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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Olof Johansson <olof@lixom.net>
Cc: Dan Williams <dan.j.williams@gmail.com>,
	christopher.leech@intel.com, Jeff Garzik <jeff@garzik.org>,
	neilb@suse.de, linux-raid@vger.kernel.org, akpm@osdl.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dmaengine: clean up and abstract function types (was Re: [PATCH 08/19] dmaengine: enable multiple clients and operations)
Date: Tue, 19 Sep 2006 12:20:09 +0100	[thread overview]
Message-ID: <1158664809.32598.4.camel@localhost.localdomain> (raw)
In-Reply-To: <20060918200555.74aedeae@localhost.localdomain>

Ar Llu, 2006-09-18 am 20:05 -0500, ysgrifennodd Olof Johansson:
> On Mon, 18 Sep 2006 15:56:37 -0700 "Dan Williams" <dan.j.williams@gmail.com> wrote:

> op.src_type = PG; op.src = pg;
> op.dest_type = BUF; op.dest = buf;
> op.len = len;
> dma_async_commit(chan, op);

At OLS Linus suggested it should distinguish between sync and async
events for locking reasons.

	if(dma_async_commit(foo) == SYNC_COMPLETE) {
		finalise_stuff();
	}

	else		/* will call foo->callback(foo->dev_id) */

because otherwise you have locking complexities - the callback wants to
take locks to guard the object it works on but if it is called
synchronously - eg if hardware is busy and we fall back - it might
deadlock with the caller of dmaa_async_foo() who also needs to hold the
lock.

Alan


  reply	other threads:[~2006-09-19 10:57 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-11 23:00 [PATCH 00/19] Hardware Accelerated MD RAID5: Introduction Dan Williams
2006-09-11 23:17 ` [PATCH 01/19] raid5: raid5_do_soft_block_ops Dan Williams
2006-09-11 23:34   ` Jeff Garzik
2006-09-11 23:17 ` [PATCH 02/19] raid5: move write operations to a workqueue Dan Williams
2006-09-11 23:36   ` Jeff Garzik
2006-09-11 23:17 ` [PATCH 03/19] raid5: move check parity " Dan Williams
2006-09-11 23:17 ` [PATCH 04/19] raid5: move compute block " Dan Williams
2006-09-11 23:18 ` [PATCH 05/19] raid5: move read completion copies " Dan Williams
2006-09-11 23:18 ` [PATCH 06/19] raid5: move the reconstruct write expansion operation " Dan Williams
2006-09-11 23:18 ` [PATCH 07/19] raid5: remove compute_block and compute_parity5 Dan Williams
2006-09-11 23:18 ` [PATCH 08/19] dmaengine: enable multiple clients and operations Dan Williams
2006-09-11 23:44   ` Jeff Garzik
2006-09-12  0:14     ` Dan Williams
2006-09-12  0:52       ` Roland Dreier
2006-09-12  6:18         ` Dan Williams
2006-09-12  9:15           ` Evgeniy Polyakov
2006-09-13  4:04           ` Jeff Garzik
2006-09-15 16:38     ` Olof Johansson
2006-09-15 19:44       ` [PATCH] dmaengine: clean up and abstract function types (was Re: [PATCH 08/19] dmaengine: enable multiple clients and operations) Olof Johansson
2006-09-15 20:02         ` [PATCH] [v2] " Olof Johansson
2006-09-18 22:56         ` [PATCH] " Dan Williams
2006-09-19  1:05           ` Olof Johansson
2006-09-19 11:20             ` Alan Cox [this message]
2006-09-19 16:32               ` Olof Johansson
2006-09-11 23:18 ` [PATCH 09/19] dmaengine: reduce backend address permutations Dan Williams
2006-09-15 14:46   ` Olof Johansson
2006-09-11 23:18 ` [PATCH 10/19] dmaengine: expose per channel dma mapping characteristics to clients Dan Williams
2006-09-11 23:18 ` [PATCH 11/19] dmaengine: add memset as an asynchronous dma operation Dan Williams
2006-09-11 23:50   ` Jeff Garzik
2006-09-11 23:18 ` [PATCH 12/19] dmaengine: dma_async_memcpy_err for DMA engines that do not support memcpy Dan Williams
2006-09-11 23:51   ` Jeff Garzik
2006-09-11 23:18 ` [PATCH 13/19] dmaengine: add support for dma xor zero sum operations Dan Williams
2006-09-11 23:18 ` [PATCH 14/19] dmaengine: add dma_sync_wait Dan Williams
2006-09-11 23:52   ` Jeff Garzik
2006-09-11 23:18 ` [PATCH 15/19] dmaengine: raid5 dma client Dan Williams
2006-09-11 23:54   ` Jeff Garzik
2006-09-11 23:19 ` [PATCH 16/19] dmaengine: Driver for the Intel IOP 32x, 33x, and 13xx RAID engines Dan Williams
2006-09-15 14:57   ` Olof Johansson
2006-09-11 23:19 ` [PATCH 17/19] iop3xx: define IOP3XX_REG_ADDR[32|16|8] and clean up DMA/AAU defs Dan Williams
2006-09-11 23:55   ` Jeff Garzik
2006-09-11 23:19 ` [PATCH 18/19] iop3xx: Give Linux control over PCI (ATU) initialization Dan Williams
2006-09-11 23:56   ` Jeff Garzik
2006-09-11 23:19 ` [PATCH 19/19] iop3xx: IOP 32x and 33x support for the iop-adma driver Dan Williams
2006-09-11 23:38 ` [PATCH 00/19] Hardware Accelerated MD RAID5: Introduction Jeff Garzik
2006-09-11 23:53   ` Dan Williams
2006-09-12  2:41     ` Jeff Garzik
2006-09-12  5:47       ` Dan Williams
2006-09-13  4:05         ` Jeff Garzik
2006-09-13  7:15 ` Jakob Oestergaard
2006-09-13 19:17   ` Dan Williams
2006-09-14  7:42     ` Jakob Oestergaard
2006-10-11  1:46       ` Dan Williams
2006-10-08 22:18 ` Neil Brown
2006-10-10 18:23   ` Dan Williams
2006-10-11  2:44     ` Neil Brown

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