From: David Miller <davem@davemloft.net>
To: alan@lxorguk.ukuu.org.uk
Cc: jarkao2@gmail.com, shemminger@linux-foundation.org,
mbreuer@majjas.com, akpm@linux-foundation.org, flyboy@gmail.com,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
mchan@broadcom.com, 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 14:53:16 -0800 (PST) [thread overview]
Message-ID: <20100120.145316.109996493.davem@davemloft.net> (raw)
In-Reply-To: <20100120222414.57909d14@lxorguk.ukuu.org.uk>
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: Wed, 20 Jan 2010 22:24:14 +0000
>> > Seems like an underlying bug in the DMA api. Maybe it just can't
>> > handle operations on partial mapping.
>> >
>> > Other drivers with same problem:
>> > bnx2, cassini, pcnet32, r8169, rrunner, skge, sungem, tg3,
>>
>> It seems using the same length (even without pci_unmap_len()) is
>> crucial here, but I hope maintainers (added to CC) will take care.
>
> The API needs fixing - if you've got a large mapping and you want to sync
> part of it then we need to support that. Now it might well be that the
> implementation on some braindead platform has to sync the entire thing,
> and some implementations entire pages or cache lines.
>
> You can't fix this in the drivers, they requested a service and they
> don't have enough information nor is it their job to know about all the
> platform specific rules.
Absolutely and %100 agreed, the DMA debugging layer and documentation
are both buggy.
The intention from the beginning was always to allow partial SYNCs
exactly for the reasons Alan and myself are mentioning here.
next prev parent reply other threads:[~2010-01-20 22:53 UTC|newest]
Thread overview: 95+ 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
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 [this message]
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
2010-02-03 17:16 ` 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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