From nobody Wed Mar 16 23:40:16 2022 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id D05F01A13C8C; Wed, 16 Mar 2022 23:40:16 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4KJmwc5TJrz4ksc; Wed, 16 Mar 2022 23:40:16 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1647474016; 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=xIUCKgO+T7j0JjoTOBFWRnsSceyCqb/Kevmx4nql9vw=; b=cXnYGScJmD2YW28kFblidSlhKOJrjbxde/eJgTukg5LmTr0/MlSNrpo5z1t1fGhfMrIF/H 3lY8xbGMuIoSTeXAKzV0T8OQWqWKfJcYRdnKqfDDwATl+4fLitGVhe/QUF4kKhnOWlXc9N Y3v17+FBv1jxHHbvr2N108PWerCPB6XXFZgE3gmfzqg3o5+o4lDso5Lsd85Lz3IbUa0Ay5 otBJywxkVJUtDYVlHnFOIwEnAJWTIPCv3Zm044262HpnaHCUYd6E1K/LfCmwabqm+ce96d dD+UUE2OwzuKbcfJtAWHQplIi2GLbYvXxBpIIDQnzS8gYEwzE7+amglbaH9wUA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 9C1D91F76A; Wed, 16 Mar 2022 23:40:16 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 22GNeGMj053475; Wed, 16 Mar 2022 23:40:16 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 22GNeGMO053469; Wed, 16 Mar 2022 23:40:16 GMT (envelope-from git) Date: Wed, 16 Mar 2022 23:40:16 GMT Message-Id: <202203162340.22GNeGMO053469@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Kristof Provost Subject: git: bb9ad300f029 - stable/13 - if_epair: fix race condition on multi-core systems List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-all@freebsd.org X-BeenThere: dev-commits-src-all@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: kp X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: bb9ad300f029d57c84804702daa2652542a2535f Auto-Submitted: auto-generated ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1647474016; 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=xIUCKgO+T7j0JjoTOBFWRnsSceyCqb/Kevmx4nql9vw=; b=lSIIT3l0TOvGePC2pHV5RQxZOAdTDlphTiLikrRklnx6/hY0Z7sVmma/9d94r/N/DTAUl2 /xUFOCJwvtgH7R2BDsPEVqcSpF5oIttwHhVZRFE70YPzMJormQv85F97IIO4A6W+8j0u/R rJ2MowRTQpNA7jlfI3NJ7q5eYPZaLXB/x5w8kXdQ1iMe6XnjzphjwP/E9emUckGh834jDL OwLFpPEJexaNBkzn0cipVKt+XxX20EnjEiV9cWj2oJ57eRvf+HyHdCi37S7ABcVkUcmDjD BAupFh6RSvTb+Nf6xCb1XFbb22wcXXiy6C8cG8FCAUn6p06vAm647fzDHlHbZg== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1647474016; a=rsa-sha256; cv=none; b=J4amG0EAjmX8FyVpF6MYLQfJAOhCfU5cDg1fZkS4ECgYKUQF4XtdR8LE9uHZ69ujKle+kN DsfWuSgnV75RhlH/MeQdWBXZVg2lRmwt9T7QSSWhgiL/cy+RJLOwLW6HHDqDpODhKZxv++ q6EhoM50KjUBNznx7eHM7nZYArttXO+Tn/ZxxQw2q9vosr3ym6r/Vj/tfsGtSaypXXJv00 fEbm6KQHmq2GYbdnr61nrwyQWWzgS19n/B/rAltDtMfrf/4iTM/G0qv5GttuleTCb342oV a4AhiT3to+NSbv1PPwPA/4YUbTFxJhKogOpW9MKkS7h+HmNxFZvLM6ARxg5byA== ARC-Authentication-Results: i=1; mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N The branch stable/13 has been updated by kp: URL: https://cgit.FreeBSD.org/src/commit/?id=bb9ad300f029d57c84804702daa2652542a2535f commit bb9ad300f029d57c84804702daa2652542a2535f Author: Michael Gmelin AuthorDate: 2022-03-16 22:08:55 +0000 Commit: Kristof Provost CommitDate: 2022-03-16 23:38:33 +0000 if_epair: fix race condition on multi-core systems As an unwanted side effect of the performance improvements in 24f0bfbad57b9, epair interfaces stop forwarding traffic on higher load levels when running on multi-core systems. This happens due to a race condition in the logic that decides when to place work in the task queue(s) responsible for processing the content of ring buffers. In order to fix this, a field named state is added to the epair_queue structure. This field is used by the affected functions to signal each other that something happened in the underlying ring buffers that might require work to be scheduled in task queue(s), replacing the existing logic, which relied on checking if ring buffers are empty or not. epair_menq() does: - set BIT_MBUF_QUEUED - queue mbuf - if testandset BIT_QUEUE_TASK: enqueue task epair_tx_start_deferred() does: - swap ring buffers - process mbufs - clear BIT_QUEUE_TASK - if testandclear BIT_MBUF_QUEUED enqueue task PR: 262571 Approved by: re (gjb, early MFC) Reported by: Johan Hendriks MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D34569 (cherry picked from commit 66acf7685bcd8cf23b6c658a991637238a01859e) --- sys/net/if_epair.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/sys/net/if_epair.c b/sys/net/if_epair.c index 6a77f44ffe87..d8f51c951913 100644 --- a/sys/net/if_epair.c +++ b/sys/net/if_epair.c @@ -104,11 +104,15 @@ static unsigned int next_index = 0; #define EPAIR_LOCK() mtx_lock(&epair_n_index_mtx) #define EPAIR_UNLOCK() mtx_unlock(&epair_n_index_mtx) +#define BIT_QUEUE_TASK 0 +#define BIT_MBUF_QUEUED 1 + struct epair_softc; struct epair_queue { int id; struct buf_ring *rxring[2]; volatile int ridx; /* 0 || 1 */ + volatile int state; /* taskqueue coordination */ struct task tx_task; struct epair_softc *sc; }; @@ -177,7 +181,8 @@ epair_tx_start_deferred(void *arg, int pending) } while (!atomic_fcmpset_int(&q->ridx, &ridx, nidx)); epair_if_input(sc, q, ridx); - if (! buf_ring_empty(q->rxring[nidx])) + atomic_clear_int(&q->state, (1 << BIT_QUEUE_TASK)); + if (atomic_testandclear_int(&q->state, BIT_MBUF_QUEUED)) taskqueue_enqueue(epair_tasks.tq[q->id], &q->tx_task); if_rele(sc->ifp); @@ -192,7 +197,6 @@ epair_menq(struct mbuf *m, struct epair_softc *osc) short mflags; struct epair_queue *q = NULL; uint32_t bucket; - bool was_empty; #ifdef RSS struct ether_header *eh; #endif @@ -244,14 +248,14 @@ epair_menq(struct mbuf *m, struct epair_softc *osc) #endif q = &osc->queues[bucket]; + atomic_set_int(&q->state, (1 << BIT_MBUF_QUEUED)); ridx = atomic_load_int(&q->ridx); - was_empty = buf_ring_empty(q->rxring[ridx]); ret = buf_ring_enqueue(q->rxring[ridx], m); if (ret != 0) { /* Ring is full. */ if_inc_counter(ifp, IFCOUNTER_OQDROPS, 1); m_freem(m); - goto done; + return (0); } if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1); @@ -266,8 +270,7 @@ epair_menq(struct mbuf *m, struct epair_softc *osc) /* Someone else received the packet. */ if_inc_counter(oifp, IFCOUNTER_IPACKETS, 1); -done: - if (was_empty) + if (!atomic_testandset_int(&q->state, BIT_QUEUE_TASK)) taskqueue_enqueue(epair_tasks.tq[bucket], &q->tx_task); return (0); @@ -548,6 +551,7 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params) q->rxring[0] = buf_ring_alloc(RXRSIZE, M_EPAIR, M_WAITOK, NULL); q->rxring[1] = buf_ring_alloc(RXRSIZE, M_EPAIR, M_WAITOK, NULL); q->ridx = 0; + q->state = 0; q->sc = sca; NET_TASK_INIT(&q->tx_task, 0, epair_tx_start_deferred, q); } @@ -570,6 +574,7 @@ epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params) q->rxring[0] = buf_ring_alloc(RXRSIZE, M_EPAIR, M_WAITOK, NULL); q->rxring[1] = buf_ring_alloc(RXRSIZE, M_EPAIR, M_WAITOK, NULL); q->ridx = 0; + q->state = 0; q->sc = scb; NET_TASK_INIT(&q->tx_task, 0, epair_tx_start_deferred, q); }