Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 28 Nov 2018 14:13:48 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     "Dmitry V. Levin" <ldv@altlinux.org>
Cc:     Elvira Khabirova <lineprinter@altlinux.org>,
        Eugene Syromyatnikov <esyr@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Andy Lutomirski <luto@kernel.org>,
        Ingo Molnar <mingo@redhat.com>, linux-api@vger.kernel.org,
        linux-kernel@vger.kernel.org, strace-devel@lists.strace.io
Subject: Re: [RFC PATCH RESEND v3 3/3] ptrace: add PTRACE_EVENT_SECCOMP
 support to PTRACE_GET_SYSCALL_INFO
Message-ID: <20181128131347.GB30395@redhat.com>
References: <20181125022150.46258a20@akathisia>
 <20181125022340.5703400f@akathisia>
 <20181126143524.GB1660@redhat.com>
 <20181127040732.1c9f7965@akathisia>
 <20181127123116.GA13284@redhat.com>
 <20181127232753.GA18755@altlinux.org>
 <20181128123545.GA30395@redhat.com>
 <20181128124411.GA28206@altlinux.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181128124411.GA28206@altlinux.org>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 11/28, Dmitry V. Levin wrote:
>
> What about PTRACE_GETSIGINFO?  Can it also be done lockless because
> ptrace_check_attach() has already called ptrace_freeze_traced()?

Yes, only PTRACE_INTERRUPT needs lock_task_sighand() and it can actually
fail because the tracee is not necessarily stopped.

Oleg.