Re: [PATCH v3 6/6] KVM: Hoist debugfs_dentry init to kvm_create_vm_debugfs() (again)

Sean Christopherson
2022-08-05T19:02:28Z

On Wed, Jul 20, 2022, Oliver Upton wrote:
> From: Oliver Upton <oupton@google.com>
>
> Since KVM now sanely handles debugfs init/destroy w.r.t. the VM, it is
> safe to hoist kvm_create_vm_debugfs() back into kvm_create_vm(). The
> author of this commit remains bitter for having been burned by the old
> wreck in commit a44a4cc1c969 ("KVM: Don't create VM debugfs files
> outside of the VM directory").
>
> Signed-off-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Sean Christopherson <seanjc@google.com>

Heh, so this amusingly has my review, but I'd rather omit this patch and leave
the initialization with the pile of other code that initializes fields for which
zero-initialization is insufficient/incorrect.

Any objections to dropping this?

> ---
> virt/kvm/kvm_main.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 609f49a133f8..7ac60f75cfa1 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1032,6 +1032,12 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, const char *fdname)
> int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
> kvm_vcpu_stats_header.num_desc;
>
> + /*
> + * Force subsequent debugfs file creations to fail if the VM directory
> + * is not created.
> + */
> + kvm->debugfs_dentry = ERR_PTR(-ENOENT);
> +
> if (!debugfs_initialized())
> return 0;
>
> @@ -1154,12 +1160,6 @@ static struct kvm *kvm_create_vm(unsigned long type, const char *fdname)
>
> BUILD_BUG_ON(KVM_MEM_SLOTS_NUM > SHRT_MAX);
>
> - /*
> - * Force subsequent debugfs file creations to fail if the VM directory
> - * is not created (by kvm_create_vm_debugfs()).
> - */
> - kvm->debugfs_dentry = ERR_PTR(-ENOENT);
> -
> snprintf(kvm->stats_id, sizeof(kvm->stats_id), "kvm-%d",
> task_pid_nr(current));
>
> --
> 2.37.0.170.g444d1eabd0-goog
>