From 8ce568ed06ce4ca38c0b67d8de9b8d75b731f90a Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 21 Jun 2021 15:54:33 -0700 Subject: [PATCH] mptcp: drop tx skb cache The mentioned cache was introduced to reduce the number of skb allocation in atomic context, but the required complexity is excessive. This change remove the mentioned cache. Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 89 ++------------------------------------------ net/mptcp/protocol.h | 2 - 2 files changed, 4 insertions(+), 87 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index b5f2f504b85b..77c90d6f04df 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -902,22 +902,14 @@ static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk, df->data_seq + df->data_len == msk->write_seq; } -static int mptcp_wmem_with_overhead(struct sock *sk, int size) +static int mptcp_wmem_with_overhead(int size) { - struct mptcp_sock *msk = mptcp_sk(sk); - int ret, skbs; - - ret = size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT); - skbs = (msk->tx_pending_data + size) / msk->size_goal_cache; - if (skbs < msk->skb_tx_cache.qlen) - return ret; - - return ret + (skbs - msk->skb_tx_cache.qlen) * SKB_TRUESIZE(MAX_TCP_HEADER); + return size + ((sizeof(struct mptcp_data_frag) * size) >> PAGE_SHIFT); } static void __mptcp_wmem_reserve(struct sock *sk, int size) { - int amount = mptcp_wmem_with_overhead(sk, size); + int amount = mptcp_wmem_with_overhead(size); struct mptcp_sock *msk = mptcp_sk(sk); WARN_ON_ONCE(msk->wmem_reserved); @@ -1212,49 +1204,8 @@ static struct sk_buff *__mptcp_do_alloc_tx_skb(struct sock *sk, gfp_t gfp) return NULL; } -static bool mptcp_tx_cache_refill(struct sock *sk, int size, - struct sk_buff_head *skbs, int *total_ts) -{ - struct mptcp_sock *msk = mptcp_sk(sk); - struct sk_buff *skb; - int space_needed; - - if (unlikely(tcp_under_memory_pressure(sk))) { - mptcp_mem_reclaim_partial(sk); - - /* under pressure pre-allocate at most a single skb */ - if (msk->skb_tx_cache.qlen) - return true; - space_needed = msk->size_goal_cache; - } else { - space_needed = msk->tx_pending_data + size - - msk->skb_tx_cache.qlen * msk->size_goal_cache; - } - - while (space_needed > 0) { - skb = __mptcp_do_alloc_tx_skb(sk, sk->sk_allocation); - if (unlikely(!skb)) { - /* under memory pressure, try to pass the caller a - * single skb to allow forward progress - */ - while (skbs->qlen > 1) { - skb = __skb_dequeue_tail(skbs); - *total_ts -= skb->truesize; - __kfree_skb(skb); - } - return skbs->qlen > 0; - } - - *total_ts += skb->truesize; - __skb_queue_tail(skbs, skb); - space_needed -= msk->size_goal_cache; - } - return true; -} - static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp) { - struct mptcp_sock *msk = mptcp_sk(sk); struct sk_buff *skb; if (ssk->sk_tx_skb_cache) { @@ -1265,22 +1216,6 @@ static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp) return true; } - skb = skb_peek(&msk->skb_tx_cache); - if (skb) { - if (likely(sk_wmem_schedule(ssk, skb->truesize))) { - skb = __skb_dequeue(&msk->skb_tx_cache); - if (WARN_ON_ONCE(!skb)) - return false; - - mptcp_wmem_uncharge(sk, skb->truesize); - ssk->sk_tx_skb_cache = skb; - return true; - } - - /* over memory limit, no point to try to allocate a new skb */ - return false; - } - skb = __mptcp_do_alloc_tx_skb(sk, gfp); if (!skb) return false; @@ -1296,7 +1231,6 @@ static bool __mptcp_alloc_tx_skb(struct sock *sk, struct sock *ssk, gfp_t gfp) static bool mptcp_must_reclaim_memory(struct sock *sk, struct sock *ssk) { return !ssk->sk_tx_skb_cache && - !skb_peek(&mptcp_sk(sk)->skb_tx_cache) && tcp_under_memory_pressure(sk); } @@ -1339,7 +1273,6 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, /* compute send limit */ info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags); avail_size = info->size_goal; - msk->size_goal_cache = info->size_goal; skb = tcp_write_queue_tail(ssk); if (skb) { /* Limit the write to the size available in the @@ -1688,7 +1621,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) while (msg_data_left(msg)) { int total_ts, frag_truesize = 0; struct mptcp_data_frag *dfrag; - struct sk_buff_head skbs; bool dfrag_collapsed; size_t psize, offset; @@ -1721,16 +1653,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) psize = pfrag->size - offset; psize = min_t(size_t, psize, msg_data_left(msg)); total_ts = psize + frag_truesize; - __skb_queue_head_init(&skbs); - if (!mptcp_tx_cache_refill(sk, psize, &skbs, &total_ts)) - goto wait_for_memory; - if (!mptcp_wmem_alloc(sk, total_ts)) { - __skb_queue_purge(&skbs); + if (!mptcp_wmem_alloc(sk, total_ts)) goto wait_for_memory; - } - skb_queue_splice_tail(&skbs, &msk->skb_tx_cache); if (copy_page_from_iter(dfrag->page, offset, psize, &msg->msg_iter) != psize) { mptcp_wmem_uncharge(sk, psize + frag_truesize); @@ -2462,13 +2388,11 @@ static int __mptcp_init_sock(struct sock *sk) INIT_LIST_HEAD(&msk->rtx_queue); INIT_WORK(&msk->work, mptcp_worker); __skb_queue_head_init(&msk->receive_queue); - __skb_queue_head_init(&msk->skb_tx_cache); msk->out_of_order_queue = RB_ROOT; msk->first_pending = NULL; msk->wmem_reserved = 0; msk->rmem_released = 0; msk->tx_pending_data = 0; - msk->size_goal_cache = TCP_BASE_MSS; msk->ack_hint = NULL; msk->first = NULL; @@ -2525,15 +2449,10 @@ static void __mptcp_clear_xmit(struct sock *sk) { struct mptcp_sock *msk = mptcp_sk(sk); struct mptcp_data_frag *dtmp, *dfrag; - struct sk_buff *skb; WRITE_ONCE(msk->first_pending, NULL); list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) dfrag_clear(sk, dfrag); - while ((skb = __skb_dequeue(&msk->skb_tx_cache)) != NULL) { - sk->sk_forward_alloc += skb->truesize; - kfree_skb(skb); - } } static void mptcp_cancel_work(struct sock *sk) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 160d716ebc2b..160c2ab09f19 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -245,9 +245,7 @@ struct mptcp_sock { struct sk_buff *ooo_last_skb; struct rb_root out_of_order_queue; struct sk_buff_head receive_queue; - struct sk_buff_head skb_tx_cache; /* this is wmem accounted */ int tx_pending_data; - int size_goal_cache; struct list_head conn_list; struct list_head rtx_queue; struct mptcp_data_frag *first_pending; -- GitLab