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From: Joel Fernandes <joel@joelfernandes.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Christian Brauner <christian@brauner.io>,
	linux-kernel@vger.kernel.org, luto@amacapital.net,
	rostedt@goodmis.org, dancol@google.com, sspatil@google.com,
	jannh@google.com, surenb@google.com, timmurray@google.com,
	Jonathan Kowalski <bl0pbl33p@gmail.com>,
	torvalds@linux-foundation.org, kernel-team@android.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>, Jann Horn <jann@thejh.net>,
	linux-kselftest@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Serge Hallyn <serge@hallyn.com>, Shuah Khan <shuah@kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>, Thomas Gleixner <tgl>
Subject: Re: [PATCH v1 1/2] Add polling support to pidfd
Date: Mon, 29 Apr 2019 10:07:43 -0400	[thread overview]
Message-ID: <20190429140743.GB173743@google.com> (raw)
In-Reply-To: <20190429140245.GB233442@google.com>

On Mon, Apr 29, 2019 at 10:02:45AM -0400, Joel Fernandes wrote:
> On Sun, Apr 28, 2019 at 06:24:06PM +0200, Oleg Nesterov wrote:
[snip]
> > > > +{
> > > > +	struct pid *pid;
> > > > +
> > > > +	lockdep_assert_held(&tasklist_lock);
> > > > +
> > > > +	pid = get_task_pid(task, PIDTYPE_PID);
> > > > +	wake_up_all(&pid->wait_pidfd);
> > > > +	put_pid(pid);
> > 
> > Why get/put?
> 
> Yes, pid_task() should do it. Will update it. Thanks!

I spoke too soon. We need the task's pid of type PIDTYPE_PID. How else can we
get it? This does an atomic_inc on the pid->count, so we need to put_pid()
after we are done with it. Did I miss something?

thanks,

 - Joel

 

WARNING: multiple messages have this Message-ID (diff)
From: joel at joelfernandes.org (Joel Fernandes)
Subject: [PATCH v1 1/2] Add polling support to pidfd
Date: Mon, 29 Apr 2019 10:07:43 -0400	[thread overview]
Message-ID: <20190429140743.GB173743@google.com> (raw)
In-Reply-To: <20190429140245.GB233442@google.com>

On Mon, Apr 29, 2019 at 10:02:45AM -0400, Joel Fernandes wrote:
> On Sun, Apr 28, 2019 at 06:24:06PM +0200, Oleg Nesterov wrote:
[snip]
> > > > +{
> > > > +	struct pid *pid;
> > > > +
> > > > +	lockdep_assert_held(&tasklist_lock);
> > > > +
> > > > +	pid = get_task_pid(task, PIDTYPE_PID);
> > > > +	wake_up_all(&pid->wait_pidfd);
> > > > +	put_pid(pid);
> > 
> > Why get/put?
> 
> Yes, pid_task() should do it. Will update it. Thanks!

I spoke too soon. We need the task's pid of type PIDTYPE_PID. How else can we
get it? This does an atomic_inc on the pid->count, so we need to put_pid()
after we are done with it. Did I miss something?

thanks,

 - Joel

 

WARNING: multiple messages have this Message-ID (diff)
From: joel@joelfernandes.org (Joel Fernandes)
Subject: [PATCH v1 1/2] Add polling support to pidfd
Date: Mon, 29 Apr 2019 10:07:43 -0400	[thread overview]
Message-ID: <20190429140743.GB173743@google.com> (raw)
Message-ID: <20190429140743.HcI12Re6p2r7NQqRblh3WVz3p6UNEGbjQ2YdmdlZB0E@z> (raw)
In-Reply-To: <20190429140245.GB233442@google.com>

On Mon, Apr 29, 2019@10:02:45AM -0400, Joel Fernandes wrote:
> On Sun, Apr 28, 2019@06:24:06PM +0200, Oleg Nesterov wrote:
[snip]
> > > > +{
> > > > +	struct pid *pid;
> > > > +
> > > > +	lockdep_assert_held(&tasklist_lock);
> > > > +
> > > > +	pid = get_task_pid(task, PIDTYPE_PID);
> > > > +	wake_up_all(&pid->wait_pidfd);
> > > > +	put_pid(pid);
> > 
> > Why get/put?
> 
> Yes, pid_task() should do it. Will update it. Thanks!

I spoke too soon. We need the task's pid of type PIDTYPE_PID. How else can we
get it? This does an atomic_inc on the pid->count, so we need to put_pid()
after we are done with it. Did I miss something?

thanks,

 - Joel

 

WARNING: multiple messages have this Message-ID (diff)
From: Joel Fernandes <joel@joelfernandes.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Christian Brauner <christian@brauner.io>,
	linux-kernel@vger.kernel.org, luto@amacapital.net,
	rostedt@goodmis.org, dancol@google.com, sspatil@google.com,
	jannh@google.com, surenb@google.com, timmurray@google.com,
	Jonathan Kowalski <bl0pbl33p@gmail.com>,
	torvalds@linux-foundation.org, kernel-team@android.com,
	Andrew Morton <akpm@linux-foundation.org>,
	Arnd Bergmann <arnd@arndb.de>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>, Jann Horn <jann@thejh.net>,
	linux-kselftest@vger.kernel.org, Michal Hocko <mhocko@suse.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Serge Hallyn <serge@hallyn.com>, Shuah Khan <shuah@kernel.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tycho Andersen <tycho@tycho.ws>,
	viro@zeniv.linux.org.uk, linux-api@vger.kernel.org
Subject: Re: [PATCH v1 1/2] Add polling support to pidfd
Date: Mon, 29 Apr 2019 10:07:43 -0400	[thread overview]
Message-ID: <20190429140743.GB173743@google.com> (raw)
In-Reply-To: <20190429140245.GB233442@google.com>

On Mon, Apr 29, 2019 at 10:02:45AM -0400, Joel Fernandes wrote:
> On Sun, Apr 28, 2019 at 06:24:06PM +0200, Oleg Nesterov wrote:
[snip]
> > > > +{
> > > > +	struct pid *pid;
> > > > +
> > > > +	lockdep_assert_held(&tasklist_lock);
> > > > +
> > > > +	pid = get_task_pid(task, PIDTYPE_PID);
> > > > +	wake_up_all(&pid->wait_pidfd);
> > > > +	put_pid(pid);
> > 
> > Why get/put?
> 
> Yes, pid_task() should do it. Will update it. Thanks!

I spoke too soon. We need the task's pid of type PIDTYPE_PID. How else can we
get it? This does an atomic_inc on the pid->count, so we need to put_pid()
after we are done with it. Did I miss something?

thanks,

 - Joel

 

  reply	other threads:[~2019-04-29 14:07 UTC|newest]

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-25 19:00 [PATCH v1 1/2] Add polling support to pidfd joel
2019-04-25 19:00 ` Joel Fernandes (Google)
2019-04-25 19:00 ` Joel Fernandes (Google)
2019-04-25 19:00 ` [PATCH v1 2/2] Add selftests for pidfd polling joel
2019-04-25 19:00   ` Joel Fernandes (Google)
2019-04-25 19:00   ` Joel Fernandes (Google)
2019-04-25 20:00   ` tycho
2019-04-25 20:00     ` Tycho Andersen
2019-04-25 20:00     ` Tycho Andersen
2019-04-26 13:47     ` joel
2019-04-26 13:47       ` Joel Fernandes
2019-04-26 13:47       ` Joel Fernandes
2019-04-25 21:29   ` christian
2019-04-25 21:29     ` Christian Brauner
2019-04-25 21:29     ` Christian Brauner
2019-04-25 22:07     ` dancol
2019-04-25 22:07       ` Daniel Colascione
2019-04-25 22:07       ` Daniel Colascione
2019-04-26 17:26       ` joel
2019-04-26 17:26         ` Joel Fernandes
2019-04-26 17:26         ` Joel Fernandes
2019-04-26 19:35         ` dancol
2019-04-26 19:35           ` Daniel Colascione
2019-04-26 19:35           ` Daniel Colascione
2019-04-26 20:31           ` joel
2019-04-26 20:31             ` Joel Fernandes
2019-04-26 20:31             ` Joel Fernandes
2019-04-26 13:42     ` joel
2019-04-26 13:42       ` Joel Fernandes
2019-04-26 13:42       ` Joel Fernandes
2019-04-25 22:24 ` [PATCH v1 1/2] Add polling support to pidfd Christian Brauner
2019-04-25 22:24   ` Christian Brauner
2019-04-25 22:24   ` Christian Brauner
2019-04-25 22:24   ` christian
2019-04-26 14:23   ` Joel Fernandes
2019-04-26 14:23     ` Joel Fernandes
2019-04-26 14:23     ` Joel Fernandes
2019-04-26 14:23     ` joel
2019-04-26 15:21     ` Christian Brauner
2019-04-26 15:21       ` Christian Brauner
2019-04-26 15:21       ` Christian Brauner
2019-04-26 15:21       ` christian
2019-04-26 15:31       ` Christian Brauner
2019-04-26 15:31         ` Christian Brauner
2019-04-26 15:31         ` Christian Brauner
2019-04-26 15:31         ` christian
2019-04-28 16:24   ` Oleg Nesterov
2019-04-28 16:24     ` Oleg Nesterov
2019-04-28 16:24     ` Oleg Nesterov
2019-04-28 16:24     ` oleg
2019-04-29 14:02     ` Joel Fernandes
2019-04-29 14:02       ` Joel Fernandes
2019-04-29 14:02       ` Joel Fernandes
2019-04-29 14:02       ` joel
2019-04-29 14:07       ` Joel Fernandes [this message]
2019-04-29 14:07         ` Joel Fernandes
2019-04-29 14:07         ` Joel Fernandes
2019-04-29 14:07         ` joel
2019-04-29 14:25         ` Oleg Nesterov
2019-04-29 14:25           ` Oleg Nesterov
2019-04-29 14:25           ` Oleg Nesterov
2019-04-29 14:25           ` oleg
2019-04-29 14:20       ` Oleg Nesterov
2019-04-29 14:20         ` Oleg Nesterov
2019-04-29 14:20         ` Oleg Nesterov
2019-04-29 14:20         ` oleg
2019-04-29 16:32         ` Joel Fernandes
2019-04-29 16:32           ` Joel Fernandes
2019-04-29 16:32           ` Joel Fernandes
2019-04-29 16:32           ` joel
2019-04-30 11:53           ` Oleg Nesterov
2019-04-30 11:53             ` Oleg Nesterov
2019-04-30 11:53             ` Oleg Nesterov
2019-04-30 11:53             ` oleg
2019-04-30 12:07             ` Oleg Nesterov
2019-04-30 12:07               ` Oleg Nesterov
2019-04-30 12:07               ` Oleg Nesterov
2019-04-30 12:07               ` oleg
2019-04-30 15:49             ` Joel Fernandes
2019-04-30 15:49               ` Joel Fernandes
2019-04-30 15:49               ` Joel Fernandes
2019-04-30 15:49               ` joel
2019-04-26 14:58 ` christian
2019-04-26 14:58   ` Christian Brauner
2019-04-26 14:58   ` Christian Brauner

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