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 16:35:46 +0200 [thread overview]
Message-ID: <20190814143545.tu6xfp2mxmnzwkx4@wittgenstein> (raw)
In-Reply-To: <20190814141956.GC11595@redhat.com>
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. ;)
>
> 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);
}
That allows us to have all cases equivalent with a single call to a
function without any if-elses.
Imho, this becomes especially nice when considering that P_PIDFD goes on
top of that:
switch (which) {
case P_ALL:
type = PIDTYPE_MAX;
break;
case P_PID:
type = PIDTYPE_PID;
if (upid <= 0)
return -EINVAL;
pid = find_get_pid(upid);
break;
case P_PGID:
type = PIDTYPE_PGID;
if (upid < 0)
return -EINVAL;
pid = find_get_pgrp(upid);
break;
case P_PIDFD:
type = PIDTYPE_PID;
if (upid < 0)
return -EINVAL;
pid = pidfd_get_pid(upid);
if (IS_ERR(pid))
return PTR_ERR(pid);
break;
default:
return -EINVAL;
}
Christian
next prev parent reply other threads:[~2019-08-14 14:35 UTC|newest]
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 [this message]
2019-08-14 15:27 ` Oleg Nesterov
2019-08-14 15:30 ` Christian Brauner
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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