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Date:   Mon, 17 Apr 2023 20:46:51 +0200
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Subject: Re: Checking for support of ptrace(PTRACE_SEIZE,...) on older kernels
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To:     Oleg Nesterov <oleg@redhat.com>
Cc:     Sergei Zhirikov <sfzhi@yahoo.com>, linux-man@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>
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 <997950238.3486335.1681414225118@mail.yahoo.com>
 <0d95a96b-dd49-db45-ab3c-1d9cee51381d@gmail.com>
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From:   Alejandro Colomar <alx.manpages@gmail.com>
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From: Alejandro Colomar <alx.manpages@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Sergei Zhirikov <sfzhi@yahoo.com>, linux-man@vger.kernel.org,
 LKML <linux-kernel@vger.kernel.org>
Message-ID: <88991b38-26f5-e060-3a29-5f17c5fc85df@gmail.com>
Subject: Re: Checking for support of ptrace(PTRACE_SEIZE,...) on older kernels
References: <997950238.3486335.1681414225118.ref@mail.yahoo.com>
 <997950238.3486335.1681414225118@mail.yahoo.com>
 <0d95a96b-dd49-db45-ab3c-1d9cee51381d@gmail.com>
 <20230417115009.GA906@redhat.com>
In-Reply-To: <20230417115009.GA906@redhat.com>

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Hi Oleg,

On 4/17/23 13:50, Oleg Nesterov wrote:
> Well, from https://man7.org/linux/man-pages/man2/ptrace.2.html
>=20
>        ESRCH  The specified process does not exist, or is not currently=

>               being traced by the caller, or is not stopped (for
>               requests that require a stopped tracee).
>=20
> so if the kernel doesn't support PTRACE_SEIZE then ptrace(PTRACE_SEIZE)=

> should fail with -ESRCH as documented.
>=20
> Perhaps this part
>=20
>        EIO    request is invalid, or ...
>=20
> can be improvef a bit to explain that this happens if the target is alr=
eady
> traced by us and stopped.

I'm not sure if it's necessary.  When several errors happen at the same t=
ime,
there's usually no documentation about which takes precedence, with few
exceptions.  Knowing it's intentional, I'm content.

Thanks,

Alex

--=20
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5

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