From: David Miller <davem@davemloft.net>
To: jarkao2@gmail.com
Cc: shemminger@linux-foundation.org, mchan@broadcom.com,
mbreuer@majjas.com, akpm@linux-foundation.org, flyboy@gmail.com,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
pcnet32@verizon.net, romieu@fr.zoreil.com, mcarlson@broadcom.com
Subject: Re: [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync
Date: Wed, 20 Jan 2010 14:50:10 -0800 (PST) [thread overview]
Message-ID: <20100120.145010.80864889.davem@davemloft.net> (raw)
In-Reply-To: <20100120205842.GA3072@del.dom.local>
From: Jarek Poplawski <jarkao2@gmail.com>
Date: Wed, 20 Jan 2010 21:58:42 +0100
> Yes, and it's mainly for lib/dma-debug (until it's not verified dmar
> errors reported by Michael Breuer could be connected). So, I'm not
> sure for now how serious this warning could be. On the other hand,
> Documentation/(PCI-?)DMA-mapping, mentioned by Stephen, doesn't seem
> to allow or use in examples the "size" different than mapped.
Someone find me even one actual implemenetation of the DMA APIs, not
the debugging code, which can't handle a partial sync correctly, then
we can talk.
As the person who originally created the PCI DMA APIs I can tell
you the intention was definitely to allow arbitrary SYNC lengths
and there was no requirement that the length needed to be the
same as that used in the mapping call.
Nothing else makes sense. People sync when they have a partially used
buffer and want to copy the data out then recycle the big original
buffer back to the chip. I knew this when creating the PCI DMA APIs
because I first tried to use them in network drivers and that's what
so many of them do.
Currently all we have is an overly anal DMA debugging layer check, and
some speculation that it might or might not fix some real bug.
next prev parent reply other threads:[~2010-01-20 22:50 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-20 9:41 [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync Jarek Poplawski
2010-01-20 18:03 ` Stephen Hemminger
2010-01-20 20:11 ` Michael Chan
2010-01-20 20:30 ` Stephen Hemminger
2010-01-20 20:58 ` Jarek Poplawski
2010-01-20 22:50 ` David Miller [this message]
2010-01-20 22:45 ` David Miller
2010-01-20 18:09 ` Stephen Hemminger
2010-01-20 22:24 ` Alan Cox
2010-01-20 22:53 ` David Miller
2010-01-20 22:53 ` Jarek Poplawski
2010-01-21 15:22 ` FUJITA Tomonori
2010-01-21 18:41 ` Jarek Poplawski
2010-01-22 5:11 ` FUJITA Tomonori
2010-01-22 6:38 ` David Miller
2010-02-03 1:18 ` FUJITA Tomonori
2010-02-03 1:27 ` David Miller
2010-01-21 19:59 ` Michael Breuer
2010-01-21 20:41 ` Jarek Poplawski
2010-01-21 20:46 ` Michael Breuer
2010-01-21 21:02 ` Jarek Poplawski
2010-01-22 18:01 ` Hang: 2.6.32.4 sky2/DMAR (was [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync) Michael Breuer
2010-01-22 21:53 ` Jarek Poplawski
2010-01-22 22:14 ` Michael Breuer
2010-01-22 23:06 ` Jarek Poplawski
2010-01-22 23:25 ` Michael Breuer
2010-01-22 23:46 ` Jarek Poplawski
2010-01-22 23:50 ` Michael Breuer
2010-01-23 23:21 ` Jarek Poplawski
2010-01-24 1:53 ` Michael Breuer
2010-01-27 15:34 ` Michael Breuer
2010-01-27 16:50 ` Stephen Hemminger
2010-01-27 16:57 ` Michael Breuer
2010-01-27 17:45 ` Stephen Hemminger
2010-01-27 17:57 ` Michael Breuer
2010-01-27 18:33 ` Michael Breuer
2010-01-27 23:54 ` Hang: 2.6.32.4 sky2/DMAR David Miller
2010-01-27 17:56 ` Hang: 2.6.32.4 sky2/DMAR (was [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync) Stephen Hemminger
2010-01-27 17:58 ` Michael Breuer
2010-01-27 18:08 ` Michael Breuer
2010-01-27 18:45 ` Michael Breuer
2010-01-27 19:23 ` Jarek Poplawski
2010-01-27 19:32 ` Jarek Poplawski
2010-01-28 15:32 ` Michael Breuer
2010-01-28 16:43 ` Michael Breuer
2010-01-28 17:08 ` Stephen Hemminger
2010-01-28 18:46 ` Michael Breuer
2010-01-28 22:34 ` Jarek Poplawski
2010-01-28 22:43 ` Michael Breuer
2010-01-28 22:56 ` Jarek Poplawski
2010-01-28 22:59 ` Michael Breuer
2010-01-28 23:36 ` [PATCH] sky2: receive dma mapping error handling Stephen Hemminger
2010-01-29 0:05 ` Michael Breuer
2010-01-30 16:30 ` Michael Breuer
2010-01-30 16:31 ` Michael Breuer
2010-01-31 0:34 ` Jarek Poplawski
2010-01-31 4:17 ` Michael Breuer
2010-01-31 22:25 ` Jarek Poplawski
2010-01-31 23:58 ` Michael Breuer
2010-01-31 4:55 ` Michael Breuer
2010-01-31 18:50 ` Michael Breuer
2010-01-31 21:58 ` Michael Breuer
2010-01-31 22:18 ` Jarek Poplawski
2010-02-01 0:19 ` Michael Breuer
2010-02-01 4:26 ` Michael Breuer
2010-02-01 10:47 ` Jarek Poplawski
2010-02-01 9:17 ` [PATCH v2] sky2: Fix transmit dma mapping handling Jarek Poplawski
2010-02-01 17:52 ` Michael Breuer
2010-02-01 18:08 ` [PATCH] sky2: receive dma mapping error handling Stephen Hemminger
2010-02-01 18:20 ` Stephen Hemminger
2010-02-01 18:44 ` Michael Breuer
2010-02-01 20:13 ` Jarek Poplawski
2010-02-01 20:41 ` Jarek Poplawski
2010-02-01 21:27 ` [PATCH v3] " Jarek Poplawski
2010-02-01 22:29 ` Stephen Hemminger
2010-02-01 22:46 ` Jarek Poplawski
2010-02-01 22:51 ` Stephen Hemminger
2010-02-01 21:42 ` [PATCH v3b resent] sky2: Fix transmit dma mapping handling Jarek Poplawski
2010-02-03 4:07 ` [PATCH] sky2: receive dma mapping error handling Michael Breuer
2010-02-03 16:47 ` Michael Breuer
2010-02-03 16:56 ` Stephen Hemminger
2010-02-03 17:07 ` Michael Breuer
2010-02-03 18:23 ` Justin P. Mattock
2010-02-03 18:25 ` Stephen Hemminger
2010-02-03 18:48 ` Justin P. Mattock
2010-11-06 16:57 ` Sky2 2.6.36-09934-g2aab243 DMAR error with tcp timestamp enabled Michael Breuer
2010-11-08 3:13 ` Stephen Hemminger
2010-11-08 3:38 ` Michael Breuer
2010-11-08 16:46 ` Stephen Hemminger
2010-02-03 17:16 ` [PATCH] sky2: receive dma mapping error handling Justin P. Mattock
2010-02-02 22:44 ` Andi Kleen
2012-01-16 16:39 ` Regression: sky2 kernel between 3.1 and 3.2.1 (last known good 3.0.9) Michael Breuer
2012-01-20 14:24 ` Michael Breuer
2012-01-20 16:10 ` Stephen Hemminger
2012-01-20 16:17 ` Michael Breuer
2012-01-20 16:26 ` Stephen Hemminger
2012-01-20 16:44 ` Michael Breuer
2012-01-21 15:29 ` Michael Breuer
2012-01-22 18:03 ` Stephen Hemminger
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