From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtOyN5LXmbFfntk/Mai9a60NP67aHv3fER4zKVFG7cePA+4AWQlZLpidEEAPMhZHmEuPvbF ARC-Seal: i=1; a=rsa-sha256; t=1521214683; cv=none; d=google.com; s=arc-20160816; b=dYAxvNUKisGaoHDMriyica7fc5k5pxT0oI358+dh1yeEIxrkK3+8ZpAFTLfmsTXbrO qR7OJoQLq+0um9TfDgYDLFNlSjs7JCr9PJ4p1aXUIqLkMhwZuJSOJK1eypqBjU8bA4Re sCGX7mJA5w3TwPiC1ADuxVhgrYskjBN28i9bBM32WALBPLqCBZeITIhTIx3xpirEFY1j 0WCq27GlDuGHvIjHhsaG9XaOEnVNzHlOEvXqGYJYfcIU+6g+7lVXWdj/FCQ2EvPn5b76 0QJB5DxcDAeHWmNXukxyzSAXuoR+/EgxlCLXNHIbFUW3tUGiE+3j3XT8y/QoFWmJZhSM 0JeA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=5PEtK9Uj8hiBeM64O6TtgfPSVdQdNAnRVNoLdQb1F1Y=; b=QOgi3LYjNbsmgq9Yk4BCAU0InGsrozOzAno3Ppp8qbmluSlOAGMur6WLJSm6x/Gi6V TRSc5iTX+VKY0AzlgXRj0bDH/iCZjOrcSc50910lem+SoyAAicYO5JCO9rruR9zuslK/ WrfZtmNhtUo4GQbvnMiAqMZ3x4cx8BwuXPeN0uUDlS+7aGrmnSVKLYZaDm4kuwZY84gu yzTxXJF3NiboY8BRcgKhsF9evoSzaJe8D4px5wrNqgNivjMLIzr9XJ9Aplo1SEyD5DUP daojO+yWgusHQ8V7DiwSF0yAohHmXM5VQjCuKO7PfZm2YblpV2dctmeJTLeRyVH7dmsb Cbdw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Fastabend , "David S. Miller" , Sasha Levin Subject: [PATCH 4.14 090/109] net: sched: drop qdisc_reset from dev_graft_qdisc Date: Fri, 16 Mar 2018 16:23:59 +0100 Message-Id: <20180316152334.821254067@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180316152329.844663293@linuxfoundation.org> References: <20180316152329.844663293@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1595109207660390965?= X-GMAIL-MSGID: =?utf-8?q?1595109207660390965?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: John Fastabend [ Upstream commit 7bbde83b1860c28a1cc35516352c4e7e5172c29a ] In qdisc_graft_qdisc a "new" qdisc is attached and the 'qdisc_destroy' operation is called on the old qdisc. The destroy operation will wait a rcu grace period and call qdisc_rcu_free(). At which point gso_cpu_skb is free'd along with all stats so no need to zero stats and gso_cpu_skb from the graft operation itself. Further after dropping the qdisc locks we can not continue to call qdisc_reset before waiting an rcu grace period so that the qdisc is detached from all cpus. By removing the qdisc_reset() here we get the correct property of waiting an rcu grace period and letting the qdisc_destroy operation clean up the qdisc correctly. Note, a refcnt greater than 1 would cause the destroy operation to be aborted however if this ever happened the reference to the qdisc would be lost and we would have a memory leak. Signed-off-by: John Fastabend Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_generic.c | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -743,10 +743,6 @@ struct Qdisc *dev_graft_qdisc(struct net root_lock = qdisc_lock(oqdisc); spin_lock_bh(root_lock); - /* Prune old scheduler */ - if (oqdisc && refcount_read(&oqdisc->refcnt) <= 1) - qdisc_reset(oqdisc); - /* ... and graft new one */ if (qdisc == NULL) qdisc = &noop_qdisc; @@ -897,6 +893,16 @@ static bool some_qdisc_is_busy(struct ne return false; } +static void dev_qdisc_reset(struct net_device *dev, + struct netdev_queue *dev_queue, + void *none) +{ + struct Qdisc *qdisc = dev_queue->qdisc_sleeping; + + if (qdisc) + qdisc_reset(qdisc); +} + /** * dev_deactivate_many - deactivate transmissions on several devices * @head: list of devices to deactivate @@ -907,7 +913,6 @@ static bool some_qdisc_is_busy(struct ne void dev_deactivate_many(struct list_head *head) { struct net_device *dev; - bool sync_needed = false; list_for_each_entry(dev, head, close_list) { netdev_for_each_tx_queue(dev, dev_deactivate_queue, @@ -917,20 +922,25 @@ void dev_deactivate_many(struct list_hea &noop_qdisc); dev_watchdog_down(dev); - sync_needed |= !dev->dismantle; } /* Wait for outstanding qdisc-less dev_queue_xmit calls. * This is avoided if all devices are in dismantle phase : * Caller will call synchronize_net() for us */ - if (sync_needed) - synchronize_net(); + synchronize_net(); /* Wait for outstanding qdisc_run calls. */ - list_for_each_entry(dev, head, close_list) + list_for_each_entry(dev, head, close_list) { while (some_qdisc_is_busy(dev)) yield(); + /* The new qdisc is assigned at this point so we can safely + * unwind stale skb lists and qdisc statistics + */ + netdev_for_each_tx_queue(dev, dev_qdisc_reset, NULL); + if (dev_ingress_queue(dev)) + dev_qdisc_reset(dev, dev_ingress_queue(dev), NULL); + } } void dev_deactivate(struct net_device *dev)