Messages in this thread | | | From | Minfei Huang <> | Date | Tue, 19 Jul 2016 00:18:32 +0800 | Subject | Re: [PATCH v2] virtio_blk: Fix a slient kernel panic |
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On 07/18/16 at 05:21P, Cornelia Huck wrote: > On Mon, 18 Jul 2016 22:01:29 +0800 > Minfei Huang <mnfhuang@gmail.com> wrote: > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > > index 42758b5..d920512 100644 > > --- a/drivers/block/virtio_blk.c > > +++ b/drivers/block/virtio_blk.c > > @@ -381,9 +381,9 @@ static int init_vq(struct virtio_blk *vblk) > > { > > int err = 0; > > int i; > > - vq_callback_t **callbacks; > > - const char **names; > > - struct virtqueue **vqs; > > + vq_callback_t **callbacks = NULL; > > + const char **names = NULL; > > + struct virtqueue **vqs = NULL; > > If you init the variables to NULL anyway...
Hi, Cornelia.
Thanks for reviewing this patch.
Seems there is no need to init these variables to NULL. I will remove them laster.
> > > unsigned short num_vqs; > > struct virtio_device *vdev = vblk->vdev; > > > > @@ -394,22 +394,16 @@ static int init_vq(struct virtio_blk *vblk) > > num_vqs = 1; > > > > ...just do > > err = -ENOMEM; > > here and... > > > vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL); > > - if (!vblk->vqs) { > > - err = -ENOMEM; > > - goto out; > > - } > > + if (!vblk->vqs) > > + return -ENOMEM; > > > > names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL); > > - if (!names) > > - goto err_names; > > - > > callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL); > > - if (!callbacks) > > - goto err_callbacks; > > - > > vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL); > > - if (!vqs) > > - goto err_vqs; > > + if (!names || !callbacks || !vqs) { > > + err = -ENOMEM; > > + goto out; > > + } > > ...you could use the > > foo = kmalloc(...); > if (!foo) > goto out; > > sequence in any case. This avoids trying again and again if e.g. the > names allocation already failed.
For this implementation, I have referred others which calls vdev->config->find_vqs as well. Yes, this continues trying to allocate memory, although memory allocation failed before.
> > Alternatively, you should be fine if you don't init the variables to > NULL: The code is now either taking an early exit or setting all of the > variables anyway. >
It's a big change if we refactor the helper ->find_vqs, since other devices also call it.
Thanks Minfei
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