[PATCH] KVM: PPC: Book3S HV: add of_node_put() in success path

[PATCH] KVM: PPC: Book3S HV: add of_node_put() in success path

[Nicholas Mc Guire]

 The call to of_find_compatible_node() is returning a pointer with
incremented refcount so it must be explicitly decremented after the
last use. As here it is only being used for checking of node presence
but the result is not actually used in the success path it can be
dropped immediately.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Fixes: commit f725758b899f ("KVM: PPC: Book3S HV: Use OPAL XICS emulation on POWER9")
---
Problem found by experimental coccinelle script

Patch was compiletested with: ppc64_defconfig (implies CONFIG_KVM=y,
CONFIG_KVM_BOOK3S_64_HV=m)
with many sparse warnings though not related to the proposed change

Patch is against 4.18-rc3 (localversion-next is next-20180705)

 arch/powerpc/kvm/book3s_hv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index ee4a885..8680fb9 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4561,6 +4561,8 @@ static int kvmppc_book3s_init_hv(void)
 			pr_err("KVM-HV: Cannot determine method for accessing XICS\n");
 			return -ENODEV;
 		}
+		/* presence of intc confirmed - node can be dropped again */
+		of_node_put(np);
 	}
 #endif
 
-- 
2.1.4

Re: [PATCH] KVM: PPC: Book3S HV: add of_node_put() in success path

[Paul Mackerras]

On Sat, Jul 07, 2018 at 08:53:07AM +0200, Nicholas Mc Guire wrote:
>  The call to of_find_compatible_node() is returning a pointer with
> incremented refcount so it must be explicitly decremented after the
> last use. As here it is only being used for checking of node presence
> but the result is not actually used in the success path it can be
> dropped immediately.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> Fixes: commit f725758b899f ("KVM: PPC: Book3S HV: Use OPAL XICS emulation on POWER9")

Thanks, patch applied to my kvm-ppc-next branch.

Paul.