[PATCH] irqchip: gic: use dmb ishst instead of dsb when raising a softirq

[Will Deacon]

On Thu, Feb 20, 2014 at 05:42:07PM +0000, Will Deacon wrote:
> When sending an SGI to another CPU, we require a barrier to ensure that
> any pending stores to normal memory are made visible to the recipient
> before the interrupt arrives.
> 
> Rather than use a vanilla dsb() (which will soon cause an assembly error
> on arm64) before the writel_relaxed, we can instead use dsb(ishst),
> since we just need to ensure that any pending normal writes are visible
> within the inner-shareable domain before we poke the GIC.
> 
> With this observation, we can then further weaken the barrier to a
> dmb(ishst), since other CPUs in the inner-shareable domain must observe
> the write to the distributor before the SGI is generated.
> 
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Acked-by: Marc Zyngier <marc.zyngier at arm.com>
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: Will Deacon <will.deacon at arm.com>
> ---
> 
> Hi Olof,
> 
> Please can you take this via arm-soc for 3.15? That will let me activate
> the new barrier options for arm64 at the end of the next merge window
> (in the meantime, you can pass them but they are ignored).

I still can't see this in -next, any chance you could queue it please?

Will