Re: [PATCH V3 3/8] Add userspace buffers support in skb

2011-05-03 Thread Shirley Ma 
On Mon, 2011-05-02 at 13:53 +0300, Michael S. Tsirkin wrote:
 On Wed, Apr 20, 2011 at 12:47:57PM -0700, Shirley Ma wrote:
  This patch adds userspace buffers support in skb. A new struct
  skb_ubuf_info is needed to maintain the userspace buffers argument
  and index, a callback is used to notify userspace to release the
  buffers once lower device has done DMA (Last reference to that skb
  has gone).
  
  Signed-off-by: Shirley Ma x...@us.ibm.com
  ---
  
   include/linux/skbuff.h |   14 ++
   net/core/skbuff.c  |   15 ++-
   2 files changed, 28 insertions(+), 1 deletions(-)
  
  diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
  index d0ae90a..47a187b 100644
  --- a/include/linux/skbuff.h
  +++ b/include/linux/skbuff.h
  @@ -189,6 +189,16 @@ enum {
SKBTX_DRV_NEEDS_SK_REF = 1  3,
   };
   
  +/* The callback notifies userspace to release buffers when skb DMA
 is done in
  + * lower device, the desc is used to track userspace buffer index.
  + */
  +struct skb_ubuf_info {
  + /* support buffers allocation from userspace */
  + void(*callback)(struct sk_buff *);
  + void*arg;
  + size_t  desc;
  +};
  +
   /* This data is invariant across clones and lives at
* the end of the header data, ie. at skb-end.
*/
  @@ -211,6 +221,10 @@ struct skb_shared_info {
/* Intermediate layers must ensure that destructor_arg
 * remains valid until skb destructor */
void *  destructor_arg;
  +
  + /* DMA mapping from/to userspace buffers */
  + struct skb_ubuf_info ubuf;
  +
/* must be last field, see pskb_expand_head() */
skb_frag_t  frags[MAX_SKB_FRAGS];
   };
  diff --git a/net/core/skbuff.c b/net/core/skbuff.c
  index 7ebeed0..822c07d 100644
  --- a/net/core/skbuff.c
  +++ b/net/core/skbuff.c
  @@ -210,6 +210,8 @@ struct sk_buff *__alloc_skb(unsigned int size,
 gfp_t gfp_mask,
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(shinfo-dataref, 1);
  + shinfo-ubuf.callback = NULL;
  + shinfo-ubuf.arg = NULL;
kmemcheck_annotate_variable(shinfo-destructor_arg);
   
if (fclone) {
  @@ -327,7 +329,15 @@ static void skb_release_data(struct sk_buff
 *skb)
for (i = 0; i  skb_shinfo(skb)-nr_frags; i
 ++)
put_page(skb_shinfo(skb)-frags[i].page);
}
  -
  + /*
  +  * if skb buf is from userspace, we need to notify the
 caller
  +  * the lower device DMA has done;
  +  */
  + if (skb_shinfo(skb)-ubuf.callback) {
  + skb_shinfo(skb)-ubuf.callback(skb);
  + skb_shinfo(skb)-ubuf.callback = NULL;
  + skb_shinfo(skb)-ubuf.arg = NULL;
  + }
if (skb_has_frag_list(skb))
skb_drop_fraglist(skb);
   
 
 We probably don't need to touch arg if callback is NULL?

Yes.

  @@ -480,6 +490,9 @@ bool skb_recycle_check(struct sk_buff *skb, int
 skb_size)
if (irqs_disabled())
return false;
   
  + if (shinfo-ubuf.callback)
  + return false;
  +
if (skb_is_nonlinear(skb) || skb-fclone !=
 SKB_FCLONE_UNAVAILABLE)
return false;
 
 This is not the only API unsupported for these skbs, is it?
 Probably need to check and fail there as well. 

Yes, I am going through all these skbs to make sure covering all.

Thanks
Shirley

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Re: [PATCH V3 3/8] Add userspace buffers support in skb

2011-05-02 Thread Michael S. Tsirkin 
On Wed, Apr 20, 2011 at 12:47:57PM -0700, Shirley Ma wrote:
 This patch adds userspace buffers support in skb. A new struct
 skb_ubuf_info is needed to maintain the userspace buffers argument
 and index, a callback is used to notify userspace to release the
 buffers once lower device has done DMA (Last reference to that skb
 has gone).
 
 Signed-off-by: Shirley Ma x...@us.ibm.com
 ---
 
  include/linux/skbuff.h |   14 ++
  net/core/skbuff.c  |   15 ++-
  2 files changed, 28 insertions(+), 1 deletions(-)
 
 diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
 index d0ae90a..47a187b 100644
 --- a/include/linux/skbuff.h
 +++ b/include/linux/skbuff.h
 @@ -189,6 +189,16 @@ enum {
   SKBTX_DRV_NEEDS_SK_REF = 1  3,
  };
  
 +/* The callback notifies userspace to release buffers when skb DMA is done in
 + * lower device, the desc is used to track userspace buffer index.
 + */
 +struct skb_ubuf_info {
 + /* support buffers allocation from userspace */
 + void(*callback)(struct sk_buff *);
 + void*arg;
 + size_t  desc;
 +};
 +
  /* This data is invariant across clones and lives at
   * the end of the header data, ie. at skb-end.
   */
 @@ -211,6 +221,10 @@ struct skb_shared_info {
   /* Intermediate layers must ensure that destructor_arg
* remains valid until skb destructor */
   void *  destructor_arg;
 +
 + /* DMA mapping from/to userspace buffers */
 + struct skb_ubuf_info ubuf;
 +
   /* must be last field, see pskb_expand_head() */
   skb_frag_t  frags[MAX_SKB_FRAGS];
  };
 diff --git a/net/core/skbuff.c b/net/core/skbuff.c
 index 7ebeed0..822c07d 100644
 --- a/net/core/skbuff.c
 +++ b/net/core/skbuff.c
 @@ -210,6 +210,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t 
 gfp_mask,
   shinfo = skb_shinfo(skb);
   memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
   atomic_set(shinfo-dataref, 1);
 + shinfo-ubuf.callback = NULL;
 + shinfo-ubuf.arg = NULL;
   kmemcheck_annotate_variable(shinfo-destructor_arg);
  
   if (fclone) {
 @@ -327,7 +329,15 @@ static void skb_release_data(struct sk_buff *skb)
   for (i = 0; i  skb_shinfo(skb)-nr_frags; i++)
   put_page(skb_shinfo(skb)-frags[i].page);
   }
 -
 + /*
 +  * if skb buf is from userspace, we need to notify the caller
 +  * the lower device DMA has done;
 +  */
 + if (skb_shinfo(skb)-ubuf.callback) {
 + skb_shinfo(skb)-ubuf.callback(skb);
 + skb_shinfo(skb)-ubuf.callback = NULL;
 + skb_shinfo(skb)-ubuf.arg = NULL;
 + }
   if (skb_has_frag_list(skb))
   skb_drop_fraglist(skb);
  

We probably don't need to touch arg if callback is NULL?

 @@ -480,6 +490,9 @@ bool skb_recycle_check(struct sk_buff *skb, int skb_size)
   if (irqs_disabled())
   return false;
  
 + if (shinfo-ubuf.callback)
 + return false;
 +
   if (skb_is_nonlinear(skb) || skb-fclone != SKB_FCLONE_UNAVAILABLE)
   return false;

This is not the only API unsupported for these skbs, is it?
Probably need to check and fail there as well.

 
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[PATCH V3 3/8] Add userspace buffers support in skb

2011-04-20 Thread Shirley Ma 
This patch adds userspace buffers support in skb. A new struct
skb_ubuf_info is needed to maintain the userspace buffers argument
and index, a callback is used to notify userspace to release the
buffers once lower device has done DMA (Last reference to that skb
has gone).

Signed-off-by: Shirley Ma x...@us.ibm.com
---

 include/linux/skbuff.h |   14 ++
 net/core/skbuff.c  |   15 ++-
 2 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d0ae90a..47a187b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -189,6 +189,16 @@ enum {
SKBTX_DRV_NEEDS_SK_REF = 1  3,
 };
 
+/* The callback notifies userspace to release buffers when skb DMA is done in
+ * lower device, the desc is used to track userspace buffer index.
+ */
+struct skb_ubuf_info {
+   /* support buffers allocation from userspace */
+   void(*callback)(struct sk_buff *);
+   void*arg;
+   size_t  desc;
+};
+
 /* This data is invariant across clones and lives at
  * the end of the header data, ie. at skb-end.
  */
@@ -211,6 +221,10 @@ struct skb_shared_info {
/* Intermediate layers must ensure that destructor_arg
 * remains valid until skb destructor */
void *  destructor_arg;
+
+   /* DMA mapping from/to userspace buffers */
+   struct skb_ubuf_info ubuf;
+
/* must be last field, see pskb_expand_head() */
skb_frag_t  frags[MAX_SKB_FRAGS];
 };
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7ebeed0..822c07d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -210,6 +210,8 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t 
gfp_mask,
shinfo = skb_shinfo(skb);
memset(shinfo, 0, offsetof(struct skb_shared_info, dataref));
atomic_set(shinfo-dataref, 1);
+   shinfo-ubuf.callback = NULL;
+   shinfo-ubuf.arg = NULL;
kmemcheck_annotate_variable(shinfo-destructor_arg);
 
if (fclone) {
@@ -327,7 +329,15 @@ static void skb_release_data(struct sk_buff *skb)
for (i = 0; i  skb_shinfo(skb)-nr_frags; i++)
put_page(skb_shinfo(skb)-frags[i].page);
}
-
+   /*
+* if skb buf is from userspace, we need to notify the caller
+* the lower device DMA has done;
+*/
+   if (skb_shinfo(skb)-ubuf.callback) {
+   skb_shinfo(skb)-ubuf.callback(skb);
+   skb_shinfo(skb)-ubuf.callback = NULL;
+   skb_shinfo(skb)-ubuf.arg = NULL;
+   }
if (skb_has_frag_list(skb))
skb_drop_fraglist(skb);
 
@@ -480,6 +490,9 @@ bool skb_recycle_check(struct sk_buff *skb, int skb_size)
if (irqs_disabled())
return false;
 
+   if (shinfo-ubuf.callback)
+   return false;
+
if (skb_is_nonlinear(skb) || skb-fclone != SKB_FCLONE_UNAVAILABLE)
return false;
 


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