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    Subject[PATCH 5.15 621/917] powerpc: fix unbalanced node refcount in check_kvm_guest()
    Date
    From: Nathan Lynch <nathanl@linux.ibm.com>

    [ Upstream commit 56537faf8821e361d739fc5ff58c9c40f54a1d4c ]

    When check_kvm_guest() succeeds in looking up a /hypervisor OF node, it
    returns without performing a matching put for the lookup, leaving the
    node's reference count elevated.

    Add the necessary call to of_node_put(), rearranging the code slightly to
    avoid repetition or goto.

    Fixes: 107c55005fbd ("powerpc/pseries: Add KVM guest doorbell restrictions")
    Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
    Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
    Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/20210928124550.132020-1-nathanl@linux.ibm.com
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/powerpc/kernel/firmware.c | 7 +++----
    1 file changed, 3 insertions(+), 4 deletions(-)

    diff --git a/arch/powerpc/kernel/firmware.c b/arch/powerpc/kernel/firmware.c
    index c7022c41cc314..20328f72f9f2b 100644
    --- a/arch/powerpc/kernel/firmware.c
    +++ b/arch/powerpc/kernel/firmware.c
    @@ -31,11 +31,10 @@ int __init check_kvm_guest(void)
    if (!hyper_node)
    return 0;

    - if (!of_device_is_compatible(hyper_node, "linux,kvm"))
    - return 0;
    -
    - static_branch_enable(&kvm_guest);
    + if (of_device_is_compatible(hyper_node, "linux,kvm"))
    + static_branch_enable(&kvm_guest);

    + of_node_put(hyper_node);
    return 0;
    }
    core_initcall(check_kvm_guest); // before kvm_guest_init()
    --
    2.33.0


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