linux-kernel - RE: [PATCH] signal: trace_signal_deliver when signal_group

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Date:   Mon, 22 Apr 2019 02:37:21 +0000
From:   weizhenliang <weizhenliang@...wei.com>
To:     Oleg Nesterov <oleg@...hat.com>
CC:     "ebiederm@...ssion.com" <ebiederm@...ssion.com>,
        "colona@...sta.com" <colona@...sta.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "christian@...uner.io" <christian@...uner.io>,
        "arnd@...db.de" <arnd@...db.de>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "deepa.kernel@...il.com" <deepa.kernel@...il.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: RE: [PATCH] signal: trace_signal_deliver when signal_group_exit

On 04/20, Oleg Nesterov wrote:
>On 04/20, Zhenliang Wei wrote:
>>
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -2441,6 +2441,8 @@ bool get_signal(struct ksignal *ksig)
>>  	if (signal_group_exit(signal)) {
>>  		ksig->info.si_signo = signr = SIGKILL;
>>  		sigdelset(&current->pending.signal, SIGKILL);
>> +		trace_signal_deliver(signr, &ksig->info,
>> +				&sighand->action[signr - 1]);
>
>Well, in this case ksig->info is not fully initialized for TP_STORE_SIGINFO() which reads si_errno/si_code...
>
>How about
>
>		trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, SIG_DFL)
>
>?
>
>We know that action[SIGKILL] must be SIG_DFL.
>
>And SEND_SIG_NOINFO matches the fact that SIGKILL doesn't have any info,
>collect_signal() sets SI_USER and clears si_errno in this case.
>
>Oleg.

Thank you for your review, I agree with your suggestion, and I will recommit the patch later.

Zhenliang Wei.