[PATCH AUTOSEL 5.10 27/85] net: hns3: add handling for xmit skb with recursive fraglist

From: Sasha Levin
Date: Wed May 05 2021 - 13:01:40 EST

From: Yunsheng Lin <linyunsheng@xxxxxxxxxx>

[ Upstream commit d5d5e0193ee8f88efbbc7f1471087255657bc19a ]

Currently hns3 driver only handle the xmit skb with one level of
fraglist skb, add handling for multi level by calling hns3_tx_bd_num()
recursively when calculating bd num and calling hns3_fill_skb_to_desc()
recursively when filling tx desc.

When the skb has a fraglist level of 24, the skb is simply dropped and
stats.max_recursion_level is added to record the error. Move the stat
handling from hns3_nic_net_xmit() to hns3_nic_maybe_stop_tx() in order
to handle different error stat and add the 'max_recursion_level' and
'hw_limitation' stat.

Note that the max recursive level as 24 is chose according to below:
commit 48a1df65334b ("skbuff: return -EMSGSIZE in skb_to_sgvec to
prevent overflow").

And that we are not able to find a testcase to verify the recursive
fraglist case, so Fixes tag is not provided.

Reported-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
Signed-off-by: Huazhong Tan <tanhuazhong@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
.../net/ethernet/hisilicon/hns3/hns3_enet.c | 115 +++++++++++-------
.../net/ethernet/hisilicon/hns3/hns3_enet.h | 2 +
.../ethernet/hisilicon/hns3/hns3_ethtool.c | 2 +
3 files changed, 78 insertions(+), 41 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index a362516a3185..8ef7896dbc95 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -1192,23 +1192,21 @@ static unsigned int hns3_skb_bd_num(struct sk_buff *skb, unsigned int *bd_size,
}

static unsigned int hns3_tx_bd_num(struct sk_buff *skb, unsigned int *bd_size,
- u8 max_non_tso_bd_num)
+ u8 max_non_tso_bd_num, unsigned int bd_num,
+ unsigned int recursion_level)
{
+#define HNS3_MAX_RECURSION_LEVEL 24
+
struct sk_buff *frag_skb;
- unsigned int bd_num = 0;

/* If the total len is within the max bd limit */
- if (likely(skb->len <= HNS3_MAX_BD_SIZE && !skb_has_frag_list(skb) &&
+ if (likely(skb->len <= HNS3_MAX_BD_SIZE && !recursion_level &&
+ !skb_has_frag_list(skb) &&
skb_shinfo(skb)->nr_frags < max_non_tso_bd_num))
return skb_shinfo(skb)->nr_frags + 1U;

- /* The below case will always be linearized, return
- * HNS3_MAX_BD_NUM_TSO + 1U to make sure it is linearized.
- */
- if (unlikely(skb->len > HNS3_MAX_TSO_SIZE ||
- (!skb_is_gso(skb) && skb->len >
- HNS3_MAX_NON_TSO_SIZE(max_non_tso_bd_num))))
- return HNS3_MAX_TSO_BD_NUM + 1U;
+ if (unlikely(recursion_level >= HNS3_MAX_RECURSION_LEVEL))
+ return UINT_MAX;

bd_num = hns3_skb_bd_num(skb, bd_size, bd_num);

@@ -1216,7 +1214,8 @@ static unsigned int hns3_tx_bd_num(struct sk_buff *skb, unsigned int *bd_size,
return bd_num;

skb_walk_frags(skb, frag_skb) {
- bd_num = hns3_skb_bd_num(frag_skb, bd_size, bd_num);
+ bd_num = hns3_tx_bd_num(frag_skb, bd_size, max_non_tso_bd_num,
+ bd_num, recursion_level + 1);
if (bd_num > HNS3_MAX_TSO_BD_NUM)
return bd_num;
}
@@ -1276,6 +1275,43 @@ void hns3_shinfo_pack(struct skb_shared_info *shinfo, __u32 *size)
size[i] = skb_frag_size(&shinfo->frags[i]);
}

+static int hns3_skb_linearize(struct hns3_enet_ring *ring,
+ struct sk_buff *skb,
+ u8 max_non_tso_bd_num,
+ unsigned int bd_num)
+{
+ /* 'bd_num == UINT_MAX' means the skb' fraglist has a
+ * recursion level of over HNS3_MAX_RECURSION_LEVEL.
+ */
+ if (bd_num == UINT_MAX) {
+ u64_stats_update_begin(&ring->syncp);
+ ring->stats.over_max_recursion++;
+ u64_stats_update_end(&ring->syncp);
+ return -ENOMEM;
+ }
+
+ /* The skb->len has exceeded the hw limitation, linearization
+ * will not help.
+ */
+ if (skb->len > HNS3_MAX_TSO_SIZE ||
+ (!skb_is_gso(skb) && skb->len >
+ HNS3_MAX_NON_TSO_SIZE(max_non_tso_bd_num))) {
+ u64_stats_update_begin(&ring->syncp);
+ ring->stats.hw_limitation++;
+ u64_stats_update_end(&ring->syncp);
+ return -ENOMEM;
+ }
+
+ if (__skb_linearize(skb)) {
+ u64_stats_update_begin(&ring->syncp);
+ ring->stats.sw_err_cnt++;
+ u64_stats_update_end(&ring->syncp);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
static int hns3_nic_maybe_stop_tx(struct hns3_enet_ring *ring,
struct net_device *netdev,
struct sk_buff *skb)
@@ -1285,7 +1321,7 @@ static int hns3_nic_maybe_stop_tx(struct hns3_enet_ring *ring,
unsigned int bd_size[HNS3_MAX_TSO_BD_NUM + 1U];
unsigned int bd_num;

- bd_num = hns3_tx_bd_num(skb, bd_size, max_non_tso_bd_num);
+ bd_num = hns3_tx_bd_num(skb, bd_size, max_non_tso_bd_num, 0, 0);
if (unlikely(bd_num > max_non_tso_bd_num)) {
if (bd_num <= HNS3_MAX_TSO_BD_NUM && skb_is_gso(skb) &&
!hns3_skb_need_linearized(skb, bd_size, bd_num,
@@ -1294,16 +1330,11 @@ static int hns3_nic_maybe_stop_tx(struct hns3_enet_ring *ring,
goto out;
}

- if (__skb_linearize(skb))
+ if (hns3_skb_linearize(ring, skb, max_non_tso_bd_num,
+ bd_num))
return -ENOMEM;

bd_num = hns3_tx_bd_count(skb->len);
- if ((skb_is_gso(skb) && bd_num > HNS3_MAX_TSO_BD_NUM) ||
- (!skb_is_gso(skb) &&
- bd_num > max_non_tso_bd_num)) {
- trace_hns3_over_max_bd(skb);
- return -ENOMEM;
- }

u64_stats_update_begin(&ring->syncp);
ring->stats.tx_copy++;
@@ -1327,6 +1358,10 @@ static int hns3_nic_maybe_stop_tx(struct hns3_enet_ring *ring,
return bd_num;
}

+ u64_stats_update_begin(&ring->syncp);
+ ring->stats.tx_busy++;
+ u64_stats_update_end(&ring->syncp);
+
return -EBUSY;
}

@@ -1374,6 +1409,7 @@ static int hns3_fill_skb_to_desc(struct hns3_enet_ring *ring,
struct sk_buff *skb, enum hns_desc_type type)
{
unsigned int size = skb_headlen(skb);
+ struct sk_buff *frag_skb;
int i, ret, bd_num = 0;

if (size) {
@@ -1398,6 +1434,15 @@ static int hns3_fill_skb_to_desc(struct hns3_enet_ring *ring,
bd_num += ret;
}

+ skb_walk_frags(skb, frag_skb) {
+ ret = hns3_fill_skb_to_desc(ring, frag_skb,
+ DESC_TYPE_FRAGLIST_SKB);
+ if (unlikely(ret < 0))
+ return ret;
+
+ bd_num += ret;
+ }
+
return bd_num;
}

@@ -1428,8 +1473,6 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
struct hns3_enet_ring *ring = &priv->ring[skb->queue_mapping];
struct netdev_queue *dev_queue;
int pre_ntu, next_to_use_head;
- struct sk_buff *frag_skb;
- int bd_num = 0;
bool doorbell;
int ret;

@@ -1445,15 +1488,8 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
ret = hns3_nic_maybe_stop_tx(ring, netdev, skb);
if (unlikely(ret <= 0)) {
if (ret == -EBUSY) {
- u64_stats_update_begin(&ring->syncp);
- ring->stats.tx_busy++;
- u64_stats_update_end(&ring->syncp);
hns3_tx_doorbell(ring, 0, true);
return NETDEV_TX_BUSY;
- } else if (ret == -ENOMEM) {
- u64_stats_update_begin(&ring->syncp);
- ring->stats.sw_err_cnt++;
- u64_stats_update_end(&ring->syncp);
}

hns3_rl_err(netdev, "xmit error: %d!\n", ret);
@@ -1466,21 +1502,14 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
if (unlikely(ret < 0))
goto fill_err;

+ /* 'ret < 0' means filling error, 'ret == 0' means skb->len is
+ * zero, which is unlikely, and 'ret > 0' means how many tx desc
+ * need to be notified to the hw.
+ */
ret = hns3_fill_skb_to_desc(ring, skb, DESC_TYPE_SKB);
- if (unlikely(ret < 0))
+ if (unlikely(ret <= 0))
goto fill_err;

- bd_num += ret;
-
- skb_walk_frags(skb, frag_skb) {
- ret = hns3_fill_skb_to_desc(ring, frag_skb,
- DESC_TYPE_FRAGLIST_SKB);
- if (unlikely(ret < 0))
- goto fill_err;
-
- bd_num += ret;
- }
-
pre_ntu = ring->next_to_use ? (ring->next_to_use - 1) :
(ring->desc_num - 1);
ring->desc[pre_ntu].tx.bdtp_fe_sc_vld_ra_ri |=
@@ -1491,7 +1520,7 @@ netdev_tx_t hns3_nic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
dev_queue = netdev_get_tx_queue(netdev, ring->queue_index);
doorbell = __netdev_tx_sent_queue(dev_queue, skb->len,
netdev_xmit_more());
- hns3_tx_doorbell(ring, bd_num, doorbell);
+ hns3_tx_doorbell(ring, ret, doorbell);

return NETDEV_TX_OK;

@@ -1656,11 +1685,15 @@ static void hns3_nic_get_stats64(struct net_device *netdev,
tx_drop += ring->stats.tx_l4_proto_err;
tx_drop += ring->stats.tx_l2l3l4_err;
tx_drop += ring->stats.tx_tso_err;
+ tx_drop += ring->stats.over_max_recursion;
+ tx_drop += ring->stats.hw_limitation;
tx_errors += ring->stats.sw_err_cnt;
tx_errors += ring->stats.tx_vlan_err;
tx_errors += ring->stats.tx_l4_proto_err;
tx_errors += ring->stats.tx_l2l3l4_err;
tx_errors += ring->stats.tx_tso_err;
+ tx_errors += ring->stats.over_max_recursion;
+ tx_errors += ring->stats.hw_limitation;
} while (u64_stats_fetch_retry_irq(&ring->syncp, start));

/* fetch the rx stats */
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
index 1c81dea0da1e..398686b15a82 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
@@ -359,6 +359,8 @@ struct ring_stats {
u64 tx_l4_proto_err;
u64 tx_l2l3l4_err;
u64 tx_tso_err;
+ u64 over_max_recursion;
+ u64 hw_limitation;
};
struct {
u64 rx_pkts;
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c b/drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c
index 6b07b2771172..c0aa3be0cdfb 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c
@@ -39,6 +39,8 @@ static const struct hns3_stats hns3_txq_stats[] = {
HNS3_TQP_STAT("l4_proto_err", tx_l4_proto_err),
HNS3_TQP_STAT("l2l3l4_err", tx_l2l3l4_err),
HNS3_TQP_STAT("tso_err", tx_tso_err),
+ HNS3_TQP_STAT("over_max_recursion", over_max_recursion),
+ HNS3_TQP_STAT("hw_limitation", hw_limitation),
};

#define HNS3_TXQ_STATS_COUNT ARRAY_SIZE(hns3_txq_stats)
--
2.30.2