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

[Charlie Jenkins]

On Thu, Dec 05, 2024 at 09:04:12AM +0100, Andrew Jones wrote:
> On Wed, Dec 04, 2024 at 06:57:10PM -0800, 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@xxxxxxxxxxxx>
> > ---
> > 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@xxxxxxxxxxxx
> > ---
> >  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;
> > +	}
> 
> Could make a wrapper function for pwrite() to avoid duplicating the ret
> value check.

I'll change it to a goto statement to avoid duplicating the
ksft_test_result_fail call.

> 
> > +
> > +	ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == -EINVAL,
> > +			 "sysctl disabled\n");
> 
> Why is this changed from expecting 0 for the return and being the
> "sysctrl enabled" test? We still write '0' to tagged_addr_disabled here.

Silly copy mistake, thank you!

> 
> >  
> >  	set_tagged_addr_ctrl(0, false);
> >  
> > 
> > ---
> > base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
> > change-id: 20241204-fix_warnings_pointer_masking_tests-3860e4f35429
> > -- 
> > - Charlie
> >
> 
> Not part of this patch, but now that I looked at
> test_tagged_addr_abi_sysctl() I see that
> ksft_test_result_skip() is duplicated.

Oh huh I hadn't noticed that. I'll send a patch for that I guess, easy
fix.

- Charlie

> 
> Thanks,
> drew
> 
> > 
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