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From: Christian Brauner <christian.brauner@ubuntu.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org, libc-alpha@sourceware.org,
	alistair23@gmail.com, ebiederm@xmission.com, arnd@arndb.de,
	dalias@libc.org, torvalds@linux-foundation.org,
	adhemerval.zanella@linaro.org, fweimer@redhat.com,
	palmer@sifive.com, macro@wdc.com, zongbox@gmail.com,
	akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
	hpa@zytor.com
Subject: Re: [PATCH v2 1/1] waitid: Add support for waiting for the current process group
Date: Wed, 14 Aug 2019 17:30:23 +0200
Message-ID: <20190814153023.ruf6m3kxiskhefsv@wittgenstein> (raw)
In-Reply-To: <20190814152712.GE11595@redhat.com>

On Wed, Aug 14, 2019 at 05:27:12PM +0200, Oleg Nesterov wrote:
> On 08/14, Christian Brauner wrote:
> >
> > On Wed, Aug 14, 2019 at 04:19:57PM +0200, Oleg Nesterov wrote:
> > > On 08/14, Christian Brauner wrote:
> > > >
> > > > +static struct pid *find_get_pgrp(pid_t nr)
> > > > +{
> > > > +	struct pid *pid;
> > > > +
> > > > +	if (nr)
> > > > +		return find_get_pid(nr);
> > > > +
> > > > +	rcu_read_lock();
> > > > +	pid = get_pid(task_pgrp(current));
> > > > +	rcu_read_unlock();
> > > > +
> > > > +	return pid;
> > > > +}
> > >
> > > I can't say I like this helper... even its name doesn't look good to me.
> >
> > Well, naming scheme obviously stolen from find_get_pid(). Not sure if
> > that doesn't look good as well. ;)
> 
> find_get_pid() actually tries to find a pid. The helper above does "find"
> or "use current" depending on nr != 0.
> 
> > > I forgot that we already have get_task_pid() when I replied to the previous
> > > version... How about
> > >
> > > 	case P_PGID:
> > >
> > > 		if (upid)
> > > 			pid = find_get_pid(upid);
> > > 		else
> > > 			pid = get_task_pid(current, PIDTYPE_PGID);
> > >
> > > ?
> >
> > Hmyeah, that works but wouldn't it still be nicer to simply have:
> >
> > static struct pid *get_pgrp(pid_t nr)
> > {
> > 	if (nr)
> > 		return find_get_pid(nr);
> >
> > 	return get_task_pid(current, PIDTYPE_PGID);
> > }
> 
> Who else can ever use it?
> 
> It saves 4 lines in kernel_waitid() but adds 7 lines outside, and you
> need another ^] to see these lines if you try to understand what
> PIDTYPE_PGID actually does. IOW, I think this helper will make waitid
> less readable for no reason.
> 
> 
> Christian, I try to never argue when it comes to cosmetic issues, and
> in this case I won't insist too.

Yeah, I know. I'm not insisisting either. We can do your thing since you
do after all seem to care at least a tiny bit. ;)

Christian

  reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAKmqyKMJPQAOKn11xepzAwXOd4e9dU0Cyz=A0T-uMEgUp5yJjA@mail.gmail.com>
2019-08-14 11:38 ` [PATCH v1 0/1] waitid: process group enhancement christian.brauner
2019-08-14 11:38   ` [PATCH v1 1/1] waitid: Add support for waiting for the current process group christian.brauner
2019-08-14 12:29     ` Oleg Nesterov
2019-08-14 12:45       ` Christian Brauner
2019-08-14 12:50         ` Oleg Nesterov
2019-08-14 12:53           ` Christian Brauner
2019-08-14 13:07 ` [PATCH v2 0/1] waitid: process group enhancement Christian Brauner
2019-08-14 13:07   ` [PATCH v2 1/1] waitid: Add support for waiting for the current process group Christian Brauner
2019-08-14 14:19     ` Oleg Nesterov
2019-08-14 14:35       ` Christian Brauner
2019-08-14 15:27         ` Oleg Nesterov
2019-08-14 15:30           ` Christian Brauner [this message]
2019-08-14 15:43 ` [PATCH v3 0/1] waitid: process group enhancement Christian Brauner
2019-08-14 15:44   ` [PATCH v3 1/1] waitid: Add support for waiting for the current process group Christian Brauner
2019-08-14 16:09     ` Oleg Nesterov
2019-08-14 16:15       ` Christian Brauner
2019-08-14 16:34         ` Christian Brauner
2019-08-14 16:55           ` Rich Felker
2019-08-14 17:02             ` Christian Brauner
2019-08-14 17:06             ` Linus Torvalds
2019-08-14 18:00               ` Rich Felker
2019-08-14 20:50       ` Christian Brauner
2019-08-14 15:58   ` [PATCH v3 0/1] waitid: process group enhancement Rich Felker
2019-08-14 16:13     ` Christian Brauner

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