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    SubjectRe: [PATCH] x86: KVM, fix lock imbalance
    On 07/07/2010 03:05 PM, Ingo Molnar wrote:
    >
    > * Jiri Slaby <jirislaby@gmail.com> wrote:
    >
    >> Stanse found that there is an omitted unlock in kvm_create_pit in one fail
    >> path. Add proper unlock there.
    >>
    >> Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
    >> Cc: Avi Kivity <avi@redhat.com>
    >> Cc: Marcelo Tosatti <mtosatti@redhat.com>
    >> Cc: Thomas Gleixner <tglx@linutronix.de>
    >> Cc: Ingo Molnar <mingo@redhat.com>
    >> Cc: "H. Peter Anvin" <hpa@zytor.com>
    >> Cc: x86@kernel.org
    >> Cc: Gleb Natapov <gleb@redhat.com>
    >> Cc: "Michael S. Tsirkin" <mst@redhat.com>
    >> Cc: Gregory Haskins <ghaskins@novell.com>
    >> Cc: kvm@vger.kernel.org
    >> ---
    >> arch/x86/kvm/i8254.c | 1 +
    >> 1 files changed, 1 insertions(+), 0 deletions(-)
    >>
    >> diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
    >> index 467cc47..70db4d4 100644
    >> --- a/arch/x86/kvm/i8254.c
    >> +++ b/arch/x86/kvm/i8254.c
    >> @@ -696,6 +696,7 @@ struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags)
    >>
    >> pit->wq = create_singlethread_workqueue("kvm-pit-wq");
    >> if (!pit->wq) {
    >> + mutex_unlock(&pit->pit_state.lock);
    >> kfree(pit);
    >> return NULL;
    >> }
    >
    > A cleanliness comment: why is that tear-down/dealloc sequence open-coded? It
    > should be at the end of the function, with goto labels, like we do it in
    > similar cases.

    Because the lock is around a block only. I usually don't create a goto
    fail-paths in these cases. Do you want one?

    thanks,
    --
    js


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