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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] xen/arm: make accesses to desc->status flags atomic
On Fri, 2014-06-13 at 12:24 +0100, Stefano Stabellini wrote:
> Using *_bit manipulation functions on desc->status is safe on arm64:
> status is an unsigned int but is the first field of a struct that
> contains pointers, therefore the alignement of the struct is at least 8
"alignment"
> bytes.
Are the non underscore versions of the register definitions even used
after this? If not then I'd prefer to just use the non-underscored
names.
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> xen/arch/arm/gic.c | 10 +++++-----
> xen/arch/arm/irq.c | 29 +++++++++++++++--------------
> 2 files changed, 20 insertions(+), 19 deletions(-)
>
> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> index a4422fd..2a88998 100644
> --- a/xen/arch/arm/gic.c
> +++ b/xen/arch/arm/gic.c
> @@ -137,7 +137,7 @@ static void gic_irq_enable(struct irq_desc *desc)
> ASSERT(spin_is_locked(&desc->lock));
>
> spin_lock_irqsave(&gic.lock, flags);
> - desc->status &= ~IRQ_DISABLED;
> + clear_bit(_IRQ_DISABLED, &desc->status);
> dsb(sy);
> /* Enable routing */
> GICD[GICD_ISENABLER + irq / 32] = (1u << (irq % 32));
> @@ -154,7 +154,7 @@ static void gic_irq_disable(struct irq_desc *desc)
> spin_lock_irqsave(&gic.lock, flags);
> /* Disable routing */
> GICD[GICD_ICENABLER + irq / 32] = (1u << (irq % 32));
> - desc->status |= IRQ_DISABLED;
> + set_bit(_IRQ_DISABLED, &desc->status);
> spin_unlock_irqrestore(&gic.lock, flags);
> }
>
> @@ -277,7 +277,7 @@ void gic_route_irq_to_xen(struct irq_desc *desc, bool_t
> level,
> {
> ASSERT(priority <= 0xff); /* Only 8 bits of priority */
> ASSERT(desc->irq < gic.lines);/* Can't route interrupts that don't exist
> */
> - ASSERT(desc->status & IRQ_DISABLED);
> + ASSERT(test_bit(_IRQ_DISABLED, &desc->status));
> ASSERT(spin_is_locked(&desc->lock));
>
> desc->handler = &gic_host_irq_type;
> @@ -296,7 +296,7 @@ void gic_route_irq_to_guest(struct domain *d, struct
> irq_desc *desc,
> ASSERT(spin_is_locked(&desc->lock));
>
> desc->handler = &gic_guest_irq_type;
> - desc->status |= IRQ_GUEST;
> + set_bit(_IRQ_GUEST, &desc->status);
>
> gic_set_irq_properties(desc->irq, level, cpumask_of(smp_processor_id()),
> GIC_PRI_IRQ);
> @@ -685,7 +685,7 @@ static void gic_update_one_lr(struct vcpu *v, int i)
> clear_bit(i, &this_cpu(lr_mask));
>
> if ( p->desc != NULL )
> - p->desc->status &= ~IRQ_INPROGRESS;
> + clear_bit(_IRQ_INPROGRESS, &p->desc->status);
> clear_bit(GIC_IRQ_GUEST_VISIBLE, &p->status);
> clear_bit(GIC_IRQ_GUEST_ACTIVE, &p->status);
> p->lr = GIC_INVALID_LR;
> diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
> index 756250c..d0c7962 100644
> --- a/xen/arch/arm/irq.c
> +++ b/xen/arch/arm/irq.c
> @@ -102,7 +102,7 @@ static inline struct domain *irq_get_domain(struct
> irq_desc *desc)
> {
> ASSERT(spin_is_locked(&desc->lock));
>
> - if ( !(desc->status & IRQ_GUEST) )
> + if ( !test_bit(_IRQ_GUEST, &desc->status) )
> return dom_xen;
>
> ASSERT(desc->action != NULL);
> @@ -166,40 +166,41 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int
> irq, int is_fiq)
> goto out;
> }
>
> - if ( desc->status & IRQ_GUEST )
> + if ( test_bit(_IRQ_GUEST, &desc->status) )
> {
> struct domain *d = irq_get_domain(desc);
>
> desc->handler->end(desc);
>
> - desc->status |= IRQ_INPROGRESS;
> + set_bit(_IRQ_INPROGRESS, &desc->status);
> desc->arch.eoi_cpu = smp_processor_id();
>
> vgic_vcpu_inject_spi(d, irq);
> goto out_no_end;
> }
>
> - desc->status |= IRQ_PENDING;
> + set_bit(_IRQ_PENDING, &desc->status);
>
> /*
> * Since we set PENDING, if another processor is handling a different
> * instance of this same irq, the other processor will take care of it.
> */
> - if ( desc->status & (IRQ_DISABLED | IRQ_INPROGRESS) )
> + if ( test_bit(_IRQ_DISABLED, &desc->status) ||
> + test_bit(_IRQ_INPROGRESS, &desc->status) )
> goto out;
>
> - desc->status |= IRQ_INPROGRESS;
> + set_bit(_IRQ_INPROGRESS, &desc->status);
>
> action = desc->action;
> - while ( desc->status & IRQ_PENDING )
> + while ( test_bit(_IRQ_PENDING, &desc->status) )
> {
> - desc->status &= ~IRQ_PENDING;
> + clear_bit(_IRQ_PENDING, &desc->status);
> spin_unlock_irq(&desc->lock);
> action->handler(irq, action->dev_id, regs);
> spin_lock_irq(&desc->lock);
> }
>
> - desc->status &= ~IRQ_INPROGRESS;
> + clear_bit(_IRQ_INPROGRESS, &desc->status);
>
> out:
> desc->handler->end(desc);
> @@ -222,12 +223,12 @@ void release_irq(unsigned int irq)
>
> action = desc->action;
> desc->action = NULL;
> - desc->status &= ~IRQ_GUEST;
> + clear_bit(_IRQ_GUEST, &desc->status);
>
> spin_unlock_irqrestore(&desc->lock,flags);
>
> /* Wait to make sure it's not being used on another CPU */
> - do { smp_mb(); } while ( desc->status & IRQ_INPROGRESS );
> + do { smp_mb(); } while ( test_bit(_IRQ_INPROGRESS, &desc->status) );
>
> if ( action && action->free_on_release )
> xfree(action);
> @@ -255,7 +256,7 @@ int setup_dt_irq(const struct dt_irq *irq, struct
> irqaction *new)
>
> spin_lock_irqsave(&desc->lock, flags);
>
> - if ( desc->status & IRQ_GUEST )
> + if ( test_bit(_IRQ_GUEST, &desc->status) )
> {
> struct domain *d = irq_get_domain(desc);
>
> @@ -323,10 +324,10 @@ int route_dt_irq_to_guest(struct domain *d, const
> struct dt_irq *irq,
> {
> struct domain *ad = irq_get_domain(desc);
>
> - if ( (desc->status & IRQ_GUEST) && d == ad )
> + if ( test_bit(_IRQ_GUEST, &desc->status) && d == ad )
> goto out;
>
> - if ( desc->status & IRQ_GUEST )
> + if ( test_bit(_IRQ_GUEST, &desc->status) )
> printk(XENLOG_ERR "ERROR: IRQ %u is already used by domain %u\n",
> irq->irq, ad->domain_id);
> else
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