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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,
        Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.19 019/139] net: thunderx: set xdp_prog to NULL if bpf_prog_add fails
Date:   Tue,  4 Dec 2018 11:48:20 +0100
Message-Id: <20181204103650.768788031@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>

[ Upstream commit 6d0f60b0f8588fd4380ea5df9601e12fddd55ce2 ]

Set xdp_prog pointer to NULL if bpf_prog_add fails since that routine
reports the error code instead of NULL in case of failure and xdp_prog
pointer value is used in the driver to verify if XDP is currently
enabled.
Moreover report the error code to userspace if nicvf_xdp_setup fails

Fixes: 05c773f52b96 ("net: thunderx: Add basic XDP support")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/cavium/thunder/nicvf_main.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
@@ -1784,6 +1784,7 @@ static int nicvf_xdp_setup(struct nicvf
 	bool if_up = netif_running(nic->netdev);
 	struct bpf_prog *old_prog;
 	bool bpf_attached = false;
+	int ret = 0;
 
 	/* For now just support only the usual MTU sized frames */
 	if (prog && (dev->mtu > 1500)) {
@@ -1817,8 +1818,12 @@ static int nicvf_xdp_setup(struct nicvf
 	if (nic->xdp_prog) {
 		/* Attach BPF program */
 		nic->xdp_prog = bpf_prog_add(nic->xdp_prog, nic->rx_queues - 1);
-		if (!IS_ERR(nic->xdp_prog))
+		if (!IS_ERR(nic->xdp_prog)) {
 			bpf_attached = true;
+		} else {
+			ret = PTR_ERR(nic->xdp_prog);
+			nic->xdp_prog = NULL;
+		}
 	}
 
 	/* Calculate Tx queues needed for XDP and network stack */
@@ -1830,7 +1835,7 @@ static int nicvf_xdp_setup(struct nicvf
 		netif_trans_update(nic->netdev);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int nicvf_xdp(struct net_device *netdev, struct netdev_bpf *xdp)