From patchwork Fri May 21 10:30:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 12272873 X-Patchwork-Delegate: mat@martineau.name Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F50B71 for ; Fri, 21 May 2021 10:30:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621593014; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=9ZWS5/taKH+y61UrpYld5dZjtXmLnEcw1oZNHcRXjrg=; b=OZR+aGmrGURECloBUbdLyWhuwj176eaZg+T8aHhpuVC92Xek3F3FgQd7tFVDQXdSziOb+v NNJyZMggPwZPAsRi91Gm6/JVSPEZ32GlTIYxLP4BtBeUAcNmr8P2gzD4m+KvuYfwof5f5P VVriqjCmP+zfTcGtLm9XHNFi3urqlNU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-106-28ztsxTEO0WCmGnNYxbjrQ-1; Fri, 21 May 2021 06:30:12 -0400 X-MC-Unique: 28ztsxTEO0WCmGnNYxbjrQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCC3C1853DB1 for ; Fri, 21 May 2021 10:30:11 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-114-152.ams2.redhat.com [10.36.114.152]) by smtp.corp.redhat.com (Postfix) with ESMTP id 525E969FB1 for ; Fri, 21 May 2021 10:30:11 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next] mptcp: drop tx skb cache Date: Fri, 21 May 2021 12:30:07 +0200 Message-Id: X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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 --- formally submitting this one. I keept a VM running self-tests for ~24h with no issues --- net/mptcp/protocol.c | 89 ++------------------------------------------ 1 file changed, 4 insertions(+), 85 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 446acfb85493..1114a914d845 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -903,22 +903,14 @@ 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); @@ -1213,49 +1205,8 @@ 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) { @@ -1266,22 +1217,6 @@ 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; @@ -1297,7 +1232,6 @@ 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); } @@ -1340,7 +1274,6 @@ 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 @@ -1689,7 +1622,6 @@ 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; @@ -1722,16 +1654,10 @@ 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); @@ -2460,13 +2386,11 @@ 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; @@ -2527,15 +2451,10 @@ 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)