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From: Greg KH <greg@kroah.com>
To: Jerome Marchand <jmarchan@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>, Jens Axboe <jaxboe@fusionio.com>,
	Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] kref: add kref_test_and_get
Date: Tue, 4 Jan 2011 12:57:20 -0800	[thread overview]
Message-ID: <20110104205720.GA4180@kroah.com> (raw)
In-Reply-To: <4D23423A.60707@redhat.com>

On Tue, Jan 04, 2011 at 04:52:26PM +0100, Jerome Marchand wrote:
> 
> Add kref_test_and_get() function, which atomically add a reference only if
> refcount is not zero. This prevent to add a reference to an object that is
> already being removed.

We just removed a function like this recently as it really isn't the
solution for what you need here at all.

Please use a lock that protects the desctruction of the kref, like the
rest of the kernel, to keep someone from grabing a reference while the
device could be going away.  That's the only way to safely do this.

See the archives for why this overall, isn't a good idea for a kref to
have this type of function.

thanks,

greg k-h

  parent reply	other threads:[~2011-01-04 21:00 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-06  9:44 [PATCH 1/2] Don't merge different partition's IOs Yasuaki Ishimatsu
2010-12-06 16:08 ` Linus Torvalds
2010-12-07  7:18   ` Satoru Takeuchi
2010-12-07 18:39     ` Vivek Goyal
2010-12-08  7:33     ` Jens Axboe
2010-12-08  7:59       ` Satoru Takeuchi
2010-12-08  8:06         ` Jens Axboe
2010-12-08  8:11           ` Satoru Takeuchi
2010-12-08 14:46             ` Jens Axboe
2010-12-08 15:51               ` Vivek Goyal
2010-12-08 15:58                 ` Vivek Goyal
2010-12-10 11:22                   ` Jerome Marchand
2010-12-10 16:12               ` Jerome Marchand
2010-12-10 16:55                 ` Vivek Goyal
2010-12-14 20:25                   ` Jens Axboe
2010-12-17 13:42                     ` [PATCH] block: fix accounting bug on cross partition merges Jerome Marchand
2010-12-17 19:06                       ` Jens Axboe
2010-12-17 22:32                         ` Vivek Goyal
2010-12-23 15:10                         ` Jerome Marchand
2010-12-23 15:39                           ` Vivek Goyal
2010-12-23 17:04                             ` Jerome Marchand
2010-12-24 19:29                               ` Vivek Goyal
2011-01-04 15:52                                 ` [PATCH 1/2] kref: add kref_test_and_get Jerome Marchand
2011-01-04 15:55                                   ` [PATCH 2/2] block: fix accounting bug on cross partition merges Jerome Marchand
2011-01-04 21:00                                     ` Greg KH
2011-01-05 13:51                                       ` Jerome Marchand
2011-01-05 16:00                                         ` Greg KH
2011-01-05 16:19                                           ` Jerome Marchand
2011-01-05 16:27                                             ` Greg KH
2011-01-05 13:55                                       ` Jens Axboe
2011-01-05 15:58                                         ` Greg KH
2011-01-05 18:46                                           ` Jens Axboe
2011-01-05 20:08                                             ` Greg KH
2011-01-05 21:38                                               ` Jens Axboe
2011-01-05 22:16                                                 ` Greg KH
2011-01-06  9:46                                                   ` Jens Axboe
2011-01-05 14:00                                     ` Jens Axboe
2011-01-05 14:09                                       ` Jerome Marchand
2011-01-05 14:17                                         ` Jens Axboe
2011-01-04 16:05                                   ` [PATCH 1/2] kref: add kref_test_and_get Eric Dumazet
2011-01-05 15:02                                     ` [PATCH 1/2 v2] " Jerome Marchand
2011-01-05 15:43                                       ` Alexey Dobriyan
2011-01-05 15:57                                         ` Greg KH
2011-01-05 15:56                                       ` Greg KH
2011-01-04 20:57                                   ` Greg KH [this message]
2011-01-05 13:35                                     ` [PATCH 1/2] " Jerome Marchand
2011-01-05 15:55                                       ` Greg KH

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