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    Subject[PATCH 2/4] virtio_blk: Less function calls in init_vq() after error detection
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    From: Markus Elfring <elfring@users.sourceforge.net>
    Date: Tue, 13 Sep 2016 13:20:44 +0200

    The kfree() function was called in up to three cases
    by the init_vq() function during error handling even if
    the passed variable contained a null pointer.

    * Split a condition check for memory allocation failures.

    * Adjust jump targets according to the Linux coding style convention.

    Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
    ---
    drivers/block/virtio_blk.c | 22 +++++++++++++++++-----
    1 file changed, 17 insertions(+), 5 deletions(-)

    diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
    index 6553eb7..d28dbcf 100644
    --- a/drivers/block/virtio_blk.c
    +++ b/drivers/block/virtio_blk.c
    @@ -395,11 +395,21 @@ static int init_vq(struct virtio_blk *vblk)
    return -ENOMEM;

    names = kmalloc_array(num_vqs, sizeof(*names), GFP_KERNEL);
    + if (!names) {
    + err = -ENOMEM;
    + goto free_vblk_vqs;
    + }
    +
    callbacks = kmalloc_array(num_vqs, sizeof(*callbacks), GFP_KERNEL);
    + if (!callbacks) {
    + err = -ENOMEM;
    + goto free_names;
    + }
    +
    vqs = kmalloc_array(num_vqs, sizeof(*vqs), GFP_KERNEL);
    - if (!names || !callbacks || !vqs) {
    + if (!vqs) {
    err = -ENOMEM;
    - goto out;
    + goto free_callbacks;
    }

    for (i = 0; i < num_vqs; i++) {
    @@ -411,19 +421,21 @@ static int init_vq(struct virtio_blk *vblk)
    /* Discover virtqueues and write information to configuration. */
    err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
    if (err)
    - goto out;
    + goto free_vqs;

    for (i = 0; i < num_vqs; i++) {
    spin_lock_init(&vblk->vqs[i].lock);
    vblk->vqs[i].vq = vqs[i];
    }
    vblk->num_vqs = num_vqs;
    -
    -out:
    + free_vqs:
    kfree(vqs);
    + free_callbacks:
    kfree(callbacks);
    + free_names:
    kfree(names);
    if (err)
    + free_vblk_vqs:
    kfree(vblk->vqs);
    return err;
    }
    --
    2.10.0
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