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Date: Thu, 28 Jan 2010 09:08:35 -0800 From: Stephen Hemminger <shemminger@...ux-foundation.org> To: Michael Breuer <mbreuer@...jas.com> Cc: Jarek Poplawski <jarkao2@...il.com>, David Miller <davem@...emloft.net>, akpm@...ux-foundation.org, flyboy@...il.com, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, Michael Chan <mchan@...adcom.com>, Don Fry <pcnet32@...izon.net>, Francois Romieu <romieu@...zoreil.com>, Matt Carlson <mcarlson@...adcom.com> Subject: Re: Hang: 2.6.32.4 sky2/DMAR (was [PATCH] sky2: Fix WARNING: at lib/dma-debug.c:902 check_sync) On Thu, 28 Jan 2010 11:43:16 -0500 Michael Breuer <mbreuer@...jas.com> wrote: > Update: I played with dma-debug. Was being disabled due to lack of > memory. I forced it back on while pumping traffic through and got this: > Jan 28 11:39:30 mail kernel: ------------[ cut here ]------------ > Jan 28 11:39:30 mail kernel: WARNING: at lib/dma-debug.c:902 > check_sync+0xc1/0x43f() > Jan 28 11:39:30 mail kernel: Hardware name: System Product Name > Jan 28 11:39:30 mail kernel: sky2 0000:06:00.0: DMA-API: device driver > tries to sync DMA memory it has not allocated [device This test in dma-debug is bogus. Because the debug code matches dma based on address and size; and is perfectly valid to sync a value less than size. This is the patch I sent earlier, it isn't 100% correct but it will let you keep testing .................................... This should fix the dma-debug API code (and documentation), to avoid false positives when sync is done on a partial map. Signed-off-by: Stephen Hemminger <shemminger@...tta.com> --- a/Documentation/DMA-API.txt 2010-01-20 15:17:01.390143729 -0800 +++ b/Documentation/DMA-API.txt 2010-01-20 15:18:48.967875255 -0800 @@ -377,9 +377,10 @@ void pci_dma_sync_sg(struct pci_dev *hwdev, struct scatterlist *sg, int nelems, int direction) -Synchronise a single contiguous or scatter/gather mapping. All the -parameters must be the same as those passed into the single mapping -API. +Synchronise a single contiguous or scatter/gather mapping. The +device and handle must be the same as those passed into the single mapping +API. The size can be less than the original mapping if only part +of the mapping needs to be accessed. Notes: You must do this: --- a/lib/dma-debug.c 2010-01-20 15:22:55.919519883 -0800 +++ b/lib/dma-debug.c 2010-01-20 15:26:31.648895638 -0800 @@ -285,11 +285,9 @@ static struct dma_debug_entry *hash_buck } /* - * If we have multiple matches but no perfect-fit, just return - * NULL. + * If we have multiple matches but no perfect-fit + * return best value and let caller deal with it. */ - ret = (matches == 1) ? ret : NULL; - return ret; } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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