2012-10-18 15:38:47

by Ming Lei

[permalink] [raw]
Subject: [PATCH] lib/dma-debug.c: fix __hash_bucket_find

If there is only one match, the unique matched entry should be returned.

Without the fix, the commit f62566214fe31c9f9b3218a42f1b19e6a9e6844a

dma-debug: new interfaces to debug dma mapping errors

can't work reliably because only device and dma_addr are passed to
dma_mapping_error().

Cc: Joerg Roedel <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
---
lib/dma-debug.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 94aa94e..be132f3 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -283,6 +283,10 @@ static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket,
if (!match(ref, entry))
continue;

+ /* record the first match */
+ if (!ret)
+ ret = entry;
+
/*
* Some drivers map the same physical address multiple
* times. Without a hardware IOMMU this results in the
--
1.7.9.5


2012-10-18 15:53:44

by Ming Lei

[permalink] [raw]
Subject: Re: [PATCH] lib/dma-debug.c: fix __hash_bucket_find

Hi,

Below v1 should be more efficient and simper, sorry for the noise.


Thanks,
--
Ming Lei

--
>From d275d195794ff80e018145f2fae714b35ddc49e2 Mon Sep 17 00:00:00 2001
From: Ming Lei <[email protected]>
Date: Thu, 18 Oct 2012 23:30:57 +0800
Subject: [PATCH v1] lib/dma-debug.c: fix __hash_bucket_find

If there is only one match, the unique matched entry should be returned.

Without the fix, the commit f62566214fe31c9f9b3218a42f1b19e6a9e6844a

dma-debug: new interfaces to debug dma mapping errors

can't work reliably because only device and dma_addr are passed to
dma_mapping_error().

Cc: Joerg Roedel <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
---
lib/dma-debug.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 94aa94e..59f4a1a 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -277,7 +277,7 @@ static struct dma_debug_entry
*__hash_bucket_find(struct hash_bucket *bucket,
match_fn match)
{
struct dma_debug_entry *entry, *ret = NULL;
- int matches = 0, match_lvl, last_lvl = 0;
+ int matches = 0, match_lvl, last_lvl = -1;

list_for_each_entry(entry, &bucket->list, list) {
if (!match(ref, entry))
@@ -306,7 +306,7 @@ static struct dma_debug_entry
*__hash_bucket_find(struct hash_bucket *bucket,
} else if (match_lvl > last_lvl) {
/*
* We found an entry that fits better then the
- * previous one
+ * previous one or it is the 1st match.
*/
last_lvl = match_lvl;
ret = entry;
--
1.7.9.5

2012-10-18 17:21:01

by Shuah Khan

[permalink] [raw]
Subject: Re: [PATCH] lib/dma-debug.c: fix __hash_bucket_find

On Thu, 2012-10-18 at 23:53 +0800, Ming Lei wrote:
> Hi,
>
> Below v1 should be more efficient and simper, sorry for the noise.
>
>
> Thanks,
> --
> Ming Lei
>
> --
> From d275d195794ff80e018145f2fae714b35ddc49e2 Mon Sep 17 00:00:00 2001
> From: Ming Lei <[email protected]>
> Date: Thu, 18 Oct 2012 23:30:57 +0800
> Subject: [PATCH v1] lib/dma-debug.c: fix __hash_bucket_find
>
> If there is only one match, the unique matched entry should be returned.
>
> Without the fix, the commit f62566214fe31c9f9b3218a42f1b19e6a9e6844a
>
> dma-debug: new interfaces to debug dma mapping errors
>
> can't work reliably because only device and dma_addr are passed to
> dma_mapping_error().
>
> Cc: Joerg Roedel <[email protected]>
> Cc: Shuah Khan <[email protected]>
> Cc: Paul Gortmaker <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Signed-off-by: Ming Lei <[email protected]>
> ---
> lib/dma-debug.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 94aa94e..59f4a1a 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -277,7 +277,7 @@ static struct dma_debug_entry
> *__hash_bucket_find(struct hash_bucket *bucket,
> match_fn match)
> {
> struct dma_debug_entry *entry, *ret = NULL;
> - int matches = 0, match_lvl, last_lvl = 0;
> + int matches = 0, match_lvl, last_lvl = -1;
>
> list_for_each_entry(entry, &bucket->list, list) {
> if (!match(ref, entry))
> @@ -306,7 +306,7 @@ static struct dma_debug_entry
> *__hash_bucket_find(struct hash_bucket *bucket,
> } else if (match_lvl > last_lvl) {
> /*
> * We found an entry that fits better then the
> - * previous one
> + * previous one or it is the 1st match.
> */
> last_lvl = match_lvl;
> ret = entry;

Thanks for finding and fixing the problem. This fixes the problem
Fengguang Wu reported: adding him to the thread.

https://lkml.org/lkml/2012/10/14/233

I have a reliable test case and test system that reproduces the problem.
Re-tested it with and without patch and didn't see the warning with your
patch.

That said, this patch is malformed and didn't apply cleanly.
You have my

Tested-by: Shuah Khan <[email protected]>

Thanks,
-- Shuah

2012-10-19 01:13:40

by Ming Lei

[permalink] [raw]
Subject: Re: [PATCH] lib/dma-debug.c: fix __hash_bucket_find

On Fri, Oct 19, 2012 at 1:20 AM, Shuah Khan <[email protected]> wrote:

> Thanks for finding and fixing the problem. This fixes the problem
> Fengguang Wu reported: adding him to the thread.
>
> https://lkml.org/lkml/2012/10/14/233
>
> I have a reliable test case and test system that reproduces the problem.
> Re-tested it with and without patch and didn't see the warning with your
> patch.
>
> That said, this patch is malformed and didn't apply cleanly.
> You have my
>
> Tested-by: Shuah Khan <[email protected]>

OK, I will submit it again for merge.

Thanks,
--
Ming Lei