linux-kernel - Re: [PATCH 2/4] signals: send_signal: use si_fromuser() to detect from_ancestor

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Date:	Mon, 5 Oct 2009 19:34:01 -0700
From:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Daniel Lezcano <dlezcano@...ibm.com>,
	Sukadev Bhattiprolu <sukadev@...ibm.com>,
	Linux Containers <containers@...ts.osdl.org>,
	roland@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] signals: send_signal: use si_fromuser() to detect
	from_ancestor_ns

Oleg Nesterov [oleg@...hat.com] wrote:
| On 10/05, Sukadev Bhattiprolu wrote:
| >
| > Oleg Nesterov [oleg@...hat.com] wrote:
| > | Sorry for confusion.
| > |
| > | > But sure, we could use force_sig_info() in caller.
| > |
| > | Yes, because this makes the code more explicit imho. And we can avoid
| > | the further complicatiions in send_signal() path.
| >
| > Although, one small drawback would be the different behavior for the
| > SIGKILL in load_aout_binary() to the container-init itself calling:
| >
| > 	kill(getpid(), SIGKILL);
| 
| could you clarify? load_aout_binary(), like other ->load_binary()
| methods does send_sig(SIGKILL, current, 0) ?

Yes sorry for being cryptic.

If we use force_sig_info() in ->load_binary() methods for the SIGKILL,
they will, correctly, kill the container-init.

But if the container-init itself calls kill(getpid(), SIGKILL), the
container-init will not be killed.

I was just pointing out the small difference in behavior for the
same signal (when we use force_sig_info()).

Thanks for fixing the bug.

Sukadev
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