bytes written.
> > 
> > Fixes: 7470b5afd150 ("riscv: selftests: Add a pointer masking test")
> > Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> > ---
> > Changes in v2:
> > - I had ret != 2 for testing, I changed it to be ret != 1.
> > - Link to v1: https://lore.kernel.org/r/20241204-fix_warnings_pointer_masking_tests-v1-1-ea1e9665ce7a@rivosinc.com
> > ---
> >   tools/testing/selftests/riscv/abi/pointer_masking.c | 19 +++++++++++++++----
> >   1 file changed, 15 insertions(+), 4 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/riscv/abi/pointer_masking.c b/tools/testing/selftests/riscv/abi/pointer_masking.c
> > index dee41b7ee3e3..229d85ccff50 100644
> > --- a/tools/testing/selftests/riscv/abi/pointer_masking.c
> > +++ b/tools/testing/selftests/riscv/abi/pointer_masking.c
> > @@ -189,6 +189,7 @@ static void test_tagged_addr_abi_sysctl(void)
> >   {
> >   	char value;
> >   	int fd;
> > +	int ret;
> >   	ksft_print_msg("Testing tagged address ABI sysctl\n");
> > @@ -200,14 +201,24 @@ static void test_tagged_addr_abi_sysctl(void)
> >   	}
> >   	value = '1';
> > -	pwrite(fd, &value, 1, 0);
> > +	ret = pwrite(fd, &value, 1, 0);
> > +	if (ret != 1) {
> > +		ksft_test_result_fail("Write to /proc/sys/abi/tagged_addr_disabled failed.\n");
> > +		return;
> > +	}
> > +
> >   	ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == -EINVAL,
> >   			 "sysctl disabled\n");
> >   	value = '0';
> > -	pwrite(fd, &value, 1, 0);
> > -	ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == 0,
> > -			 "sysctl enabled\n");
> > +	ret = pwrite(fd, &value, 1, 0);
> > +	if (ret != 1) {
> > +		ksft_test_result_fail("Write to /proc/sys/abi/tagged_addr_disabled failed.\n");
> > +		return;
> > +	}
> > +
> > +	ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == -EINVAL,
> > +			 "sysctl disabled\n");
> 
> Why did you change the test from 0 to -EINVAL here?

Thank you for pointing that out, copy-paste issue, I will revert that change!

- Charlie

> 
> Thanks,
> 
> Alex
> 
> 
> >   	set_tagged_addr_ctrl(0, false);
> > 
> > ---
> > base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
> > change-id: 20241204-fix_warnings_pointer_masking_tests-3860e4f35429