Messages in this thread | | | Subject | Re: [PATCH] s390/vfio-ap: do not use open locks during VFIO_GROUP_NOTIFY_SET_KVM notification | From | Tony Krowiak <> | Date | Mon, 28 Jun 2021 14:27:26 -0400 |
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On 6/28/21 2:22 PM, Jason Gunthorpe wrote: > On Mon, Jun 28, 2021 at 02:20:55PM -0400, Tony Krowiak wrote: >> >> On 6/28/21 1:34 PM, Jason Gunthorpe wrote: >>> On Fri, Jun 25, 2021 at 06:07:58PM -0400, Tony Krowiak wrote: >>>> static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev) >>>> { >>>> + mutex_lock(&matrix_dev->lock); >>>> + if ((matrix_mdev->kvm) && (matrix_mdev->kvm->arch.crypto.crycbd)) { >>>> mutex_unlock(&matrix_dev->lock); >>>> + down_write(&matrix_mdev->kvm->arch.crypto.pqap_hook_rwsem); >>>> + matrix_mdev->kvm->arch.crypto.pqap_hook = NULL; >>>> + up_write(&matrix_mdev->kvm->arch.crypto.pqap_hook_rwsem); >>>> + kvm_arch_crypto_clear_masks(matrix_mdev->kvm); >>>> mutex_lock(&matrix_dev->lock); >>>> vfio_ap_mdev_reset_queues(matrix_mdev->mdev); >>>> kvm_put_kvm(matrix_mdev->kvm); >>>> matrix_mdev->kvm = NULL; >>>> + mutex_unlock(&matrix_dev->lock); >>>> } >>> Doesn't a flow exit the function with matrix_dev->lock held he
Yes, you are correct. Stupid mistake.
>> How can that happen? What flow? > When the if isn't taken > >>> Write it with 'success oriented flow' >> I'm not sure what you mean, can you clarify this statement? > Basically, don't write the bulk of the function under an if statement > > mutex_lock(&matrix_dev->lock); > if (!matrix_mdev->kvm || !matrix_mdev->kvm->arch.crypto.crycbd) { > mutex_unlock(&matrix_dev->lock); > return; > }
Sure.
> > Jason >
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