* [PATCH net] net/mlx4_en: Fix pages never dma unmapped on rx
@ 2013-10-06 12:57 Amir Vadai
2013-10-06 14:22 ` Eric Dumazet
0 siblings, 1 reply; 3+ messages in thread
From: Amir Vadai @ 2013-10-06 12:57 UTC (permalink / raw)
To: netdev; +Cc: Amir Vadai, Or Gerlitz, Eugenia Emantayev, Eric Dumazet
This patch fixes a bug introduced by commit 51151a16 (mlx4: allow
order-0 memory allocations in RX path).
dma_unmap_page never reached because condition to detect last fragment
in page is wrong. offset+frag_stride can't be greater than size, need to
make sure no additional frag will fit in page => compare offset +
frag_stride + next_frag_size instead.
next_frag_size could be next frag in the same skb, or the first frag in
the next.
CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
---
drivers/net/ethernet/mellanox/mlx4/en_rx.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index dec455c..44d8865 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -131,8 +131,11 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
int i)
{
const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
+ u16 next_frag_end = frags[i].offset + frag_info->frag_stride;
- if (frags[i].offset + frag_info->frag_stride > frags[i].size)
+ next_frag_end += frags[(i + 1) % priv->num_frags].size;
+
+ if (next_frag_end > frags[i].size)
dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
PCI_DMA_FROMDEVICE);
--
1.8.3.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH net] net/mlx4_en: Fix pages never dma unmapped on rx
2013-10-06 12:57 [PATCH net] net/mlx4_en: Fix pages never dma unmapped on rx Amir Vadai
@ 2013-10-06 14:22 ` Eric Dumazet
2013-10-06 15:05 ` Amir Vadai
0 siblings, 1 reply; 3+ messages in thread
From: Eric Dumazet @ 2013-10-06 14:22 UTC (permalink / raw)
To: Amir Vadai; +Cc: netdev, Or Gerlitz, Eugenia Emantayev, Eric Dumazet
On Sun, 2013-10-06 at 14:57 +0200, Amir Vadai wrote:
> This patch fixes a bug introduced by commit 51151a16 (mlx4: allow
> order-0 memory allocations in RX path).
>
> dma_unmap_page never reached because condition to detect last fragment
> in page is wrong. offset+frag_stride can't be greater than size, need to
> make sure no additional frag will fit in page => compare offset +
> frag_stride + next_frag_size instead.
> next_frag_size could be next frag in the same skb, or the first frag in
> the next.
>
> CC: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Amir Vadai <amirv@mellanox.com>
> ---
> drivers/net/ethernet/mellanox/mlx4/en_rx.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> index dec455c..44d8865 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> @@ -131,8 +131,11 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
> int i)
> {
> const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
> + u16 next_frag_end = frags[i].offset + frag_info->frag_stride;
>
Hmm, could you make this an u32 ?
frags[i].offset and frags[i].size are u32
Maybe some folks want to use PAGE_SIZE=65536 or whatever high order
allocs
> - if (frags[i].offset + frag_info->frag_stride > frags[i].size)
> + next_frag_end += frags[(i + 1) % priv->num_frags].size;
> +
> + if (next_frag_end > frags[i].size)
> dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
> PCI_DMA_FROMDEVICE);
>
Not sure I understand how this can work. How was this tested ?
frags[i + 1].size is the size of the page containing next fragment,
so now test should _always_ trigger.
(We could rename @size to @page_size to avoid confusion)
I think you meant to add the size of the next fragment ?
What about following instead (I also removed the divide operation)
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index dec455c..22444de 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -131,10 +131,17 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
int i)
{
const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
+ u32 next_frag_end = frags[i].offset + frag_info->frag_stride;
- if (frags[i].offset + frag_info->frag_stride > frags[i].size)
+ frag_info++;
+ if (i + 1 == priv->num_frags)
+ frag_info = &priv->frag_info[0];
+
+ next_frag_end += frag_info->frag_stride;
+
+ if (next_frag_end > frags[i].size)
dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
- PCI_DMA_FROMDEVICE);
+ PCI_DMA_FROMDEVICE);
if (frags[i].page)
put_page(frags[i].page);
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH net] net/mlx4_en: Fix pages never dma unmapped on rx
2013-10-06 14:22 ` Eric Dumazet
@ 2013-10-06 15:05 ` Amir Vadai
0 siblings, 0 replies; 3+ messages in thread
From: Amir Vadai @ 2013-10-06 15:05 UTC (permalink / raw)
To: Eric Dumazet; +Cc: netdev, Or Gerlitz, Eugenia Emantayev, Eric Dumazet
On 06/10/2013 17:22, Eric Dumazet wrote:
> On Sun, 2013-10-06 at 14:57 +0200, Amir Vadai wrote:
>> This patch fixes a bug introduced by commit 51151a16 (mlx4: allow
>> order-0 memory allocations in RX path).
>>
>> dma_unmap_page never reached because condition to detect last fragment
>> in page is wrong. offset+frag_stride can't be greater than size, need to
>> make sure no additional frag will fit in page => compare offset +
>> frag_stride + next_frag_size instead.
>> next_frag_size could be next frag in the same skb, or the first frag in
>> the next.
>>
>> CC: Eric Dumazet <edumazet@google.com>
>> Signed-off-by: Amir Vadai <amirv@mellanox.com>
>> ---
>> drivers/net/ethernet/mellanox/mlx4/en_rx.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> index dec455c..44d8865 100644
>> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
>> @@ -131,8 +131,11 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
>> int i)
>> {
>> const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
>> + u16 next_frag_end = frags[i].offset + frag_info->frag_stride;
>>
>
> Hmm, could you make this an u32 ?
>
> frags[i].offset and frags[i].size are u32
>
> Maybe some folks want to use PAGE_SIZE=65536 or whatever high order
> allocs
>
>
>> - if (frags[i].offset + frag_info->frag_stride > frags[i].size)
>> + next_frag_end += frags[(i + 1) % priv->num_frags].size;
>> +
>> + if (next_frag_end > frags[i].size)
>> dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
>> PCI_DMA_FROMDEVICE);
>>
>
> Not sure I understand how this can work. How was this tested ?
>
> frags[i + 1].size is the size of the page containing next fragment,
> so now test should _always_ trigger.
>
> (We could rename @size to @page_size to avoid confusion)
>
> I think you meant to add the size of the next fragment ?
>
> What about following instead (I also removed the divide operation)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> index dec455c..22444de 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> @@ -131,10 +131,17 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
> int i)
> {
> const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
> + u32 next_frag_end = frags[i].offset + frag_info->frag_stride;
>
> - if (frags[i].offset + frag_info->frag_stride > frags[i].size)
> + frag_info++;
> + if (i + 1 == priv->num_frags)
> + frag_info = &priv->frag_info[0];
> +
> + next_frag_end += frag_info->frag_stride;
> +
> + if (next_frag_end > frags[i].size)
> dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
> - PCI_DMA_FROMDEVICE);
> + PCI_DMA_FROMDEVICE);
>
> if (frags[i].page)
> put_page(frags[i].page);
>
>
It looks good.
Will also change it into a small patchset with a new patch to rename
@size to @page_size and @offset to @page_offset.
I Will send it after I finish testing.
(Previously I had the typo added just after I removed the prints I used
while testing).
Thanks,
Amir
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-10-06 15:06 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-10-06 12:57 [PATCH net] net/mlx4_en: Fix pages never dma unmapped on rx Amir Vadai
2013-10-06 14:22 ` Eric Dumazet
2013-10-06 15:05 ` Amir Vadai
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox