If we're sure not to go native XDP, there's no need for several things like bh and rcu stuffs. So this patch introduces a helper to build skb and hold page refcnt. When we found we will go through skb path, build skb directly.
Signed-off-by: Jason Wang <[email protected]> --- drivers/net/tun.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 257cf7342d54..946c6148ed75 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1635,6 +1635,23 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, return true; } +static struct sk_buff *__tun_build_skb(struct page_frag *alloc_frag, char *buf, + int buflen, int len, int pad, int delta) +{ + struct sk_buff *skb = build_skb(buf, buflen); + + if (!skb) + return ERR_PTR(-ENOMEM); + + skb_reserve(skb, pad - delta); + skb_put(skb, len); + + get_page(alloc_frag->page); + alloc_frag->offset += buflen; + + return skb; +} + static struct sk_buff *tun_build_skb(struct tun_struct *tun, struct tun_file *tfile, struct iov_iter *from, @@ -1642,7 +1659,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, int len, int *skb_xdp) { struct page_frag *alloc_frag = ¤t->task_frag; - struct sk_buff *skb; struct bpf_prog *xdp_prog; int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); unsigned int delta = 0; @@ -1672,10 +1688,12 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, * of xdp_prog above, this should be rare and for simplicity * we do XDP on skb in case the headroom is not enough. */ - if (hdr->gso_type || !xdp_prog) + if (hdr->gso_type || !xdp_prog) { *skb_xdp = 1; - else - *skb_xdp = 0; + return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta); + } + + *skb_xdp = 0; local_bh_disable(); rcu_read_lock(); @@ -1719,22 +1737,13 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, trace_xdp_exception(tun->dev, xdp_prog, act); /* fall through */ case XDP_DROP: - goto err_xdp; + goto out; } } rcu_read_unlock(); local_bh_enable(); - skb = build_skb(buf, buflen); - if (!skb) - return ERR_PTR(-ENOMEM); - - skb_reserve(skb, pad - delta); - skb_put(skb, len); - get_page(alloc_frag->page); - alloc_frag->offset += buflen; - - return skb; + return __tun_build_skb(alloc_frag, buf, buflen, len, pad, delta); err_redirect: put_page(alloc_frag->page); -- 2.17.1 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
