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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, Somnath Kotur <somnath.kotur@broadcom.com>,
        Pavan Chebbi <pavan.chebbi@broadcom.com>,
        Andy Gospodarek <gospo@broadcom.com>,
        Michael Chan <michael.chan@broadcom.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 109/171] bnxt_en: reserve space inside receive page for skb_shared_info
Date:   Tue, 12 Apr 2022 08:30:00 +0200
Message-Id: <20220412062931.038115167@linuxfoundation.org>
In-Reply-To: <20220412062927.870347203@linuxfoundation.org>
References: <20220412062927.870347203@linuxfoundation.org>
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From: Andy Gospodarek <gospo@broadcom.com>

[ Upstream commit facc173cf700e55b2ad249ecbd3a7537f7315691 ]

Insufficient space was being reserved in the page used for packet
reception, so the interface MTU could be set too large to still have
room for the contents of the packet when doing XDP redirect.  This
resulted in the following message when redirecting a packet between
3520 and 3822 bytes with an MTU of 3822:

[311815.561880] XDP_WARN: xdp_update_frame_from_buff(line:200): Driver BUG: missing reserved tailroom

Fixes: f18c2b77b2e4 ("bnxt_en: optimized XDP_REDIRECT support")
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 92f9f7f5240b..34affd1de91d 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -569,7 +569,8 @@ struct nqe_cn {
 #define BNXT_MAX_MTU		9500
 #define BNXT_MAX_PAGE_MODE_MTU	\
 	((unsigned int)PAGE_SIZE - VLAN_ETH_HLEN - NET_IP_ALIGN -	\
-	 XDP_PACKET_HEADROOM)
+	 XDP_PACKET_HEADROOM - \
+	 SKB_DATA_ALIGN((unsigned int)sizeof(struct skb_shared_info)))
 
 #define BNXT_MIN_PKT_SIZE	52
 
-- 
2.35.1