kvm: no need to check return value of debugfs_create functions

Message ID 20180529162204.11757-1-gregkh@linuxfoundation.org
State Accepted
Headers show
Series
  • kvm: no need to check return value of debugfs_create functions
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Commit Message

Greg Kroah-Hartman May 29, 2018, 4:22 p.m.
When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

This cleans up the error handling a lot, as this code will never get
hit.

Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: kvmarm@lists.cs.columbia.edu
Cc: kvm@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/powerpc/kvm/book3s_hv.c   |  3 +--
 virt/kvm/arm/vgic/vgic-debug.c | 17 ++++-----------
 virt/kvm/arm/vgic/vgic.h       |  4 ++--
 virt/kvm/kvm_main.c            | 40 +++++++---------------------------
 4 files changed, 15 insertions(+), 49 deletions(-)

Comments

Paolo Bonzini May 29, 2018, 5:06 p.m. | #1
On 29/05/2018 18:22, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.
> 
> This cleans up the error handling a lot, as this code will never get
> hit.
> 
> Cc: Paul Mackerras <paulus@ozlabs.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christoffer Dall <christoffer.dall@arm.com>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Andre Przywara <andre.przywara@arm.com>
> Cc: kvm-ppc@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: kvmarm@lists.cs.columbia.edu
> Cc: kvm@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  arch/powerpc/kvm/book3s_hv.c   |  3 +--
>  virt/kvm/arm/vgic/vgic-debug.c | 17 ++++-----------
>  virt/kvm/arm/vgic/vgic.h       |  4 ++--
>  virt/kvm/kvm_main.c            | 40 +++++++---------------------------
>  4 files changed, 15 insertions(+), 49 deletions(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 4d07fca5121c..67d7de1470cc 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -3950,8 +3950,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
>  	 */
>  	snprintf(buf, sizeof(buf), "vm%d", current->pid);
>  	kvm->arch.debugfs_dir = debugfs_create_dir(buf, kvm_debugfs_dir);
> -	if (!IS_ERR_OR_NULL(kvm->arch.debugfs_dir))
> -		kvmppc_mmu_debugfs_init(kvm);
> +	kvmppc_mmu_debugfs_init(kvm);
>  
>  	return 0;
>  }
> diff --git a/virt/kvm/arm/vgic/vgic-debug.c b/virt/kvm/arm/vgic/vgic-debug.c
> index 10b38178cff2..0140b29079b6 100644
> --- a/virt/kvm/arm/vgic/vgic-debug.c
> +++ b/virt/kvm/arm/vgic/vgic-debug.c
> @@ -263,21 +263,12 @@ static const struct file_operations vgic_debug_fops = {
>  	.release = seq_release
>  };
>  
> -int vgic_debug_init(struct kvm *kvm)
> +void vgic_debug_init(struct kvm *kvm)
>  {
> -	if (!kvm->debugfs_dentry)
> -		return -ENOENT;
> -
> -	if (!debugfs_create_file("vgic-state", 0444,
> -				 kvm->debugfs_dentry,
> -				 kvm,
> -				 &vgic_debug_fops))
> -		return -ENOMEM;
> -
> -	return 0;
> +	debugfs_create_file("vgic-state", 0444, kvm->debugfs_dentry, kvm,
> +			    &vgic_debug_fops);
>  }
>  
> -int vgic_debug_destroy(struct kvm *kvm)
> +void vgic_debug_destroy(struct kvm *kvm)
>  {
> -	return 0;
>  }
> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
> index 830e815748a0..3c38c5349953 100644
> --- a/virt/kvm/arm/vgic/vgic.h
> +++ b/virt/kvm/arm/vgic/vgic.h
> @@ -229,8 +229,8 @@ void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);
>  int vgic_lazy_init(struct kvm *kvm);
>  int vgic_init(struct kvm *kvm);
>  
> -int vgic_debug_init(struct kvm *kvm);
> -int vgic_debug_destroy(struct kvm *kvm);
> +void vgic_debug_init(struct kvm *kvm);
> +void vgic_debug_destroy(struct kvm *kvm);
>  
>  bool lock_all_vcpus(struct kvm *kvm);
>  void unlock_all_vcpus(struct kvm *kvm);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index c7b2e927f699..0ad400f353fc 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -572,10 +572,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
>  		return 0;
>  
>  	snprintf(dir_name, sizeof(dir_name), "%d-%d", task_pid_nr(current), fd);
> -	kvm->debugfs_dentry = debugfs_create_dir(dir_name,
> -						 kvm_debugfs_dir);
> -	if (!kvm->debugfs_dentry)
> -		return -ENOMEM;
> +	kvm->debugfs_dentry = debugfs_create_dir(dir_name, kvm_debugfs_dir);
>  
>  	kvm->debugfs_stat_data = kcalloc(kvm_debugfs_num_entries,
>  					 sizeof(*kvm->debugfs_stat_data),
> @@ -591,11 +588,8 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
>  		stat_data->kvm = kvm;
>  		stat_data->offset = p->offset;
>  		kvm->debugfs_stat_data[p - debugfs_entries] = stat_data;
> -		if (!debugfs_create_file(p->name, 0644,
> -					 kvm->debugfs_dentry,
> -					 stat_data,
> -					 stat_fops_per_vm[p->kind]))
> -			return -ENOMEM;
> +		debugfs_create_file(p->name, 0644, kvm->debugfs_dentry,
> +				    stat_data, stat_fops_per_vm[p->kind]);
>  	}
>  	return 0;
>  }
> @@ -3896,29 +3890,18 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
>  	kfree(env);
>  }
>  
> -static int kvm_init_debug(void)
> +static void kvm_init_debug(void)
>  {
> -	int r = -EEXIST;
>  	struct kvm_stats_debugfs_item *p;
>  
>  	kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);
> -	if (kvm_debugfs_dir == NULL)
> -		goto out;
>  
>  	kvm_debugfs_num_entries = 0;
>  	for (p = debugfs_entries; p->name; ++p, kvm_debugfs_num_entries++) {
> -		if (!debugfs_create_file(p->name, 0644, kvm_debugfs_dir,
> -					 (void *)(long)p->offset,
> -					 stat_fops[p->kind]))
> -			goto out_dir;
> +		debugfs_create_file(p->name, 0644, kvm_debugfs_dir,
> +				    (void *)(long)p->offset,
> +				    stat_fops[p->kind]);
>  	}
> -
> -	return 0;
> -
> -out_dir:
> -	debugfs_remove_recursive(kvm_debugfs_dir);
> -out:
> -	return r;
>  }
>  
>  static int kvm_suspend(void)
> @@ -4046,20 +4029,13 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
>  	kvm_preempt_ops.sched_in = kvm_sched_in;
>  	kvm_preempt_ops.sched_out = kvm_sched_out;
>  
> -	r = kvm_init_debug();
> -	if (r) {
> -		pr_err("kvm: create debugfs files failed\n");
> -		goto out_undebugfs;
> -	}
> +	kvm_init_debug();
>  
>  	r = kvm_vfio_ops_init();
>  	WARN_ON(r);
>  
>  	return 0;
>  
> -out_undebugfs:
> -	unregister_syscore_ops(&kvm_syscore_ops);
> -	misc_deregister(&kvm_dev);
>  out_unreg:
>  	kvm_async_pf_deinit();
>  out_free:
> 

Queued, thanks.

Paolo
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Patch

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 4d07fca5121c..67d7de1470cc 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3950,8 +3950,7 @@  static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 	 */
 	snprintf(buf, sizeof(buf), "vm%d", current->pid);
 	kvm->arch.debugfs_dir = debugfs_create_dir(buf, kvm_debugfs_dir);
-	if (!IS_ERR_OR_NULL(kvm->arch.debugfs_dir))
-		kvmppc_mmu_debugfs_init(kvm);
+	kvmppc_mmu_debugfs_init(kvm);
 
 	return 0;
 }
diff --git a/virt/kvm/arm/vgic/vgic-debug.c b/virt/kvm/arm/vgic/vgic-debug.c
index 10b38178cff2..0140b29079b6 100644
--- a/virt/kvm/arm/vgic/vgic-debug.c
+++ b/virt/kvm/arm/vgic/vgic-debug.c
@@ -263,21 +263,12 @@  static const struct file_operations vgic_debug_fops = {
 	.release = seq_release
 };
 
-int vgic_debug_init(struct kvm *kvm)
+void vgic_debug_init(struct kvm *kvm)
 {
-	if (!kvm->debugfs_dentry)
-		return -ENOENT;
-
-	if (!debugfs_create_file("vgic-state", 0444,
-				 kvm->debugfs_dentry,
-				 kvm,
-				 &vgic_debug_fops))
-		return -ENOMEM;
-
-	return 0;
+	debugfs_create_file("vgic-state", 0444, kvm->debugfs_dentry, kvm,
+			    &vgic_debug_fops);
 }
 
-int vgic_debug_destroy(struct kvm *kvm)
+void vgic_debug_destroy(struct kvm *kvm)
 {
-	return 0;
 }
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index 830e815748a0..3c38c5349953 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -229,8 +229,8 @@  void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);
 int vgic_lazy_init(struct kvm *kvm);
 int vgic_init(struct kvm *kvm);
 
-int vgic_debug_init(struct kvm *kvm);
-int vgic_debug_destroy(struct kvm *kvm);
+void vgic_debug_init(struct kvm *kvm);
+void vgic_debug_destroy(struct kvm *kvm);
 
 bool lock_all_vcpus(struct kvm *kvm);
 void unlock_all_vcpus(struct kvm *kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c7b2e927f699..0ad400f353fc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -572,10 +572,7 @@  static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 		return 0;
 
 	snprintf(dir_name, sizeof(dir_name), "%d-%d", task_pid_nr(current), fd);
-	kvm->debugfs_dentry = debugfs_create_dir(dir_name,
-						 kvm_debugfs_dir);
-	if (!kvm->debugfs_dentry)
-		return -ENOMEM;
+	kvm->debugfs_dentry = debugfs_create_dir(dir_name, kvm_debugfs_dir);
 
 	kvm->debugfs_stat_data = kcalloc(kvm_debugfs_num_entries,
 					 sizeof(*kvm->debugfs_stat_data),
@@ -591,11 +588,8 @@  static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 		stat_data->kvm = kvm;
 		stat_data->offset = p->offset;
 		kvm->debugfs_stat_data[p - debugfs_entries] = stat_data;
-		if (!debugfs_create_file(p->name, 0644,
-					 kvm->debugfs_dentry,
-					 stat_data,
-					 stat_fops_per_vm[p->kind]))
-			return -ENOMEM;
+		debugfs_create_file(p->name, 0644, kvm->debugfs_dentry,
+				    stat_data, stat_fops_per_vm[p->kind]);
 	}
 	return 0;
 }
@@ -3896,29 +3890,18 @@  static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
 	kfree(env);
 }
 
-static int kvm_init_debug(void)
+static void kvm_init_debug(void)
 {
-	int r = -EEXIST;
 	struct kvm_stats_debugfs_item *p;
 
 	kvm_debugfs_dir = debugfs_create_dir("kvm", NULL);
-	if (kvm_debugfs_dir == NULL)
-		goto out;
 
 	kvm_debugfs_num_entries = 0;
 	for (p = debugfs_entries; p->name; ++p, kvm_debugfs_num_entries++) {
-		if (!debugfs_create_file(p->name, 0644, kvm_debugfs_dir,
-					 (void *)(long)p->offset,
-					 stat_fops[p->kind]))
-			goto out_dir;
+		debugfs_create_file(p->name, 0644, kvm_debugfs_dir,
+				    (void *)(long)p->offset,
+				    stat_fops[p->kind]);
 	}
-
-	return 0;
-
-out_dir:
-	debugfs_remove_recursive(kvm_debugfs_dir);
-out:
-	return r;
 }
 
 static int kvm_suspend(void)
@@ -4046,20 +4029,13 @@  int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
 	kvm_preempt_ops.sched_in = kvm_sched_in;
 	kvm_preempt_ops.sched_out = kvm_sched_out;
 
-	r = kvm_init_debug();
-	if (r) {
-		pr_err("kvm: create debugfs files failed\n");
-		goto out_undebugfs;
-	}
+	kvm_init_debug();
 
 	r = kvm_vfio_ops_init();
 	WARN_ON(r);
 
 	return 0;
 
-out_undebugfs:
-	unregister_syscore_ops(&kvm_syscore_ops);
-	misc_deregister(&kvm_dev);
 out_unreg:
 	kvm_async_pf_deinit();
 out_free: