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[bionic:linux-azure,3/3] hv_netvsc: Fix XDP refcnt for synthetic and VF NICs

Message ID 20200623173215.346858-4-marcelo.cerri@canonical.com
State New
Headers show
Series LP:#1877654 - Add XDP support to hv_netvsc driver | expand

Commit Message

Marcelo Henrique Cerri June 23, 2020, 5:32 p.m. UTC 
From: Haiyang Zhang <haiyangz@microsoft.com>

BugLink: https://bugs.launchpad.net/bugs/1877654

The caller of XDP_SETUP_PROG has already incremented refcnt in
__bpf_prog_get(), so drivers should only increment refcnt by
num_queues - 1.

To fix the issue, update netvsc_xdp_set() to add the correct number
to refcnt.

Hold a refcnt in netvsc_xdp_set()’s other caller, netvsc_attach().

And, do the same in netvsc_vf_setxdp(). Otherwise, every time when VF is
removed and added from the host side, the refcnt will be decreased by one,
which may cause page fault when unloading xdp program.

Fixes: 351e1581395f ("hv_netvsc: Add XDP support")
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 184367dce4f744bde54377203305ccc8889aa79f)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
---
 drivers/net/hyperv/netvsc_bpf.c | 13 +++++++++++--
 drivers/net/hyperv/netvsc_drv.c |  5 ++++-
 2 files changed, 15 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/hyperv/netvsc_bpf.c b/drivers/net/hyperv/netvsc_bpf.c
index 20adfe544294..b86611041db6 100644
--- a/drivers/net/hyperv/netvsc_bpf.c
+++ b/drivers/net/hyperv/netvsc_bpf.c
@@ -120,7 +120,7 @@  int netvsc_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 	}
 
 	if (prog)
-		bpf_prog_add(prog, nvdev->num_chn);
+		bpf_prog_add(prog, nvdev->num_chn - 1);
 
 	for (i = 0; i < nvdev->num_chn; i++)
 		rcu_assign_pointer(nvdev->chan_table[i].bpf_prog, prog);
@@ -136,6 +136,7 @@  int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog)
 {
 	struct netdev_bpf xdp;
 	bpf_op_t ndo_bpf;
+	int ret;
 
 	ASSERT_RTNL();
 
@@ -148,10 +149,18 @@  int netvsc_vf_setxdp(struct net_device *vf_netdev, struct bpf_prog *prog)
 
 	memset(&xdp, 0, sizeof(xdp));
 
+	if (prog)
+		bpf_prog_inc(prog);
+
 	xdp.command = XDP_SETUP_PROG;
 	xdp.prog = prog;
 
-	return ndo_bpf(vf_netdev, &xdp);
+	ret = ndo_bpf(vf_netdev, &xdp);
+
+	if (ret && prog)
+		bpf_prog_put(prog);
+
+	return ret;
 }
 
 static u32 netvsc_xdp_query(struct netvsc_device *nvdev)
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index a33b088fda24..9aebae66821d 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -1055,9 +1055,12 @@  static int netvsc_attach(struct net_device *ndev,
 
 	prog = dev_info->bprog;
 	if (prog) {
+		bpf_prog_inc(prog);
 		ret = netvsc_xdp_set(ndev, prog, NULL, nvdev);
-		if (ret)
+		if (ret) {
+			bpf_prog_put(prog);
 			goto err1;
+		}
 	}
 
 	/* In any case device is now ready */