skbuff: allow 'slow_gro' for skb carring sock reference

This change leverages the infrastructure introduced by the previous
patches to allow soft devices passing to the GRO engine owned skbs
without impacting the fast-path.

It's up to the GRO caller ensuring the slow_gro bit validity before
invoking the GRO engine. The new helper skb_prepare_for_gro() is
introduced for that goal.

On slow_gro, skbs are aggregated only with equal sk.
Additionally, skb truesize on GRO recycle and free is correctly
updated so that sk wmem is not changed by the GRO processing.

rfc-> v1:
 - fixed bad truesize on dev_gro_receive NAPI_FREE
 - use the existing state bit

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sock.h b/include/net/sock.h
index f23cb25..ff1be7e 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2249,6 +2249,15 @@ static inline __must_check bool skb_set_owner_sk_safe(struct sk_buff *skb, struc
        return false;
 }
 
+static inline void skb_prepare_for_gro(struct sk_buff *skb)
+{
+       if (skb->destructor != sock_wfree) {
+               skb_orphan(skb);
+               return;
+       }
+       skb->slow_gro = 1;
+}
+
 void sk_reset_timer(struct sock *sk, struct timer_list *timer,
                    unsigned long expires);
 

diff --git a/net/core/dev.c b/net/core/dev.c
index 19565f7..dcc87fc 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6034,6 +6034,7 @@ static void gro_list_prepare(const struct list_head *head,
                        struct tc_skb_ext *p_ext;
 #endif
 
+                       diffs |= p->sk != skb->sk;
                        diffs |= skb_metadata_dst_cmp(p, skb);
                        diffs |= skb_get_nfct(p) ^ skb_get_nfct(skb);
 
@@ -6311,6 +6312,7 @@ static void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
        skb_shinfo(skb)->gso_type = 0;
        skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
        if (unlikely(skb->slow_gro)) {
+               skb_orphan(skb);
                skb_ext_reset(skb);
                nf_reset_ct(skb);
                skb->slow_gro = 0;

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d04e286..fcbd977 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -958,6 +958,7 @@ void napi_skb_free_stolen_head(struct sk_buff *skb)
                nf_reset_ct(skb);
                skb_dst_drop(skb);
                skb_ext_put(skb);
+               skb_orphan(skb);
                skb->slow_gro = 0;
        }
        napi_skb_cache_put(skb);
@@ -3892,6 +3893,9 @@ int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
        NAPI_GRO_CB(p)->last = skb;
        NAPI_GRO_CB(p)->count++;
        p->data_len += skb->len;
+
+       /* sk owenrship - if any - completely transferred to the aggregated packet */
+       skb->destructor = NULL;
        p->truesize += skb->truesize;
        p->len += skb->len;
 
@@ -4259,6 +4263,7 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
        unsigned int headlen = skb_headlen(skb);
        unsigned int len = skb_gro_len(skb);
        unsigned int delta_truesize;
+       unsigned int new_truesize;
        struct sk_buff *lp;
 
        if (unlikely(p->len + len >= 65536 || NAPI_GRO_CB(skb)->flush))
@@ -4290,10 +4295,10 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
                skb_frag_size_sub(frag, offset);
 
                /* all fragments truesize : remove (head size + sk_buff) */
-               delta_truesize = skb->truesize -
-                                SKB_TRUESIZE(skb_end_offset(skb));
+               new_truesize = SKB_TRUESIZE(skb_end_offset(skb));
+               delta_truesize = skb->truesize - new_truesize;
 
-               skb->truesize -= skb->data_len;
+               skb->truesize = new_truesize;
                skb->len -= skb->data_len;
                skb->data_len = 0;
 
@@ -4322,12 +4327,16 @@ int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb)
                memcpy(frag + 1, skbinfo->frags, sizeof(*frag) * skbinfo->nr_frags);
                /* We dont need to clear skbinfo->nr_frags here */
 
-               delta_truesize = skb->truesize - SKB_DATA_ALIGN(sizeof(struct sk_buff));
+               new_truesize = SKB_TRUESIZE(sizeof(struct sk_buff));
+               delta_truesize = skb->truesize - new_truesize;
+               skb->truesize = new_truesize;
                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
                goto done;
        }
 
 merge:
+       /* sk owenrship - if any - completely transferred to the aggregated packet */
+       skb->destructor = NULL;
        delta_truesize = skb->truesize;
        if (offset > headlen) {
                unsigned int eat = offset - headlen;