linux-kernel - Re: [PATCH] dma-debug: disable DMA_API

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Date:	Thu, 11 Jun 2009 10:10:32 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Torsten Kaiser <just.for.lkml@...glemail.com>
CC:	FUJITA Tomonori <fujita.tomonori@....ntt.co.jp>,
	Linus Torvalds <torvalds@...ux-foundation.org>, mingo@...e.hu,
	lethal@...ux-sh.org, hancockrwd@...il.com, jens.axboe@...cle.com,
	bharrosh@...asas.com, linux-kernel@...r.kernel.org,
	linux-scsi@...r.kernel.org
Subject: Re: [PATCH] dma-debug: disable DMA_API_DEBUG for now

On Wed, Jun 10, 2009 at 10:41:53PM +0200, Torsten Kaiser wrote:
> I applied this patch to the just released 2.6.30, but it does not fix
> the false warning on my System.
> 
> Jun 10 21:10:14 treogen [ 2611.715341] ------------[ cut here ]------------
> Jun 10 21:10:14 treogen [ 2611.715359] WARNING: at lib/dma-debug.c:565
> check_unmap+0x536/0x620()
> Jun 10 21:10:14 treogen [ 2611.715363] Hardware name: KFN5-D SLI
> Jun 10 21:10:14 treogen [ 2611.715369] sata_sil24 0000:04:00.0:
> DMA-API: device driver frees DMA sg list with different entry count [map count=2] [unmap count=1]

Ok, thats because we need also to check for sg_call_ents in the best-fit
checks. Can you please test if you can reproduce it with the attached
patch?

>From 1e83c7eab546314ad9dbe08602d243bb83e93b50 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <joerg.roedel@....com>
Date: Thu, 11 Jun 2009 10:03:42 +0200
Subject: [PATCH] dma-debug: check for sg_call_ents in best-fit algorithm too

If we don't check for sg_call_ents the hash_bucket_find function might
still return the wrong dma_debug_entry for sg mappings.

Signed-off-by: Joerg Roedel <joerg.roedel@....com>
---
 lib/dma-debug.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index ad65fc0..eb86ec3 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -262,11 +262,12 @@ static struct dma_debug_entry *hash_bucket_find(struct hash_bucket *bucket,
 		 */
 		matches += 1;
 		match_lvl = 0;
-		entry->size      == ref->size      ? ++match_lvl : match_lvl;
-		entry->type      == ref->type      ? ++match_lvl : match_lvl;
-		entry->direction == ref->direction ? ++match_lvl : match_lvl;
+		entry->size         == ref->size         ? ++match_lvl : 0;
+		entry->type         == ref->type         ? ++match_lvl : 0;
+		entry->direction    == ref->direction    ? ++match_lvl : 0;
+		entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0;
 
-		if (match_lvl == 3) {
+		if (match_lvl == 4) {
 			/* perfect-fit - return the result */
 			return entry;
 		} else if (match_lvl > last_lvl) {
-- 
1.6.3.1


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