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Message-ID: <Z1MyrgQJsHQscdZ2@ghost>
Date: Fri, 6 Dec 2024 09:21:50 -0800
From: Charlie Jenkins <charlie@...osinc.com>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: Shuah Khan <shuah@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Samuel Holland <samuel.holland@...ive.com>,
Alexandre Ghiti <alex@...ti.fr>, linux-kselftest@...r.kernel.org,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
Palmer Dabbelt <palmer@...osinc.com>
Subject: Re: [PATCH v4] riscv: selftests: Fix warnings pointer masking test
On Fri, Dec 06, 2024 at 10:15:17AM +0100, Andrew Jones wrote:
> On Thu, Dec 05, 2024 at 01:49:31PM -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@...osinc.com>
> > ---
> > Changes in v4:
> > - Skip sysctl_enabled test if first pwrite failed
> > - Link to v3: https://lore.kernel.org/r/20241205-fix_warnings_pointer_masking_tests-v3-1-5c28b0f9640d@rivosinc.com
> >
> > Changes in v3:
> > - Fix sysctl enabled test case (Drew/Alex)
> > - Move pwrite err condition into goto (Drew)
> > - Link to v2: https://lore.kernel.org/r/20241204-fix_warnings_pointer_masking_tests-v2-1-1bf0c5095f58@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 | 20 ++++++++++++++++++--
> > 1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/testing/selftests/riscv/abi/pointer_masking.c b/tools/testing/selftests/riscv/abi/pointer_masking.c
> > index dee41b7ee3e3..759445d5f265 100644
> > --- a/tools/testing/selftests/riscv/abi/pointer_masking.c
> > +++ b/tools/testing/selftests/riscv/abi/pointer_masking.c
> > @@ -189,6 +189,8 @@ static void test_tagged_addr_abi_sysctl(void)
> > {
> > char value;
> > int fd;
> > + int ret;
> > + char *err_pwrite_msg = "failed to write to /proc/sys/abi/tagged_addr_disabled\n";
> >
> > ksft_print_msg("Testing tagged address ABI sysctl\n");
> >
> > @@ -200,18 +202,32 @@ 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_skip(err_pwrite_msg);
>
> It seems like we should have a better way to keep the count balanced than
> to require a ksft_test_result_skip() call for each test on each error
> path. Every time we add a test we'll have to go add skips everywhere else.
It's only a problem if there are multiple tests in a single test
function like there is here. Since the tests disable then reenable it
makes sense to have them in one function, but does require us to do the
skipping.
>
> > + goto err_pwrite;
> > + }
> > +
> > ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == -EINVAL,
> > "sysctl disabled\n");
> >
> > value = '0';
> > - pwrite(fd, &value, 1, 0);
> > + ret = pwrite(fd, &value, 1, 0);
> > + if (ret != 1)
> > + goto err_pwrite;
> > +
> > ksft_test_result(set_tagged_addr_ctrl(min_pmlen, true) == 0,
> > "sysctl enabled\n");
> >
> > set_tagged_addr_ctrl(0, false);
> >
> > close(fd);
> > +
> > + return;
> > +
> > +err_pwrite:
> > + close(fd);
> > + ksft_test_result_fail(err_pwrite_msg);
> > }
>
> I don't think the goto reduces much code or improves readability much. A
> wrapper function should do better. I was thinking something like
>
> static bool pwrite_wrapper(int fd, void *buf, size_t count, const char *msg)
> {
> int ret = pwrite(fd, buf, count, 0);
> if (ret != count) {
> ksft_perror(msg);
> return false;
> }
> return true;
> }
>
>
> value = '1';
> if (!pwrite_wrapper(fd, &value, 1, "write '1'"))
> ksft_test_result_fail(...);
>
> value = '0';
> if (!pwrite_wrapper(fd, &value, 1, "write '0'"))
> ksft_test_result_fail(...);
>
>
Will do, thanks!
- Charlie
> >
> > static void test_tagged_addr_abi_pmlen(int pmlen)
> >
> > ---
> > base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
> > change-id: 20241204-fix_warnings_pointer_masking_tests-3860e4f35429
> > --
> > - Charlie
> >
>
> Thanks,
> drew
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