xdp: rely on skb pointer reference in do_xdp_generic and netif_receive_generic_xdp

Rely on skb pointer reference instead of the skb pointer in do_xdp_generic
and netif_receive_generic_xdp routine signatures.
This is a preliminary patch to add multi-buff support for xdp running in
generic mode where we will need to reallocate the skb to avoid
linearization and we will need to make it visible to do_xdp_generic()
caller.

Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Reviewed-by: Toke Hoiland-Jorgensen <toke@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/c09415b1f48c8620ef4d76deed35050a7bddf7c2.1707729884.git.lorenzo@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index b472f2c972d84936d8a53f7784bddec7a1370a0c..bc80fc1d576e5ae27d7c99c7ae7778fa5f2e72f2 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1926,7 +1926,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
                rcu_read_lock();
                xdp_prog = rcu_dereference(tun->xdp_prog);
                if (xdp_prog) {
-                       ret = do_xdp_generic(xdp_prog, skb);
+                       ret = do_xdp_generic(xdp_prog, &skb);
                        if (ret != XDP_PASS) {
                                rcu_read_unlock();
                                local_bh_enable();
@@ -2516,7 +2516,7 @@ build:
        skb_record_rx_queue(skb, tfile->queue_index);
 
        if (skb_xdp) {
-               ret = do_xdp_generic(xdp_prog, skb);
+               ret = do_xdp_generic(xdp_prog, &skb);
                if (ret != XDP_PASS) {
                        ret = 0;
                        goto out;

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 07cefa32eafa93dd1a4602de892d0ee1cbf2e22b..a3f9c95da51eec9a02d01ba2e1d7dc380eb08ffe 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3958,7 +3958,7 @@ static inline void dev_consume_skb_any(struct sk_buff *skb)
 u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
                             struct bpf_prog *xdp_prog);
 void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog);
-int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb);
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff **pskb);
 int netif_rx(struct sk_buff *skb);
 int __netif_rx(struct sk_buff *skb);
 

diff --git a/net/core/dev.c b/net/core/dev.c
index e19bdf1421e0a93021a720327baf0eb9ccf503d6..ffeb0e0279fedfb2d21ad67325375f7296eecd08 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4936,10 +4936,11 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
        return act;
 }
 
-static u32 netif_receive_generic_xdp(struct sk_buff *skb,
+static u32 netif_receive_generic_xdp(struct sk_buff **pskb,
                                     struct xdp_buff *xdp,
                                     struct bpf_prog *xdp_prog)
 {
+       struct sk_buff *skb = *pskb;
        u32 act = XDP_DROP;
 
        /* Reinjected packets coming from act_mirred or similar should
@@ -5020,24 +5021,24 @@ void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog)
 
 static DEFINE_STATIC_KEY_FALSE(generic_xdp_needed_key);
 
-int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
+int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff **pskb)
 {
        if (xdp_prog) {
                struct xdp_buff xdp;
                u32 act;
                int err;
 
-               act = netif_receive_generic_xdp(skb, &xdp, xdp_prog);
+               act = netif_receive_generic_xdp(pskb, &xdp, xdp_prog);
                if (act != XDP_PASS) {
                        switch (act) {
                        case XDP_REDIRECT:
-                               err = xdp_do_generic_redirect(skb->dev, skb,
+                               err = xdp_do_generic_redirect((*pskb)->dev, *pskb,
                                                              &xdp, xdp_prog);
                                if (err)
                                        goto out_redir;
                                break;
                        case XDP_TX:
-                               generic_xdp_tx(skb, xdp_prog);
+                               generic_xdp_tx(*pskb, xdp_prog);
                                break;
                        }
                        return XDP_DROP;
@@ -5045,7 +5046,7 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb)
        }
        return XDP_PASS;
 out_redir:
-       kfree_skb_reason(skb, SKB_DROP_REASON_XDP);
+       kfree_skb_reason(*pskb, SKB_DROP_REASON_XDP);
        return XDP_DROP;
 }
 EXPORT_SYMBOL_GPL(do_xdp_generic);
@@ -5368,7 +5369,8 @@ another_round:
                int ret2;
 
                migrate_disable();
-               ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog), skb);
+               ret2 = do_xdp_generic(rcu_dereference(skb->dev->xdp_prog),
+                                     &skb);
                migrate_enable();
 
                if (ret2 != XDP_PASS) {