AcoSail/kernel_optimize_test
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tun: reserve extra headroom only when XDP is set

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We reserve headroom unconditionally which could cause unnecessary
stress on socket memory accounting because of increased trusesize. Fix
this by only reserve extra headroom when XDP is set.

Cc: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jason Wang 2017-09-04 11:36:08 +08:00 committed by David S. Miller
parent 9e776f225d
commit 7df13219d7
1 changed files with 18 additions and 8 deletions
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26
drivers/net/tun.c
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@ -108,7 +108,7 @@ do { \
#endif
#define TUN_HEADROOM 256
#define TUN_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD + TUN_HEADROOM)
#define TUN_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
/* TUN device flags */
@ -1272,25 +1272,35 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
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) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
unsigned int delta = 0;
char *buf;
size_t copied;
bool xdp_xmit = false;
int err;
int err, pad = TUN_RX_PAD;
rcu_read_lock();
xdp_prog = rcu_dereference(tun->xdp_prog);
if (xdp_prog)
pad += TUN_HEADROOM;
buflen += SKB_DATA_ALIGN(len + pad);
rcu_read_unlock();
if (unlikely(!skb_page_frag_refill(buflen, alloc_frag, GFP_KERNEL)))
return ERR_PTR(-ENOMEM);
buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
copied = copy_page_from_iter(alloc_frag->page,
alloc_frag->offset + TUN_RX_PAD,
alloc_frag->offset + pad,
len, from);
if (copied != len)
return ERR_PTR(-EFAULT);
if (hdr->gso_type)
/* There's a small window that XDP may be set after the check
* 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)
*generic_xdp = 1;
else
*generic_xdp = 0;
@ -1303,7 +1313,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
u32 act;
xdp.data_hard_start = buf;
xdp.data = buf + TUN_RX_PAD;
xdp.data = buf + pad;
xdp.data_end = xdp.data + len;
orig_data = xdp.data;
act = bpf_prog_run_xdp(xdp_prog, &xdp);
@ -1339,7 +1349,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
return ERR_PTR(-ENOMEM);
}
skb_reserve(skb, TUN_RX_PAD - delta);
skb_reserve(skb, pad - delta);
skb_put(skb, len + delta);
get_page(alloc_frag->page);
alloc_frag->offset += buflen;