Re: [Xen-devel] [PATCH 2/2] x86/IRQ: consolidate IRQ disabling when acquiring vector lock

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/11/11 14:27, Jan Beulich wrote:
> x86/IRQ: consolidate IRQ disabling when acquiring vector lock
>
> __assign_irq_vector() doesn't need to disable interrupts (its callers
> are required to when acquiring the lock), and set_desc_affinity() can
> use the normal spin lock primitives.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

> --- a/xen/arch/x86/irq.c
> +++ b/xen/arch/x86/irq.c
> @@ -429,7 +429,6 @@ static int __assign_irq_vector(
>      static int current_vector = FIRST_DYNAMIC_VECTOR, current_offset = 0;
>      unsigned int old_vector;
>      int cpu, err;
> -    unsigned long flags;
>      cpumask_t tmp_mask;
>      vmask_t *irq_used_vectors = NULL;
>  
> @@ -493,7 +492,6 @@ next:
>          /* Found one! */
>          current_vector = vector;
>          current_offset = offset;
> -        local_irq_save(flags);
>          if (old_vector) {
>              desc->arch.move_in_progress = 1;
>              cpumask_copy(desc->arch.old_cpu_mask, desc->arch.cpu_mask);
> @@ -521,7 +519,6 @@ next:
>          }
>  
>          err = 0;
> -        local_irq_restore(flags);
>          break;
>      }
>      return err;
> @@ -720,11 +717,9 @@ unsigned int set_desc_affinity(struct ir
>  
>      irq = desc->irq;
>  
> -    local_irq_save(flags);
> -    lock_vector_lock();
> +    spin_lock_irqsave(&vector_lock, flags);
>      ret = __assign_irq_vector(irq, desc, mask);
> -    unlock_vector_lock();
> -    local_irq_restore(flags);
> +    spin_unlock_irqrestore(&vector_lock, flags);
>  
>      if (ret < 0)
>          return BAD_APICID;
>
>
>

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com


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