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From: Lin Ming <lxy@ss.pku.edu.cn>
To: Lukas Czerner <lczerner@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
	Jens Axboe <jaxboe@fusionio.com>,
	Mike Snitzer <snitzer@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: blkdev_issue_discard() hangs forever if the underlying storage device is removed
Date: Mon, 29 Aug 2011 23:26:49 +0800	[thread overview]
Message-ID: <CAF1ivSbwSXhz7sKzKrA=3CcTi6hJHP4T5PYsgefpEQx7DBnD5A@mail.gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1108291712590.3904@dhcp-27-109.brq.redhat.com>

On Mon, Aug 29, 2011 at 11:16 PM, Lukas Czerner <lczerner@redhat.com> wrote:
> On Mon, 29 Aug 2011, Lin Ming wrote:
>
>> On Mon, Aug 29, 2011 at 10:42 PM, Lukas Czerner <lczerner@redhat.com> wrote:
>> > On Mon, 29 Aug 2011, Lin Ming wrote:
>> >
>> >> On Mon, Aug 29, 2011 at 7:56 PM, Lukas Czerner <lczerner@redhat.com> wrote:
>> >> >
>> >> > Regarding the atomic operations I do not think that implicit memory
>> >> > barriers are needed here as atomic_dec_and_test() implies memory
>> >>
>> >> Which implicit memory barrier you are talking about?
>> >
>> > smp_mb() at both side of the operation as documented here in
>> > Documentation/memory-barriers.txt
>>
>> Thanks for the info.
>>
>> But I don't follow you ... why that implicit memory barriers are NOT needed?
>>
>
> Oh, I am sorry I have actually wanted to say that *explicit* memory
> barriers are no needed in that case. Sorry for the confusion!

Make sense now :)

Thanks.

  reply	other threads:[~2011-08-29 15:26 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-27  6:11 blkdev_issue_discard() hangs forever if the underlying storage device is removed Bart Van Assche
2011-08-29 11:56 ` Lukas Czerner
2011-08-29 14:15   ` Lin Ming
2011-08-29 14:42     ` Lukas Czerner
2011-08-29 15:11       ` Lin Ming
2011-08-29 15:16         ` Lukas Czerner
2011-08-29 15:26           ` Lin Ming [this message]
2011-08-29 17:56   ` Bart Van Assche
2011-08-30  2:01     ` Dave Chinner
2011-08-30 10:38       ` Bart Van Assche
2011-09-27 17:57       ` Bart Van Assche
2011-08-30 10:34     ` Lukas Czerner
2011-09-22 17:26 ` Bart Van Assche

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