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 <[email protected]> > --- > > 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. > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
