From: Oleg Nesterov <oleg@redhat.com>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Davide Libenzi <davidel@xmailserver.org>,
Eric Dumazet <eric.dumazet@gmail.com>, Greg KH <greg@kroah.com>,
Jason Baron <jbaron@redhat.com>,
Roland McGrath <roland@hack.frob.com>,
Eugene Teo <eugeneteo@kernel.sg>,
Maxime Bizon <mbizon@freebox.fr>,
Denys Vlasenko <dvlasenk@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()
Date: Thu, 1 Mar 2012 20:26:36 +0100 [thread overview]
Message-ID: <20120301192636.GA10709@redhat.com> (raw)
In-Reply-To: <CAObL_7GdhNPNsSiTF+GfbJ3_8ud8px6=LBH173uy14y58FMivg@mail.gmail.com>
On 02/29, Andrew Lutomirski wrote:
>
> On Wed, Feb 29, 2012 at 12:06 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> > On 02/29, Andy Lutomirski wrote:
> >>
> >> On 02/24/2012 11:07 AM, Oleg Nesterov wrote:
> >> > This patch adds the special event, POLLFREE, currently only for
> >> > epoll. It expects that init_poll_funcptr()'ed hook should do the
> >> > necessary cleanup. Perhaps it should be defined as EPOLLFREE in
> >> > eventpoll.
> >>
> >> I have a bunch of userspace code that uses signalfd via epoll. Does
> >> this affect the ABI?
> >
> > I hope not ;)
> >
>
> Excellent!
>
> To avoid further confusion, would it make sense to update the comment
> in poll.h to indicate that POLLFREE is only for epoll and is internal
> to the kernel?
Agreed. Or perhaps we can simply use POLLREMOVE instead...
But note that nobody (including me) likes this fix, just I was asked
to make something simple/backportable. Probably it will be reverted
later.
If not, then perhaps it makes sense to do a couple of simple changes
on top to cleanup the usage of POLLFREE and to ensure that POLLHUP
is actually delivered (the latter will be user-visible).
Oleg.
next prev parent reply other threads:[~2012-03-01 19:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120222173326.GA7139@redhat.com>
2012-02-22 17:33 ` [PATCH 1/4] signalfd: introduce signalfd_cleanup() Oleg Nesterov
2012-02-22 17:34 ` [PATCH 2/4] epoll: introduce POLLFREE for ep_poll_callback() Oleg Nesterov
2012-02-22 17:34 ` [PATCH 3/4] signalfd: signalfd_cleanup() can race with remove_wait_queue() Oleg Nesterov
2012-02-22 17:35 ` [PATCH 4/4] epoll: ep_unregister_pollwait() can use the freed pwq->whead Oleg Nesterov
2012-02-23 15:44 ` Oleg Nesterov
2012-02-23 22:17 ` Linus Torvalds
2012-02-24 19:06 ` [PATCH v2 0/2] signalfd/epoll fixes Oleg Nesterov
2012-02-24 19:07 ` [PATCH v2 1/2] epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree() Oleg Nesterov
2012-02-29 19:57 ` Andy Lutomirski
2012-02-29 20:06 ` Oleg Nesterov
2012-02-29 20:16 ` Andrew Lutomirski
2012-03-01 19:26 ` Oleg Nesterov [this message]
2012-02-24 19:07 ` [PATCH v2 2/2] epoll: ep_unregister_pollwait() can use the freed pwq->whead Oleg Nesterov
2012-02-24 20:23 ` [PATCH v2 0/2] signalfd/epoll fixes Linus Torvalds
2012-02-24 23:14 ` Linus Torvalds
2012-02-25 16:08 ` Oleg Nesterov
2012-02-25 19:00 ` Linus Torvalds
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