linux-kernel - Re: [PATCH v4 2/2] selftests: Add a test mangling with uc

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Message-ID: <01e41c46-255a-419a-9b72-485a2798205f@arm.com>
Date: Tue, 23 Jul 2024 10:00:09 +0530
From: Dev Jain <dev.jain@....com>
To: Shuah Khan <skhan@...uxfoundation.org>, Oleg Nesterov <oleg@...hat.com>
Cc: shuah@...nel.org, mingo@...nel.org, tglx@...utronix.de,
 mark.rutland@....com, ryan.roberts@....com, broonie@...nel.org,
 suzuki.poulose@....com, Anshuman.Khandual@....com,
 DeepakKumar.Mishra@....com, aneesh.kumar@...nel.org,
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] selftests: Add a test mangling with uc_sigmask


On 7/22/24 20:28, Shuah Khan wrote:
> On 7/15/24 05:49, Dev Jain wrote:
>>
>> On 6/30/24 20:48, Oleg Nesterov wrote:
>>> I see nothing wrong, but perhaps this test can be simplified?
>>> Feel free to ignore.
>>>
>>> Say,
>>>
>>> On 06/27, Dev Jain wrote:
>>>> +void handler_usr(int signo, siginfo_t *info, void *uc)
>>>> +{
>>>> +    int ret;
>>>> +
>>>> +    /*
>>>> +     * Break out of infinite recursion caused by raise(SIGUSR1) 
>>>> invoked
>>>> +     * from inside the handler
>>>> +     */
>>>> +    ++cnt;
>>>> +    if (cnt > 1)
>>>> +        return;
>>>> +
>>>> +    ksft_print_msg("In handler_usr\n");
>
> This message isn't very useful. Why do you need this message?


There isn't any specific use; I am just showing the progress

of the test. If you think this is just waste output....

>
>>>> +
>>>> +    /* SEGV blocked during handler execution, delivered on return */
>>>> +    if (raise(SIGSEGV))
>>>> +        ksft_exit_fail_perror("raise");>>> +
>>>> +    ksft_print_msg("SEGV bypassed successfully\n");
>>> You could simply do sigprocmask(SIG_SETMASK, NULL, &oldset) and 
>>> check if
>>> SIGSEGV is blocked in oldset. SIG_SETMASK has no effect if newset == 
>>> NULL.
>>>
>>
>> IMHO, isn't raising the signal, and the process not terminating, a 
>> stricter test? I have already included your described approach in
>> the last testcase; so, the test includes both ways: raising the
>> signal -> process not terminating, and checking blockage with 
>> sigprocmask().
>
> thanks,
> -- Shuah
>