[PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code - Kernel

This is a discussion on [PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code - Kernel ; From: Julia Lawall There is a call to local_irq_restore in the normal exit case, so it would seem that there should be one on an error return as well. The semantic patch that makes this change is as follows: ( ...

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Thread: [PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code

  1. [PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code

    From: Julia Lawall

    There is a call to local_irq_restore in the normal exit case, so it would
    seem that there should be one on an error return as well.

    The semantic patch that makes this change is as follows:
    (http://www.emn.fr/x-info/coccinelle/)

    //
    @@
    expression l;
    expression E,E1,E2;
    @@

    local_irq_save(l);
    .... when != local_irq_restore(l)
    when != spin_unlock_irqrestore(E,l)
    when any
    when strict
    (
    if (...) { ... when != local_irq_restore(l)
    when != spin_unlock_irqrestore(E1,l)
    + local_irq_restore(l);
    return ...;
    }
    |
    if (...)
    + {local_irq_restore(l);
    return ...;
    + }
    |
    spin_unlock_irqrestore(E2,l);
    |
    local_irq_restore(l);
    )
    //


    Signed-off-by: Julia Lawall

    ---
    arch/ia64/kvm/kvm-ia64.c | 9 +++++++--
    1 files changed, 7 insertions(+), 2 deletions(-)

    diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
    index 318b811..14e5c99 100644
    --- a/arch/ia64/kvm/kvm-ia64.c
    +++ b/arch/ia64/kvm/kvm-ia64.c
    @@ -125,8 +125,10 @@ void kvm_arch_hardware_enable(void *garbage)
    PAGE_KERNEL));
    local_irq_save(saved_psr);
    slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
    - if (slot < 0)
    + if (slot < 0) {
    + local_irq_restore(saved_psr);
    return;
    + }
    local_irq_restore(saved_psr);

    spin_lock(&vp_lock);
    @@ -160,8 +162,10 @@ void kvm_arch_hardware_disable(void *garbage)

    local_irq_save(saved_psr);
    slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
    - if (slot < 0)
    + if (slot < 0) {
    + local_irq_restore(saved_psr);
    return;
    + }
    local_irq_restore(saved_psr);

    status = ia64_pal_vp_exit_env(host_iva);
    @@ -1258,6 +1262,7 @@ static int vti_vcpu_setup(struct kvm_vcpu *vcpu, int id)
    uninit:
    kvm_vcpu_uninit(vcpu);
    fail:
    + local_irq_restore(psr);
    return r;
    }

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  2. Re: [PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code

    tir, 22 07 2008 kl. 18:44 +0200, skrev Julia Lawall:
    > From: Julia Lawall
    >
    > There is a call to local_irq_restore in the normal exit case, so it would
    > seem that there should be one on an error return as well.
    >
    > The semantic patch that makes this change is as follows:
    > (http://www.emn.fr/x-info/coccinelle/)
    >
    > //
    > @@
    > expression l;
    > expression E,E1,E2;
    > @@
    >
    > local_irq_save(l);
    > ... when != local_irq_restore(l)
    > when != spin_unlock_irqrestore(E,l)
    > when any
    > when strict
    > (
    > if (...) { ... when != local_irq_restore(l)
    > when != spin_unlock_irqrestore(E1,l)
    > + local_irq_restore(l);
    > return ...;
    > }
    > |
    > if (...)
    > + {local_irq_restore(l);
    > return ...;
    > + }
    > |
    > spin_unlock_irqrestore(E2,l);
    > |
    > local_irq_restore(l);
    > )
    > //

    >
    > Signed-off-by: Julia Lawall
    >
    > ---
    > arch/ia64/kvm/kvm-ia64.c | 9 +++++++--
    > 1 files changed, 7 insertions(+), 2 deletions(-)
    >
    > diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
    > index 318b811..14e5c99 100644
    > --- a/arch/ia64/kvm/kvm-ia64.c
    > +++ b/arch/ia64/kvm/kvm-ia64.c
    > @@ -125,8 +125,10 @@ void kvm_arch_hardware_enable(void *garbage)
    > PAGE_KERNEL));
    > local_irq_save(saved_psr);
    > slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
    > - if (slot < 0)
    > + if (slot < 0) {
    > + local_irq_restore(saved_psr);
    > return;
    > + }
    > local_irq_restore(saved_psr);


    If this change makes sense, how about merging the two local_irq_restore
    calls and put them before the if? And shouldn't your checker be able to
    figure this?

    >
    > spin_lock(&vp_lock);
    > @@ -160,8 +162,10 @@ void kvm_arch_hardware_disable(void *garbage)
    >
    > local_irq_save(saved_psr);
    > slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
    > - if (slot < 0)
    > + if (slot < 0) {
    > + local_irq_restore(saved_psr);
    > return;
    > + }
    > local_irq_restore(saved_psr);
    >

    Same as above.

    > status = ia64_pal_vp_exit_env(host_iva);
    > @@ -1258,6 +1262,7 @@ static int vti_vcpu_setup(struct kvm_vcpu *vcpu, int id)
    > uninit:
    > kvm_vcpu_uninit(vcpu);
    > fail:
    > + local_irq_restore(psr);
    > return r;
    > }
    >
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html
    > Please read the FAQ at http://www.tux.org/lkml/


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  3. Re: [PATCH 1/2] arch/ia64/kvm/kvm-ia64.c: Add local_irq_restore in error handling code

    On Tue, 22 Jul 2008, Simon Holm Thøgersen wrote:

    > tir, 22 07 2008 kl. 18:44 +0200, skrev Julia Lawall:
    > > From: Julia Lawall
    > >
    > > There is a call to local_irq_restore in the normal exit case, so it would
    > > seem that there should be one on an error return as well.
    > >
    > > The semantic patch that makes this change is as follows:
    > > (http://www.emn.fr/x-info/coccinelle/)
    > >
    > > //
    > > @@
    > > expression l;
    > > expression E,E1,E2;
    > > @@
    > >
    > > local_irq_save(l);
    > > ... when != local_irq_restore(l)
    > > when != spin_unlock_irqrestore(E,l)
    > > when any
    > > when strict
    > > (
    > > if (...) { ... when != local_irq_restore(l)
    > > when != spin_unlock_irqrestore(E1,l)
    > > + local_irq_restore(l);
    > > return ...;
    > > }
    > > |
    > > if (...)
    > > + {local_irq_restore(l);
    > > return ...;
    > > + }
    > > |
    > > spin_unlock_irqrestore(E2,l);
    > > |
    > > local_irq_restore(l);
    > > )
    > > //

    > >
    > > Signed-off-by: Julia Lawall
    > >
    > > ---
    > > arch/ia64/kvm/kvm-ia64.c | 9 +++++++--
    > > 1 files changed, 7 insertions(+), 2 deletions(-)
    > >
    > > diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
    > > index 318b811..14e5c99 100644
    > > --- a/arch/ia64/kvm/kvm-ia64.c
    > > +++ b/arch/ia64/kvm/kvm-ia64.c
    > > @@ -125,8 +125,10 @@ void kvm_arch_hardware_enable(void *garbage)
    > > PAGE_KERNEL));
    > > local_irq_save(saved_psr);
    > > slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
    > > - if (slot < 0)
    > > + if (slot < 0) {
    > > + local_irq_restore(saved_psr);
    > > return;
    > > + }
    > > local_irq_restore(saved_psr);

    >
    > If this change makes sense, how about merging the two local_irq_restore
    > calls and put them before the if? And shouldn't your checker be able to
    > figure this?


    No, it pretty much only does what it's told, which is to put a
    local_irq_restore before the return.

    Since slot is a local variable, it does seem like the call to
    local_irq_restore could be safely moved upwards, so I will do that
    instead.

    thanks,
    julia


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