The commit is pushed to "branch-rh7-3.10.0-1160.80.1.vz7.191.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git after rh7-3.10.0-1160.80.1.vz7.191.4 ------> commit 451e988eee7ac96b0075a15a09b9238f338c8e62 Author: Jakub Kicinski <k...@kernel.org> Date: Thu Aug 12 14:42:39 2021 -0700
rh/bnxt: don't lock the tx queue from napi poll We can't take the tx lock from the napi poll routine, because netpoll can poll napi at any moment, including with the tx lock already held. The tx lock is protecting against two paths - the disable path, and (as Michael points out) the NETDEV_TX_BUSY case which may occur if NAPI completions race with start_xmit and both decide to re-enable the queue. For the disable/ifdown path use synchronize_net() to make sure closing the device does not race we restarting the queues. Annotate accesses to dev_state against data races. For the NAPI cleanup vs start_xmit path - appropriate barriers are already in place in the main spot where Tx queue is stopped but we need to do the same careful dance in the TX_BUSY case. mFixes: c0c050c58d84 ("bnxt_en: New Broadcom ethernet driver.") Reviewed-by: Michael Chan <michael.c...@broadcom.com> Reviewed-by: Edwin Peer <edwin.p...@broadcom.com> Signed-off-by: Jakub Kicinski <k...@kernel.org> The patch is backported from RHEL7.9 kernel 3.10.0-1160.81.1.el7: https://access.redhat.com/labs/rhcb/RHEL-7.9/kernel-3.10.0-1160.81.1.el7/patches/blob/1499-netdrv-bnxt-don-t-lock-the-tx-queue-from-napi-poll.patch From: Jamie Bainbridge <jbain...@redhat.com> Date: Thu, 12 Aug 2021 14:42:39 -0700 Subject: [PATCH 1499/1510] [netdrv] bnxt: don't lock the tx queue from napi poll Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2110869 https://jira.sw.ru/browse/PSBM-144136 (cherry picked from ms commit 3c603136c9f82833813af77185618de5af67676c) Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com> --- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 54 ++++++++++++++++++------------- 1 file changed, 32 insertions(+), 22 deletions(-) diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c index 351ab994b773..328eef7b7ef2 100644 --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c @@ -340,6 +340,26 @@ static u16 bnxt_xmit_get_cfa_action(struct sk_buff *skb) return md_dst->u.port_info.port_id; } +static bool bnxt_txr_netif_try_stop_queue(struct bnxt *bp, + struct bnxt_tx_ring_info *txr, + struct netdev_queue *txq) +{ + netif_tx_stop_queue(txq); + + /* netif_tx_stop_queue() must be done before checking + * tx index in bnxt_tx_avail() below, because in + * bnxt_tx_int(), we update tx index before checking for + * netif_tx_queue_stopped(). + */ + smp_mb(); + if (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh) { + netif_tx_wake_queue(txq); + return false; + } + + return true; +} + static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) { struct bnxt *bp = netdev_priv(dev); @@ -367,8 +387,8 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) free_size = bnxt_tx_avail(bp, txr); if (unlikely(free_size < skb_shinfo(skb)->nr_frags + 2)) { - netif_tx_stop_queue(txq); - return NETDEV_TX_BUSY; + if (bnxt_txr_netif_try_stop_queue(bp, txr, txq)) + return NETDEV_TX_BUSY; } length = skb->len; @@ -579,16 +599,7 @@ static netdev_tx_t bnxt_start_xmit(struct sk_buff *skb, struct net_device *dev) if (skb->xmit_more && !tx_buf->is_push) bnxt_db_write(bp, &txr->tx_db, prod); - netif_tx_stop_queue(txq); - - /* netif_tx_stop_queue() must be done before checking - * tx index in bnxt_tx_avail() below, because in - * bnxt_tx_int(), we update tx index before checking for - * netif_tx_queue_stopped(). - */ - smp_mb(); - if (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh) - netif_tx_wake_queue(txq); + bnxt_txr_netif_try_stop_queue(bp, txr, txq); } return NETDEV_TX_OK; @@ -672,14 +683,9 @@ static void bnxt_tx_int(struct bnxt *bp, struct bnxt_napi *bnapi, int nr_pkts) smp_mb(); if (unlikely(netif_tx_queue_stopped(txq)) && - (bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh)) { - __netif_tx_lock(txq, smp_processor_id()); - if (netif_tx_queue_stopped(txq) && - bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh && - txr->dev_state != BNXT_DEV_STATE_CLOSING) - netif_tx_wake_queue(txq); - __netif_tx_unlock(txq); - } + bnxt_tx_avail(bp, txr) > bp->tx_wake_thresh && + READ_ONCE(txr->dev_state) != BNXT_DEV_STATE_CLOSING) + netif_tx_wake_queue(txq); } static struct page *__bnxt_alloc_rx_page(struct bnxt *bp, dma_addr_t *mapping, @@ -7791,9 +7797,11 @@ void bnxt_tx_disable(struct bnxt *bp) if (bp->tx_ring) { for (i = 0; i < bp->tx_nr_rings; i++) { txr = &bp->tx_ring[i]; - txr->dev_state = BNXT_DEV_STATE_CLOSING; + WRITE_ONCE(txr->dev_state, BNXT_DEV_STATE_CLOSING); } } + /* Make sure napi polls see @dev_state change */ + synchronize_net(); /* Drop carrier first to prevent TX timeout */ netif_carrier_off(bp->dev); /* Stop all TX queues */ @@ -7807,8 +7815,10 @@ void bnxt_tx_enable(struct bnxt *bp) for (i = 0; i < bp->tx_nr_rings; i++) { txr = &bp->tx_ring[i]; - txr->dev_state = 0; + WRITE_ONCE(txr->dev_state, 0); } + /* Make sure napi polls see @dev_state change */ + synchronize_net(); netif_tx_wake_all_queues(bp->dev); if (bp->link_info.link_up) netif_carrier_on(bp->dev); _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel