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From: Jiri Kosina <jikos@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Miroslav Benes <mbenes@suse.cz>,
	jeyu@redhat.com, pmladek@suse.com, jslaby@suse.cz,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
	huawei.libin@huawei.com, minfei.huang@yahoo.com
Subject: Re: [RFC PATCH] livepatch: allow removal of a disabled patch
Date: Wed, 4 May 2016 00:31:12 +0200 (CEST)	[thread overview]
Message-ID: <alpine.LNX.2.00.1605040024010.27942@cbobk.fhfr.pm> (raw)
In-Reply-To: <20160503213709.g66xr624pwn7oguu@treble>

On Tue, 3 May 2016, Josh Poimboeuf wrote:

> > 1. Do we really need a completion? If I am not missing something
> > kobject_del() always waits for sysfs callers to leave thanks to kernfs
> > active protection.
> 
> What do you mean by "kernfs active protection"?  I see that
> kernfs_remove() gets the kernfs_mutex lock, but I can't find anywhere
> that a write to a sysfs file uses that lock.
> 
> I'm probably missing something...

I don't want to speak on Miroslav's behalf, but I'm pretty sure that what 
he has on mind is per-kernfs_node active refcounting kernfs does (see 
kernfs_node->active, and especially it's usage in __kernfs_remove()).

More specifically, execution of store() and show() sysfs callbacks is 
guaranteed (by kernfs) to happen with that particular attribute's active 
reference held for reading (and that makes it impossible for that 
attribute to vanish prematurely).

-- 
Jiri Kosina
SUSE Labs

  reply	other threads:[~2016-05-03 22:31 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-02 11:57 [RFC PATCH] livepatch: allow removal of a disabled patch Miroslav Benes
2016-05-02 15:08 ` Josh Poimboeuf
2016-05-03  8:16   ` Miroslav Benes
2016-05-31 23:13     ` Jiri Kosina
2016-05-03 21:37 ` Josh Poimboeuf
2016-05-03 22:31   ` Jiri Kosina [this message]
2016-05-04  2:39     ` Josh Poimboeuf
2016-05-04  3:36       ` Josh Poimboeuf
2016-05-04 11:58         ` Miroslav Benes
2016-05-04 13:14           ` Josh Poimboeuf
2016-05-04 14:35             ` Miroslav Benes
2016-05-04 16:14               ` Josh Poimboeuf
2016-05-05  8:28                 ` Miroslav Benes
2016-05-05 13:27                   ` Josh Poimboeuf
2016-05-05 14:25                     ` Miroslav Benes
2016-05-05 15:04                       ` Josh Poimboeuf
2016-05-05 21:08                         ` Jiri Kosina
2016-05-06  0:42                         ` Jessica Yu
2016-05-06  7:51                           ` Miroslav Benes

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