netdev - [PATCH 4/4] virtio-blk: Fix probe failed when modprobe virtio

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Message-ID: <20221128021005.232105-5-lizetao1@huawei.com>
Date:   Mon, 28 Nov 2022 10:10:05 +0800
From:   Li Zetao <lizetao1@...wei.com>
To:     <mst@...hat.com>, <jasowang@...hat.com>, <pbonzini@...hat.com>,
        <stefanha@...hat.com>, <axboe@...nel.dk>, <kraxel@...hat.com>,
        <david@...hat.com>, <ericvh@...il.com>, <lucho@...kov.net>,
        <asmadeus@...ewreck.org>, <linux_oss@...debyte.com>,
        <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <rusty@...tcorp.com.au>
CC:     <lizetao1@...wei.com>, <virtualization@...ts.linux-foundation.org>,
        <linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <v9fs-developer@...ts.sourceforge.net>, <netdev@...r.kernel.org>
Subject: [PATCH 4/4] virtio-blk: Fix probe failed when modprobe virtio_blk

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

  step 2: fault injection in __blk_mq_alloc_disk()
    # modprobe -r virtio_blk   <-- OK
    # ...
      CPU: 0 PID: 4578 Comm: modprobe Tainted: G        W
      6.1.0-rc6-00308-g644e9524388a-dirty
      Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
      Call Trace:
       <TASK>
       should_failslab+0xa/0x20
       ...
       blk_alloc_queue+0x3a4/0x780
       __blk_mq_alloc_disk+0x91/0x1f0
       virtblk_probe+0x6ff/0x1f20 [virtio_blk]
       ...
       </TASK>
      virtio_blk: probe of virtio1 failed with error -12

  step 3: modprobe virtio_net failed
    # modprobe virtio_blk       <-- failed
      virtio_blk: 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 __blk_mq_alloc_disk()
fails in virtblk_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
init_vq() succeeded, all virtqueues should be stopped on error
handling path.

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

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 19da5defd734..f401546d4e85 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -1157,6 +1157,7 @@ static int virtblk_probe(struct virtio_device *vdev)
 	put_disk(vblk->disk);
 out_free_tags:
 	blk_mq_free_tag_set(&vblk->tag_set);
+	virtio_reset_device(vdev);
 out_free_vq:
 	vdev->config->del_vqs(vdev);
 	kfree(vblk->vqs);
-- 
2.25.1