tun: make tun_build_skb() thread safe (0bbd7dad) · Commits · 戴 / test

tun_build_skb() is not thread safe since it uses per queue page frag, this will break things when multiple threads are sending through same queue. Switch to use per-thread generator (no lock involved). Fixes: ("tap: use build_skb() for small packet") Tested-by:

Jason Wang <jasowang@redhat.com> Signed-off-by:

Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:

Jason Wang <jasowang@redhat.com> Acked-by:

Michael S. Tsirkin <mst@redhat.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

drivers/net/tun.c

+1 −6

Original line number	Diff line number	Diff line
		@@ -175,7 +175,6 @@ struct tun_file {
		struct list_head next;
		struct tun_struct *detached;
		struct skb_array tx_array;
		struct page_frag alloc_frag;
		};

		struct tun_flow_entry {
		@@ -578,8 +577,6 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
		}
		if (tun)
		skb_array_cleanup(&tfile->tx_array);
		if (tfile->alloc_frag.page)
		put_page(tfile->alloc_frag.page);
		sock_put(&tfile->sk);
		}
		}
		@@ -1272,7 +1269,7 @@ static struct sk_buff tun_build_skb(struct tun_struct tun,
		struct virtio_net_hdr *hdr,
		int len, int *generic_xdp)
		{
		struct page_frag *alloc_frag = &tfile->alloc_frag;
		struct page_frag *alloc_frag = &current->task_frag;
		struct sk_buff *skb;
		struct bpf_prog *xdp_prog;
		int buflen = SKB_DATA_ALIGN(len + TUN_RX_PAD) +
		@@ -2580,8 +2577,6 @@ static int tun_chr_open(struct inode inode, struct file file)
		tfile->sk.sk_write_space = tun_sock_write_space;
		tfile->sk.sk_sndbuf = INT_MAX;

		tfile->alloc_frag.page = NULL;

		file->private_data = tfile;
		INIT_LIST_HEAD(&tfile->next);

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