[PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

[PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

[André Almeida]

Instead of just checking if the syscall failed as expected, check as
well what is the error code returned, to check if it's match the
expectation and it's failing in the correct error path inside the
kernel.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
This patch is aimed for 6.18
---
 .../futex/functional/futex_numa_mpol.c        | 36 +++++++++++--------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
index 802c15c82190..c84441751235 100644
--- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
+++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
@@ -77,7 +77,7 @@ static void join_max_threads(void)
 	}
 }
 
-static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flags)
+static void __test_futex(void *futex_ptr, int err_value, unsigned int futex_flags)
 {
 	int to_wake, ret, i, need_exit = 0;
 
@@ -88,11 +88,17 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 
 	do {
 		ret = futex2_wake(futex_ptr, to_wake, futex_flags);
-		if (must_fail) {
-			if (ret < 0)
-				break;
-			ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
-					   to_wake, futex_flags);
+
+		if (err_value) {
+			if (ret >= 0)
+				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
+						   to_wake, futex_flags);
+
+			if (errno != err_value)
+				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) expected error was %d, but returned %d (%s)\n",
+						   to_wake, futex_flags, err_value, errno, strerror(errno));
+
+			break;
 		}
 		if (ret < 0) {
 			ksft_exit_fail_msg("Failed futex2_wake(%d, 0x%x): %m\n",
@@ -106,12 +112,12 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 	join_max_threads();
 
 	for (i = 0; i < MAX_THREADS; i++) {
-		if (must_fail && thread_args[i].result != -1) {
+		if (err_value && thread_args[i].result != -1) {
 			ksft_print_msg("Thread %d should fail but succeeded (%d)\n",
 				       i, thread_args[i].result);
 			need_exit = 1;
 		}
-		if (!must_fail && thread_args[i].result != 0) {
+		if (!err_value && thread_args[i].result != 0) {
 			ksft_print_msg("Thread %d failed (%d)\n", i, thread_args[i].result);
 			need_exit = 1;
 		}
@@ -120,14 +126,14 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 		ksft_exit_fail_msg("Aborting due to earlier errors.\n");
 }
 
-static void test_futex(void *futex_ptr, int must_fail)
+static void test_futex(void *futex_ptr, int err_value)
 {
-	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
+	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
 }
 
-static void test_futex_mpol(void *futex_ptr, int must_fail)
+static void test_futex_mpol(void *futex_ptr, int err_value)
 {
-	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
+	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
 }
 
 static void usage(char *prog)
@@ -184,16 +190,16 @@ int main(int argc, char *argv[])
 
 	/* FUTEX2_NUMA futex must be 8-byte aligned */
 	ksft_print_msg("Mis-aligned futex\n");
-	test_futex(futex_ptr + mem_size - 4, 1);
+	test_futex(futex_ptr + mem_size - 4, 22);
 
 	futex_numa->numa = FUTEX_NO_NODE;
 	mprotect(futex_ptr, mem_size, PROT_READ);
 	ksft_print_msg("Memory, RO\n");
-	test_futex(futex_ptr, 1);
+	test_futex(futex_ptr, 14);
 
 	mprotect(futex_ptr, mem_size, PROT_NONE);
 	ksft_print_msg("Memory, no access\n");
-	test_futex(futex_ptr, 1);
+	test_futex(futex_ptr, 14);
 
 	mprotect(futex_ptr, mem_size, PROT_READ | PROT_WRITE);
 	ksft_print_msg("Memory back to RW\n");
-- 
2.51.0

[PATCH 2/2] selftest/futex: Reintroduce "Memory out of range" numa_mpol's subtest

[André Almeida]

Commit d8e2f919997 ("selftests/futex: Fix some futex_numa_mpol
subtests") removed the "Memory out of range" subtest due to it being
dependent on the memory layout of the test process having an invalid
memory address just after the `*futex_ptr` allocated memory.

Reintroduce this test and make it deterministic, by allocation two
memory pages and marking the second one with PROT_NONE.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
This patch is aimed for 6.18
---
 .../testing/selftests/futex/functional/futex_numa_mpol.c  | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
index c84441751235..e4b840184b1d 100644
--- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
+++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
@@ -174,10 +174,13 @@ int main(int argc, char *argv[])
 	ksft_set_plan(1);
 
 	mem_size = sysconf(_SC_PAGE_SIZE);
-	futex_ptr = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+	futex_ptr = mmap(NULL, mem_size * 2, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
 	if (futex_ptr == MAP_FAILED)
 		ksft_exit_fail_msg("mmap() for %d bytes failed\n", mem_size);
 
+	/* Create an invalid memory region for the "Memory out of range" test */
+	mprotect(futex_ptr + mem_size, mem_size, PROT_NONE);
+
 	futex_numa = futex_ptr;
 
 	ksft_print_msg("Regular test\n");
@@ -192,6 +195,9 @@ int main(int argc, char *argv[])
 	ksft_print_msg("Mis-aligned futex\n");
 	test_futex(futex_ptr + mem_size - 4, 22);
 
+	ksft_print_msg("Memory out of range\n");
+	test_futex(futex_ptr + mem_size, 14);
+
 	futex_numa->numa = FUTEX_NO_NODE;
 	mprotect(futex_ptr, mem_size, PROT_READ);
 	ksft_print_msg("Memory, RO\n");
-- 
2.51.0

Re: [PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

[Waiman Long]

On 9/1/25 4:33 PM, André Almeida wrote:
> Instead of just checking if the syscall failed as expected, check as
> well what is the error code returned, to check if it's match the
> expectation and it's failing in the correct error path inside the
> kernel.
>
> Signed-off-by: André Almeida <andrealmeid@igalia.com>
> ---
> This patch is aimed for 6.18
> ---
>   .../futex/functional/futex_numa_mpol.c        | 36 +++++++++++--------
>   1 file changed, 21 insertions(+), 15 deletions(-)
>
> diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> index 802c15c82190..c84441751235 100644
> --- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> +++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> @@ -77,7 +77,7 @@ static void join_max_threads(void)
>   	}
>   }
>   
> -static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flags)
> +static void __test_futex(void *futex_ptr, int err_value, unsigned int futex_flags)
>   {
>   	int to_wake, ret, i, need_exit = 0;
>   
> @@ -88,11 +88,17 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
>   
>   	do {
>   		ret = futex2_wake(futex_ptr, to_wake, futex_flags);
> -		if (must_fail) {
> -			if (ret < 0)
> -				break;
> -			ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
> -					   to_wake, futex_flags);
> +
> +		if (err_value) {
> +			if (ret >= 0)
> +				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
> +						   to_wake, futex_flags);
> +
> +			if (errno != err_value)
> +				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) expected error was %d, but returned %d (%s)\n",
> +						   to_wake, futex_flags, err_value, errno, strerror(errno));
> +
> +			break;

If (ret >= 0), the 2nd (errno != err_value) failure message will likely 
be printed too. Should we use "else if" so that only one error message 
will be printed?


>   		}
>   		if (ret < 0) {
>   			ksft_exit_fail_msg("Failed futex2_wake(%d, 0x%x): %m\n",
> @@ -106,12 +112,12 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
>   	join_max_threads();
>   
>   	for (i = 0; i < MAX_THREADS; i++) {
> -		if (must_fail && thread_args[i].result != -1) {
> +		if (err_value && thread_args[i].result != -1) {
>   			ksft_print_msg("Thread %d should fail but succeeded (%d)\n",
>   				       i, thread_args[i].result);
>   			need_exit = 1;
>   		}
> -		if (!must_fail && thread_args[i].result != 0) {
> +		if (!err_value && thread_args[i].result != 0) {
>   			ksft_print_msg("Thread %d failed (%d)\n", i, thread_args[i].result);
>   			need_exit = 1;
>   		}
> @@ -120,14 +126,14 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
>   		ksft_exit_fail_msg("Aborting due to earlier errors.\n");
>   }
>   
> -static void test_futex(void *futex_ptr, int must_fail)
> +static void test_futex(void *futex_ptr, int err_value)
>   {
> -	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
> +	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
>   }
>   
> -static void test_futex_mpol(void *futex_ptr, int must_fail)
> +static void test_futex_mpol(void *futex_ptr, int err_value)
>   {
> -	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
> +	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
>   }
>   
>   static void usage(char *prog)
> @@ -184,16 +190,16 @@ int main(int argc, char *argv[])
>   
>   	/* FUTEX2_NUMA futex must be 8-byte aligned */
>   	ksft_print_msg("Mis-aligned futex\n");
> -	test_futex(futex_ptr + mem_size - 4, 1);
> +	test_futex(futex_ptr + mem_size - 4, 22);
>   
>   	futex_numa->numa = FUTEX_NO_NODE;
>   	mprotect(futex_ptr, mem_size, PROT_READ);
>   	ksft_print_msg("Memory, RO\n");
> -	test_futex(futex_ptr, 1);
> +	test_futex(futex_ptr, 14);
>   
>   	mprotect(futex_ptr, mem_size, PROT_NONE);
>   	ksft_print_msg("Memory, no access\n");
> -	test_futex(futex_ptr, 1);
> +	test_futex(futex_ptr, 14);
>   
>   	mprotect(futex_ptr, mem_size, PROT_READ | PROT_WRITE);
>   	ksft_print_msg("Memory back to RW\n");

I believe it is better to use the error number mnemonic (EINVAL & 
EFAULT) instead of 22 and 14 as argument to make the code easier to read.

Cheers,
Longman

Re: [PATCH 2/2] selftest/futex: Reintroduce "Memory out of range" numa_mpol's subtest

[Waiman Long]

On 9/1/25 4:33 PM, André Almeida wrote:
> Commit d8e2f919997 ("selftests/futex: Fix some futex_numa_mpol
> subtests") removed the "Memory out of range" subtest due to it being
> dependent on the memory layout of the test process having an invalid
> memory address just after the `*futex_ptr` allocated memory.
>
> Reintroduce this test and make it deterministic, by allocation two
> memory pages and marking the second one with PROT_NONE.
>
> Signed-off-by: André Almeida <andrealmeid@igalia.com>
> ---
> This patch is aimed for 6.18
> ---
>   .../testing/selftests/futex/functional/futex_numa_mpol.c  | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> index c84441751235..e4b840184b1d 100644
> --- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> +++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
> @@ -174,10 +174,13 @@ int main(int argc, char *argv[])
>   	ksft_set_plan(1);
>   
>   	mem_size = sysconf(_SC_PAGE_SIZE);
> -	futex_ptr = mmap(NULL, mem_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
> +	futex_ptr = mmap(NULL, mem_size * 2, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
>   	if (futex_ptr == MAP_FAILED)
>   		ksft_exit_fail_msg("mmap() for %d bytes failed\n", mem_size);
>   
> +	/* Create an invalid memory region for the "Memory out of range" test */
> +	mprotect(futex_ptr + mem_size, mem_size, PROT_NONE);
> +
>   	futex_numa = futex_ptr;
>   
>   	ksft_print_msg("Regular test\n");
> @@ -192,6 +195,9 @@ int main(int argc, char *argv[])
>   	ksft_print_msg("Mis-aligned futex\n");
>   	test_futex(futex_ptr + mem_size - 4, 22);
>   
> +	ksft_print_msg("Memory out of range\n");
> +	test_futex(futex_ptr + mem_size, 14);
> +
>   	futex_numa->numa = FUTEX_NO_NODE;
>   	mprotect(futex_ptr, mem_size, PROT_READ);
>   	ksft_print_msg("Memory, RO\n");
Reviewed-by: Waiman Long <longman@redhat.com>

Re: [PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

[André Almeida]

Hi Waiman,

Thanks for the feedback!

Em 03/09/2025 14:53, Waiman Long escreveu:
> On 9/1/25 4:33 PM, André Almeida wrote:
>> Instead of just checking if the syscall failed as expected, check as
>> well what is the error code returned, to check if it's match the
>> expectation and it's failing in the correct error path inside the
>> kernel.
>>
>> Signed-off-by: André Almeida <andrealmeid@igalia.com>
>> ---
>> This patch is aimed for 6.18
>> ---
>>   .../futex/functional/futex_numa_mpol.c        | 36 +++++++++++--------
>>   1 file changed, 21 insertions(+), 15 deletions(-)
>>
>> diff --git a/tools/testing/selftests/futex/functional/ 
>> futex_numa_mpol.c b/tools/testing/selftests/futex/functional/ 
>> futex_numa_mpol.c
>> index 802c15c82190..c84441751235 100644
>> --- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
>> +++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
>> @@ -77,7 +77,7 @@ static void join_max_threads(void)
>>       }
>>   }
>> -static void __test_futex(void *futex_ptr, int must_fail, unsigned int 
>> futex_flags)
>> +static void __test_futex(void *futex_ptr, int err_value, unsigned int 
>> futex_flags)
>>   {
>>       int to_wake, ret, i, need_exit = 0;
>> @@ -88,11 +88,17 @@ static void __test_futex(void *futex_ptr, int 
>> must_fail, unsigned int futex_flag
>>       do {
>>           ret = futex2_wake(futex_ptr, to_wake, futex_flags);
>> -        if (must_fail) {
>> -            if (ret < 0)
>> -                break;
>> -            ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, 
>> but didn't\n",
>> -                       to_wake, futex_flags);
>> +
>> +        if (err_value) {
>> +            if (ret >= 0)
>> +                ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should 
>> fail, but didn't\n",
>> +                           to_wake, futex_flags);
>> +
>> +            if (errno != err_value)
>> +                ksft_exit_fail_msg("futex2_wake(%d, 0x%x) expected 
>> error was %d, but returned %d (%s)\n",
>> +                           to_wake, futex_flags, err_value, errno, 
>> strerror(errno));
>> +
>> +            break;
> 
> If (ret >= 0), the 2nd (errno != err_value) failure message will likely 
> be printed too. Should we use "else if" so that only one error message 
> will be printed?
> 
> 

ksft_exit_fail_msg() calls exit(), so the code will exit before 
executing the second failure message.

If this was a  ksft_test_result_error() call, then the message would be 
printed twice.

>>           }
>>           if (ret < 0) {
>>               ksft_exit_fail_msg("Failed futex2_wake(%d, 0x%x): %m\n",
>> @@ -106,12 +112,12 @@ static void __test_futex(void *futex_ptr, int 
>> must_fail, unsigned int futex_flag
>>       join_max_threads();
>>       for (i = 0; i < MAX_THREADS; i++) {
>> -        if (must_fail && thread_args[i].result != -1) {
>> +        if (err_value && thread_args[i].result != -1) {
>>               ksft_print_msg("Thread %d should fail but succeeded 
>> (%d)\n",
>>                          i, thread_args[i].result);
>>               need_exit = 1;
>>           }
>> -        if (!must_fail && thread_args[i].result != 0) {
>> +        if (!err_value && thread_args[i].result != 0) {
>>               ksft_print_msg("Thread %d failed (%d)\n", i, 
>> thread_args[i].result);
>>               need_exit = 1;
>>           }
>> @@ -120,14 +126,14 @@ static void __test_futex(void *futex_ptr, int 
>> must_fail, unsigned int futex_flag
>>           ksft_exit_fail_msg("Aborting due to earlier errors.\n");
>>   }
>> -static void test_futex(void *futex_ptr, int must_fail)
>> +static void test_futex(void *futex_ptr, int err_value)
>>   {
>> -    __test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | 
>> FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
>> +    __test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | 
>> FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
>>   }
>> -static void test_futex_mpol(void *futex_ptr, int must_fail)
>> +static void test_futex_mpol(void *futex_ptr, int err_value)
>>   {
>> -    __test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | 
>> FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
>> +    __test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | 
>> FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
>>   }
>>   static void usage(char *prog)
>> @@ -184,16 +190,16 @@ int main(int argc, char *argv[])
>>       /* FUTEX2_NUMA futex must be 8-byte aligned */
>>       ksft_print_msg("Mis-aligned futex\n");
>> -    test_futex(futex_ptr + mem_size - 4, 1);
>> +    test_futex(futex_ptr + mem_size - 4, 22);
>>       futex_numa->numa = FUTEX_NO_NODE;
>>       mprotect(futex_ptr, mem_size, PROT_READ);
>>       ksft_print_msg("Memory, RO\n");
>> -    test_futex(futex_ptr, 1);
>> +    test_futex(futex_ptr, 14);
>>       mprotect(futex_ptr, mem_size, PROT_NONE);
>>       ksft_print_msg("Memory, no access\n");
>> -    test_futex(futex_ptr, 1);
>> +    test_futex(futex_ptr, 14);
>>       mprotect(futex_ptr, mem_size, PROT_READ | PROT_WRITE);
>>       ksft_print_msg("Memory back to RW\n");
> 
> I believe it is better to use the error number mnemonic (EINVAL & 
> EFAULT) instead of 22 and 14 as argument to make the code easier to read.
> 

Good call, applied.

Thanks!
André

> Cheers,
> Longman
> 

Re: [PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

[Waiman Long]

On 9/4/25 11:23 AM, André Almeida wrote:
> Hi Waiman,
>
> Thanks for the feedback!
>
> Em 03/09/2025 14:53, Waiman Long escreveu:
>> On 9/1/25 4:33 PM, André Almeida wrote:
>>> Instead of just checking if the syscall failed as expected, check as
>>> well what is the error code returned, to check if it's match the
>>> expectation and it's failing in the correct error path inside the
>>> kernel.
>>>
>>> Signed-off-by: André Almeida <andrealmeid@igalia.com>
>>> ---
>>> This patch is aimed for 6.18
>>> ---
>>>   .../futex/functional/futex_numa_mpol.c        | 36 
>>> +++++++++++--------
>>>   1 file changed, 21 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/tools/testing/selftests/futex/functional/ 
>>> futex_numa_mpol.c b/tools/testing/selftests/futex/functional/ 
>>> futex_numa_mpol.c
>>> index 802c15c82190..c84441751235 100644
>>> --- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
>>> +++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
>>> @@ -77,7 +77,7 @@ static void join_max_threads(void)
>>>       }
>>>   }
>>> -static void __test_futex(void *futex_ptr, int must_fail, unsigned 
>>> int futex_flags)
>>> +static void __test_futex(void *futex_ptr, int err_value, unsigned 
>>> int futex_flags)
>>>   {
>>>       int to_wake, ret, i, need_exit = 0;
>>> @@ -88,11 +88,17 @@ static void __test_futex(void *futex_ptr, int 
>>> must_fail, unsigned int futex_flag
>>>       do {
>>>           ret = futex2_wake(futex_ptr, to_wake, futex_flags);
>>> -        if (must_fail) {
>>> -            if (ret < 0)
>>> -                break;
>>> -            ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, 
>>> but didn't\n",
>>> -                       to_wake, futex_flags);
>>> +
>>> +        if (err_value) {
>>> +            if (ret >= 0)
>>> +                ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should 
>>> fail, but didn't\n",
>>> +                           to_wake, futex_flags);
>>> +
>>> +            if (errno != err_value)
>>> +                ksft_exit_fail_msg("futex2_wake(%d, 0x%x) expected 
>>> error was %d, but returned %d (%s)\n",
>>> +                           to_wake, futex_flags, err_value, errno, 
>>> strerror(errno));
>>> +
>>> +            break;
>>
>> If (ret >= 0), the 2nd (errno != err_value) failure message will 
>> likely be printed too. Should we use "else if" so that only one error 
>> message will be printed?
>>
>>
>
> ksft_exit_fail_msg() calls exit(), so the code will exit before 
> executing the second failure message.
>
> If this was a  ksft_test_result_error() call, then the message would 
> be printed twice.

I didn't realize that. Thanks for letting me know. In that case, the 
code should be OK.

Cheers,
Longman