Re: [Xen-devel] [PATCH 06/10] xen: arm: Use SMP barriers when that is all which is required.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 28 Jun 2013, Ian Campbell wrote:
> As explained in the previous commit SMP barriers can be used when all we care
> about is synchronising against other processors.
> 
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> ---
>  xen/arch/arm/mm.c      |    2 +-
>  xen/arch/arm/smpboot.c |    4 ++--
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index c5213f2..3f049cb 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -776,7 +776,7 @@ void share_xen_page_with_guest(struct page_info *page,
>      page->u.inuse.type_info |= PGT_validated | 1;
>  
>      page_set_owner(page, d);
> -    wmb(); /* install valid domain ptr before updating refcnt. */
> +    smp_wmb(); /* install valid domain ptr before updating refcnt. */
>      ASSERT((page->count_info & ~PGC_xen_heap) == 0);
>  
>      /* Only add to the allocation list if the domain isn't dying. */
> diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
> index 8011987..727e09f 100644
> --- a/xen/arch/arm/smpboot.c
> +++ b/xen/arch/arm/smpboot.c
> @@ -170,11 +170,11 @@ void __cpuinit start_secondary(unsigned long 
> boot_phys_offset,
>  
>      /* Run local notifiers */
>      notify_cpu_starting(cpuid);
> -    wmb();
> +    smp_wmb();
>  
>      /* Now report this CPU is up */
>      cpumask_set_cpu(cpuid, &cpu_online_map);
> -    wmb();
> +    smp_wmb();
>  
>      local_irq_enable();

Did you missed few mb() in smpboot.c?

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