Fwd: dma_skb_copy_datagram_iovec not EXPORTed

Fwd: dma_skb_copy_datagram_iovec not EXPORTed

[Sam Hopkins]

Hello,

I'm forwarding along a message sent to kernelnewbies as I was directed
to address my question to this list.  I am not a member of netdev, so
please copy me on all discussion of this topic.

Cheers,

Sam

---

Greetings,

I am a developer of the kernel AoE (ATA over Ethernet) driver.  I am
attempting to add dma offloading of data receive, following in TCP's
footsteps via config option NET_DMA.  There is a function in
net/core/user_dma.c, dma_skb_copy_datagram_iovec, that appears to be
exactly what I need, but this function is not EXPORTed for use by
external modules.

Since the NET_DMA option is documented as "Network: TCP receive copy
offload" perhaps it's just an oversight that anyone else might benefit
from it?

Cheers,

Sam

Re: Fwd: dma_skb_copy_datagram_iovec not EXPORTed

[Randy Dunlap]

On Tue, 5 Jun 2007 10:56:58 -0400 Sam Hopkins wrote:

> Hello,
> 
> I'm forwarding along a message sent to kernelnewbies as I was directed
> to address my question to this list.  I am not a member of netdev, so
> please copy me on all discussion of this topic.
> 
> Cheers,
> 
> Sam
> 
> ---
> 
> Greetings,
> 
> I am a developer of the kernel AoE (ATA over Ethernet) driver.  I am
> attempting to add dma offloading of data receive, following in TCP's
> footsteps via config option NET_DMA.  There is a function in
> net/core/user_dma.c, dma_skb_copy_datagram_iovec, that appears to be
> exactly what I need, but this function is not EXPORTed for use by
> external modules.
> 
> Since the NET_DMA option is documented as "Network: TCP receive copy
> offload" perhaps it's just an oversight that anyone else might benefit
> from it?

Makes sense to me.  Maybe someone in the hierarchy will agree,
or you may need to just send a patch and see if it is accepted.


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

[PATCH 1/1] make network DMA usable for non-tcp drivers

[Ed L. Cashin]

Here is a patch against the netdev-2.6 git tree that makes the net DMA
feature usable for drivers like the ATA over Ethernet block driver,
which can use dma_skb_copy_datagram_iovec when receiving data from the
network.

The change was suggested on kernelnewbies.

  http://article.gmane.org/gmane.linux.kernel.kernelnewbies/21663

Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
---
 drivers/dma/Kconfig |    2 +-
 net/core/user_dma.c |    2 ++
 2 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 72be6c6..270d23e 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -14,7 +14,7 @@ config DMA_ENGINE
 comment "DMA Clients"
 
 config NET_DMA
-	bool "Network: TCP receive copy offload"
+	bool "Network: receive copy offload"
 	depends on DMA_ENGINE && NET
 	default y
 	---help---
diff --git a/net/core/user_dma.c b/net/core/user_dma.c
index 0ad1cd5..69d0b15 100644
--- a/net/core/user_dma.c
+++ b/net/core/user_dma.c
@@ -130,3 +130,5 @@ end:
 fault:
 	return -EFAULT;
 }
+
+EXPORT_SYMBOL(dma_skb_copy_datagram_iovec);
-- 
1.5.2.1

Re: [PATCH 1/1] make network DMA usable for non-tcp drivers

[Andrew Morton]

On Fri, 8 Jun 2007 10:30:53 -0400
"Ed L. Cashin" <ecashin@coraid.com> wrote:

> Here is a patch against the netdev-2.6 git tree that makes the net DMA
> feature usable for drivers like the ATA over Ethernet block driver,
> which can use dma_skb_copy_datagram_iovec when receiving data from the
> network.
> 
> The change was suggested on kernelnewbies.
> 
>   http://article.gmane.org/gmane.linux.kernel.kernelnewbies/21663
> 
> Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
> ---
>  drivers/dma/Kconfig |    2 +-
>  net/core/user_dma.c |    2 ++
>  2 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 72be6c6..270d23e 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -14,7 +14,7 @@ config DMA_ENGINE
>  comment "DMA Clients"
>  
>  config NET_DMA
> -	bool "Network: TCP receive copy offload"
> +	bool "Network: receive copy offload"
>  	depends on DMA_ENGINE && NET
>  	default y
>  	---help---
> diff --git a/net/core/user_dma.c b/net/core/user_dma.c
> index 0ad1cd5..69d0b15 100644
> --- a/net/core/user_dma.c
> +++ b/net/core/user_dma.c
> @@ -130,3 +130,5 @@ end:
>  fault:
>  	return -EFAULT;
>  }
> +
> +EXPORT_SYMBOL(dma_skb_copy_datagram_iovec);

We wouldn't want to merge this until code which actually uses the export is
also merged.

Re: [PATCH 1/1] make network DMA usable for non-tcp drivers

[Dan Williams]

> > @@ -130,3 +130,5 @@ end:
> >  fault:
> >       return -EFAULT;
> >  }
> > +
> > +EXPORT_SYMBOL(dma_skb_copy_datagram_iovec);
>
> We wouldn't want to merge this until code which actually uses the export is
> also merged.
>

...and I recommend EXPORT_SYMBOL_GPL following the lead of the other
async dma options in -mm.