> vscsi->num_queues counts the number of request virtqueue which does not
> include the control and event virtqueue. It is wrong to subtract
> VIRTIO_SCSI_VQ_BASE from vscsi->num_queues.
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> This patch fixes the following panic.
>
> (qemu) device_del scsi0
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
> IP: [<ffffffff8179b29f>] __virtscsi_set_affinity+0x6f/0x120
> PGD 0
> Oops: 0000 [#1] SMP
> Modules linked in:
> CPU: 0 PID: 659 Comm: kworker/0:1 Not tainted 3.11.0-rc2+ #1172
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> Workqueue: kacpi_hotplug _handle_hotplug_event_func
> task: ffff88007bee1cc0 ti: ffff88007bfe4000 task.ti: ffff88007bfe4000
> RIP: 0010:[<ffffffff8179b29f>] [<ffffffff8179b29f>]
> __virtscsi_set_affinity+0x6f/0x120
> RSP: 0018:ffff88007bfe5a38 EFLAGS: 00010202
> RAX: 0000000000000010 RBX: ffff880077fd0d28 RCX: 0000000000000050
> RDX: 0000000000000000 RSI: 0000000000000246 RDI: 0000000000000000
> RBP: ffff88007bfe5a58 R08: ffff880077f6ff00 R09: 0000000000000001
> R10: ffffffff8143e673 R11: 0000000000000001 R12: 0000000000000001
> R13: ffff880077fd0800 R14: 0000000000000000 R15: ffff88007bf489b0
> FS: 0000000000000000(0000) GS:ffff88007ea00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000020 CR3: 0000000079f8b000 CR4: 00000000000006f0
> Stack:
> ffff880077fd0d28 0000000000000000 ffff880077fd0800 0000000000000008
> ffff88007bfe5a78 ffffffff8179b37d ffff88007bccc800 ffff88007bccc800
> ffff88007bfe5a98 ffffffff8179b3b6 ffff88007bccc800 ffff880077fd0d28
> Call Trace:
> [<ffffffff8179b37d>] virtscsi_set_affinity+0x2d/0x40
> [<ffffffff8179b3b6>] virtscsi_remove_vqs+0x26/0x50
> [<ffffffff8179c7d2>] virtscsi_remove+0x82/0xa0
> [<ffffffff814cb6b2>] virtio_dev_remove+0x22/0x70
> [<ffffffff8167ca49>] __device_release_driver+0x69/0xd0
> [<ffffffff8167cb9d>] device_release_driver+0x2d/0x40
> [<ffffffff8167bb96>] bus_remove_device+0x116/0x150
> [<ffffffff81679936>] device_del+0x126/0x1e0
> [<ffffffff81679a06>] device_unregister+0x16/0x30
> [<ffffffff814cb889>] unregister_virtio_device+0x19/0x30
> [<ffffffff814cdad6>] virtio_pci_remove+0x36/0x80
> [<ffffffff81464ae7>] pci_device_remove+0x37/0x70
> [<ffffffff8167ca49>] __device_release_driver+0x69/0xd0
> [<ffffffff8167cb9d>] device_release_driver+0x2d/0x40
> [<ffffffff8167bb96>] bus_remove_device+0x116/0x150
> [<ffffffff81679936>] device_del+0x126/0x1e0
> [<ffffffff8145edfc>] pci_stop_bus_device+0x9c/0xb0
> [<ffffffff8145f036>] pci_stop_and_remove_bus_device+0x16/0x30
> [<ffffffff81474a9e>] acpiphp_disable_slot+0x8e/0x150
> [<ffffffff81474f6a>] hotplug_event_func+0xba/0x1a0
> [<ffffffff814906c8>] ? acpi_os_release_object+0xe/0x12
> [<ffffffff81475911>] _handle_hotplug_event_func+0x31/0x70
> [<ffffffff810b5333>] process_one_work+0x183/0x500
> [<ffffffff810b66e2>] worker_thread+0x122/0x400
> [<ffffffff810b65c0>] ? manage_workers+0x2d0/0x2d0
> [<ffffffff810bc5de>] kthread+0xce/0xe0
> [<ffffffff810bc510>] ? kthread_freezable_should_stop+0x70/0x70
> [<ffffffff81ca045c>] ret_from_fork+0x7c/0xb0
> [<ffffffff810bc510>] ? kthread_freezable_should_stop+0x70/0x70
> Code: 01 00 00 00 74 59 45 31 e4 83 bb c8 01 00 00 02 74 46 66 2e 0f 1f 84
> 00 00 00 00 00 49 63 c4 48 c1 e0 04 48 8b bc 0
> 3 10 02 00 00 <48> 8b 47 20 48 8b 80 d0 01 00 00 48 8b 40 50 48 85 c0 74 07
> be
> RIP [<ffffffff8179b29f>] __virtscsi_set_affinity+0x6f/0x120
> RSP <ffff88007bfe5a38>
> CR2: 0000000000000020
> ---[ end trace 99679331a3775f48 ]---
>
> CC: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Asias He <asias@xxxxxxxxxx>
> ---
> drivers/scsi/virtio_scsi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
> index 2168258..74b88ef 100644
> --- a/drivers/scsi/virtio_scsi.c
> +++ b/drivers/scsi/virtio_scsi.c
> @@ -751,7 +751,7 @@ static void __virtscsi_set_affinity(struct virtio_scsi
> *vscsi, bool affinity)
>
> vscsi->affinity_hint_set = true;
> } else {
> - for (i = 0; i < vscsi->num_queues - VIRTIO_SCSI_VQ_BASE; i++)
> + for (i = 0; i < vscsi->num_queues; i++)
> virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1);
>
> vscsi->affinity_hint_set = false;
> --
> 1.8.3.1
>
>
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