linux-kernel - Re: [PATCH 03/11] KVM: PPC: Book3S HV: Move error code assignments in two functions

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Date:   Mon, 23 Jan 2017 15:13:12 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        kvm@...r.kernel.org, kvm-ppc@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, Alexander Graf <agraf@...e.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 03/11] KVM: PPC: Book3S HV: Move error code assignments in
 two functions



On 20/01/2017 19:21, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Fri, 20 Jan 2017 10:30:26 +0100
> 
> A local variable was set to an error code in a few cases before a concrete
> error situation was detected. Thus move the corresponding assignments into
> if branches to indicate a software failure there.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  arch/powerpc/kvm/book3s_hv.c | 25 +++++++++++++++----------
>  1 file changed, 15 insertions(+), 10 deletions(-)

NACK, current code uses consistent style.

Paolo

> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 8dcbe37a4dac..a93e1c4445da 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -2967,15 +2967,17 @@ static int kvm_vm_ioctl_get_dirty_log_hv(struct kvm *kvm,
>  
>  	mutex_lock(&kvm->slots_lock);
>  
> -	r = -EINVAL;
> -	if (log->slot >= KVM_USER_MEM_SLOTS)
> +	if (log->slot >= KVM_USER_MEM_SLOTS) {
> +		r = -EINVAL;
>  		goto out;
> +	}
>  
>  	slots = kvm_memslots(kvm);
>  	memslot = id_to_memslot(slots, log->slot);
> -	r = -ENOENT;
> -	if (!memslot->dirty_bitmap)
> +	if (!memslot->dirty_bitmap) {
> +		r = -ENOENT;
>  		goto out;
> +	}
>  
>  	n = kvm_dirty_bitmap_bytes(memslot);
>  	memset(memslot->dirty_bitmap, 0, n);
> @@ -2984,9 +2986,10 @@ static int kvm_vm_ioctl_get_dirty_log_hv(struct kvm *kvm,
>  	if (r)
>  		goto out;
>  
> -	r = -EFAULT;
> -	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
> +	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n)) {
> +		r = -EFAULT;
>  		goto out;
> +	}
>  
>  	r = 0;
>  out:
> @@ -3127,9 +3130,10 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu)
>  	memslot = gfn_to_memslot(kvm, 0);
>  
>  	/* We must have some memory at 0 by now */
> -	err = -EINVAL;
> -	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
> +	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
> +		err = -EINVAL;
>  		goto out_srcu;
> +	}
>  
>  	/* Look up the VMA for the start of this memory slot */
>  	hva = memslot->userspace_addr;
> @@ -3144,10 +3148,11 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu)
>  	up_read(&current->mm->mmap_sem);
>  
>  	/* We can handle 4k, 64k or 16M pages in the VRMA */
> -	err = -EINVAL;
>  	if (!(psize == 0x1000 || psize == 0x10000 ||
> -	      psize == 0x1000000))
> +	      psize == 0x1000000)) {
> +		err = -EINVAL;
>  		goto out_srcu;
> +	}
>  
>  	senc = slb_pgsize_encoding(psize);
>  	kvm->arch.vrma_slb_v = senc | SLB_VSID_B_1T |
>