[PATCH 3/4] virtio-input: Fix probe failed when modprobe virtio_input

[Li Zetao]

When doing the following test steps, an error was found:
  step 1: modprobe virtio_input succeeded
    # modprobe virtio_input      <-- OK

  step 2: fault injection in input_allocate_device()
    # modprobe -r virtio_input   <-- OK
    # ...
      CPU: 0 PID: 4260 Comm: modprobe Tainted: G        W
      6.1.0-rc6-00285-g6a1e40c4b995-dirty #109
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
      Call Trace:
       <TASK>
       should_fail.cold+0x5/0x1f
       ...
       kmalloc_trace+0x27/0xa0
       input_allocate_device+0x43/0x280
       virtinput_probe+0x23b/0x1648 [virtio_input]
       ...
       </TASK>
      virtio_input: probe of virtio5 failed with error -12

  step 3: modprobe virtio_net failed
    # modprobe virtio_input       <-- failed
      virtio_input: probe of virtio1 failed with error -2

The root cause of the problem is that the virtqueues are not
stopped on the error handling path when input_allocate_device()
fails in virtinput_probe(), resulting in an error "-ENOENT"
returned in the next modprobe call in setup_vq().

virtio_pci_modern_device uses virtqueues to send or
receive message, and "queue_enable" records whether the
queues are available. In vp_modern_find_vqs(), all queues
will be selected and activated, but once queues are enabled
there is no way to go back except reset.

Fix it by reset virtio device on error handling path. After
virtinput_init_vqs() succeeded, all virtqueues should be
stopped on error handling path.

Fixes: 1fcf0512c9c8 ("virtio_pci: modern driver")
Signed-off-by: Li Zetao <lizetao1@xxxxxxxxxx>
---
 drivers/virtio/virtio_input.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
index 3aa46703872d..f638f1cd3531 100644
--- a/drivers/virtio/virtio_input.c
+++ b/drivers/virtio/virtio_input.c
@@ -330,6 +330,7 @@ static int virtinput_probe(struct virtio_device *vdev)
 err_mt_init_slots:
 	input_free_device(vi->idev);
 err_input_alloc:
+	virtio_reset_device(vdev);
 	vdev->config->del_vqs(vdev);
 err_init_vq:
 	kfree(vi);
-- 
2.25.1