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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Maurice Baijens <maurice.baijens@ellips.com>,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        Sandeep Penigalapati <sandeep.penigalapati@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 5.4 39/64] ixgbe: xsk: change !netif_carrier_ok() handling in ixgbe_xmit_zc()
Date:   Mon,  7 Mar 2022 10:19:12 +0100
Message-Id: <20220307091640.256636889@linuxfoundation.org>
In-Reply-To: <20220307091639.136830784@linuxfoundation.org>
References: <20220307091639.136830784@linuxfoundation.org>
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From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

commit 6c7273a266759d9d36f7c862149f248bcdeddc0f upstream.

Commit c685c69fba71 ("ixgbe: don't do any AF_XDP zero-copy transmit if
netif is not OK") addressed the ring transient state when
MEM_TYPE_XSK_BUFF_POOL was being configured which in turn caused the
interface to through down/up. Maurice reported that when carrier is not
ok and xsk_pool is present on ring pair, ksoftirqd will consume 100% CPU
cycles due to the constant NAPI rescheduling as ixgbe_poll() states that
there is still some work to be done.

To fix this, do not set work_done to false for a !netif_carrier_ok().

Fixes: c685c69fba71 ("ixgbe: don't do any AF_XDP zero-copy transmit if netif is not OK")
Reported-by: Maurice Baijens <maurice.baijens@ellips.com>
Tested-by: Maurice Baijens <maurice.baijens@ellips.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -583,12 +583,14 @@ static bool ixgbe_xmit_zc(struct ixgbe_r
 	u32 cmd_type;
 
 	while (budget-- > 0) {
-		if (unlikely(!ixgbe_desc_unused(xdp_ring)) ||
-		    !netif_carrier_ok(xdp_ring->netdev)) {
+		if (unlikely(!ixgbe_desc_unused(xdp_ring))) {
 			work_done = false;
 			break;
 		}
 
+		if (!netif_carrier_ok(xdp_ring->netdev))
+			break;
+
 		if (!xsk_umem_consume_tx(xdp_ring->xsk_umem, &desc))
 			break;