linux-kernel - Re: [PATCH net-next 1/2] connector/cn_proc: Handle threads for proc connector

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Message-ID: <20240920184430.GB20847@redhat.com>
Date: Fri, 20 Sep 2024 20:44:31 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
Cc: "davem@...emloft.net" <davem@...emloft.net>,
	Liam Howlett <liam.howlett@...cle.com>,
	"edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"axboe@...nel.dk" <axboe@...nel.dk>,
	"brauner@...nel.org" <brauner@...nel.org>,
	"mhocko@...e.com" <mhocko@...e.com>,
	"alexjlzheng@...cent.com" <alexjlzheng@...cent.com>,
	"willy@...radead.org" <willy@...radead.org>,
	Michael Christie <michael.christie@...cle.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"shuah@...nel.org" <shuah@...nel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
	Pei Li <peili.io@...cle.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH net-next 1/2] connector/cn_proc: Handle threads for proc
 connector

On 09/20, Anjali Kulkarni wrote:
>
> > On Sep 20, 2024, at 4:00 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> >
> > I don't think you can use task_struct->exit_code. If this task is ptraced,
> > it can be changed/cleared in, say, ptrace_stop() after PROC_CN_MCAST_NOTIFY.
> >
>
> Thank you, that’s a good point! However, the use case of ptrace, which I assume
> is for mostly debug and tracing, is exclusive of the use case I am using it for

Well. I don't understand your use-case. Or any other use-case for drivers/connector/
that I know nothing about. But this is irrelevant.

The new PROC_CN_MCAST_NOTIFY functionality you propose should work regardless of
whether this task is ptraced or not. But it doesn't because the usage of ->exit_code
in your patch conflicts with the current usage of this field.

So, NACK, sorry.

Oleg.