Re: [Xen-devel] [PATCH 8/8] evtchn: add FIFO-based event channel hypercalls and port ops

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.03.13 at 14:42, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
> On 20/03/13 10:47, Jan Beulich wrote:
>>>>> On 19.03.13 at 22:00, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
>>> +struct evtchn_fifo_queue {
>>> +    volatile uint32_t *head; /* points into control block */
>> 
>> I still think that explicit barriers are the way to go. Unless Linux'es
>> view on this has changed, you'll have issues getting the Linux folks
>> to accept this.
> 
> This volatile can just be removed.  head is only written by Xen in one
> place and it is immediately followed by a spin_unlock() which is a barrier.

A release type barrier only, but that presumably is sufficient for
the purposes here.

Jan


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