netdev - [PATCH] virtio_net: Fix oops on early interrupts

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Message-Id: <200802111411.15745.borntraeger@de.ibm.com>
Date:	Mon, 11 Feb 2008 14:11:15 +0100
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Avi Kivity <avi@...ranet.com>
Cc:	dor.laor@...ranet.com, Anthony Liguori <aliguori@...ibm.com>,
	"kvm-devel" <kvm-devel@...ts.sourceforge.net>,
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org
Subject: [PATCH] virtio_net: Fix oops on early interrupts - introduced by virtio reset code

Avi,
this fixes a problem that was introduced by the virtio_reset patches. 
Can you apply that fix to kvm.git as a bugfix,  as the virtio_reset
infrastructure is not on Linus upstream yet?

Anthony, Dor,
are you ok with that change?

--

With the latest virtio_reset patches I got the following oops:

Unable to handle kernel pointer dereference at virtual kernel address 0000000000000000
Oops: 0004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 Not tainted 2.6.24zlive-guest-10577-g63f5307-dirty #168
Process swapper (pid: 0, task: 000000000f866040, ksp: 000000000f86fd78)
Krnl PSW : 0404100180000000 000000000047598a (skb_recv_done+0x52/0x98)
           R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:1 PM:0 EA:3
Krnl GPRS: 0000000000000001 0000000000000000 000000000efd0e60 0000000000000001
           0000000000000000 000000000f866040 0000000000000000 0000000000000000
           00000000008de4c8 0000000000001237 0000000000001237 000000000f977dd8
           0000000000000020 00000000001132bc 000000000f977e08 000000000f977dd8
Krnl Code: 000000000047597c: e31040300004       lg      %r1,48(%r4)
           0000000000475982: b9040001           lgr     %r0,%r1
           0000000000475986: b9810003           ogr     %r0,%r3
          >000000000047598a: eb1040300030       csg     %r1,%r0,48(%r4)
           0000000000475990: a744fff9           brc     4,475982
           0000000000475994: a7110001           tmll    %r1,1
           0000000000475998: a7840009           brc     8,4759aa
           000000000047599c: e340b0b80004       lg      %r4,184(%r11)
Call Trace:
([<000001500f978000>] 0x1500f978000)
 [<00000000004779a6>] vring_interrupt+0x72/0x88
 [<0000000000491d9c>] kvm_extint_handler+0x34/0x44
 [<000000000010d2d4>] do_extint+0xc0/0xfc
 [<0000000000113b5a>] ext_no_vtime+0x1c/0x20
 [<000000000010a0b6>] cpu_idle+0x21a/0x230


We must initialize vdev->priv before we use the notify hypercall as 
vdev->priv is used in skb_recv_done. So lets move the assignment of 
vdev->priv before we call try_fill_recv.

Signed-off-by: Christian Borntraeger <borntraeger@...ibm.com>
---
 drivers/net/virtio_net.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: kvm/drivers/net/virtio_net.c
===================================================================
--- kvm.orig/drivers/net/virtio_net.c
+++ kvm/drivers/net/virtio_net.c
@@ -361,6 +361,7 @@ static int virtnet_probe(struct virtio_d
 	netif_napi_add(dev, &vi->napi, virtnet_poll, napi_weight);
 	vi->dev = dev;
 	vi->vdev = vdev;
+	vdev->priv = vi;
 
 	/* We expect two virtqueues, receive then send. */
 	vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done);
@@ -395,7 +396,6 @@ static int virtnet_probe(struct virtio_d
 	}
 
 	pr_debug("virtnet: registered device %s\n", dev->name);
-	vdev->priv = vi;
 	return 0;
 
 unregister:
--
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