Commit 0b22bd0b authored Oct 22, 2009 by Michael S. Tsirkin Committed by Rusty Russell Oct 29, 2009

virtio-pci: fix per-vq MSI-X request logic



Commit f68d2408
in 2.6.32-rc1 broke requesting IRQs for per-VQ MSI-X vectors:
- vector number was used instead of the vector itself
- we try to request an IRQ for VQ which does not
  have a callback handler

This is a regression that causes warnings in kernel log,
potentially lower performance as we need to scan vq list,
and might cause system failure if the interrupt
requested is in fact needed by another system.

This was not noticed earlier because in most cases
we were falling back on shared interrupt for all vqs.

The warnings often look like this:

virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 28 for MSI/MSI-X
IRQ handler type mismatch for IRQ 1
current handler: i8042
Pid: 2400, comm: modprobe Tainted: G        W
2.6.32-rc3-11952-gf3ed8d8-dirty #1
Call Trace:
 [<ffffffff81072aed>] ? __setup_irq+0x299/0x304
 [<ffffffff81072ff3>] ? request_threaded_irq+0x144/0x1c1
 [<ffffffff813455af>] ? vring_interrupt+0x0/0x30
 [<ffffffff81346598>] ? vp_try_to_find_vqs+0x583/0x5c7
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffff81346609>] ? vp_find_vqs+0x2d/0x83
 [<ffffffff81345d00>] ? vp_get+0x3c/0x4e
 [<ffffffffa0016373>] ? virtnet_probe+0x2f1/0x428 [virtio_net]
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffffa00150d8>] ? skb_xmit_done+0x0/0x39 [virtio_net]
 [<ffffffff8110ab92>] ? sysfs_do_create_link+0xcb/0x116
 [<ffffffff81345cc2>] ? vp_get_status+0x14/0x16
 [<ffffffff81345464>] ? virtio_dev_probe+0xa9/0xc8
 [<ffffffff8122b11c>] ? driver_probe_device+0x8d/0x128
 [<ffffffff8122b206>] ? __driver_attach+0x4f/0x6f
 [<ffffffff8122b1b7>] ? __driver_attach+0x0/0x6f
 [<ffffffff8122a9f9>] ? bus_for_each_dev+0x43/0x74
 [<ffffffff8122a374>] ? bus_add_driver+0xea/0x22d
 [<ffffffff8122b4a3>] ? driver_register+0xa7/0x111
 [<ffffffffa001a000>] ? init+0x0/0xc [virtio_net]
 [<ffffffff81009051>] ? do_one_initcall+0x50/0x148
 [<ffffffff8106e117>] ? sys_init_module+0xc5/0x21a
 [<ffffffff8100af02>] ? system_call_fastpath+0x16/0x1b
virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X

Reported-by: Marcelo Tosatti <mtosatti@redhat.com>
Reported-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

parent 964fe080

drivers/virtio/virtio_pci.c

+15 −12

Original line number	Original line	Diff line number	Diff line
	@@ -530,13 +530,17 @@ static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs,
	err = PTR_ERR(vqs[i]);		err = PTR_ERR(vqs[i]);
	goto error_find;		goto error_find;
	}		}

			if (!vp_dev->per_vq_vectors \|\| msix_vec == VIRTIO_MSI_NO_VECTOR)
			continue;

	/* allocate per-vq irq if available and necessary */		/* allocate per-vq irq if available and necessary */
	if (vp_dev->per_vq_vectors) {
	snprintf(vp_dev->msix_names[msix_vec],		snprintf(vp_dev->msix_names[msix_vec],
	sizeof *vp_dev->msix_names,		sizeof *vp_dev->msix_names,
	"%s-%s",		"%s-%s",
	dev_name(&vp_dev->vdev.dev), names[i]);		dev_name(&vp_dev->vdev.dev), names[i]);
	err = request_irq(msix_vec, vring_interrupt, 0,		err = request_irq(vp_dev->msix_entries[msix_vec].vector,
			vring_interrupt, 0,
	vp_dev->msix_names[msix_vec],		vp_dev->msix_names[msix_vec],
	vqs[i]);		vqs[i]);
	if (err) {		if (err) {
	@@ -544,7 +548,6 @@ static int vp_try_to_find_vqs(struct virtio_device *vdev, unsigned nvqs,
	goto error_find;		goto error_find;
	}		}
	}		}
	}
	return 0;		return 0;

	error_find:		error_find:

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