No, it is also safe even so .The dynamic vector IRQ_MOVE_CLEANUP_VECTOR is used 
for cleanup vector when IRQ migration and its EOI is never stacked, so only 
NR_DYNAMIC_VECTORS -1 is really used, and the last array cell is always safe to 
store stack pointer. 
Xiantao 
-----Original Message-----
From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx] 
Sent: Tuesday, January 26, 2010 11:02 PM
To: Zhang, Xiantao; xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH] enhancement for unmaskable MSI and two cosmetic fixes.
Is patch #3 even safe? Looks like if a CPU somehow got all dynamic vectors
stacked up, it would overflow into the stackpointer at the end of the array.
 -- Keir
On 26/01/2010 14:35, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> wrote:
> Yeah, at least we have to apply the first two to fix a bug related to
> unmaskable MSI. 
> Xiantao
>
> -----Original Message-----
> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> Sent: Tuesday, January 26, 2010 10:26 PM
> To: Zhang, Xiantao; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] enhancement for unmaskable MSI and two cosmetic fixes.
>
> Are these essential for 4.0.0? I've just tagged -rc2, so they've missed
> that.
>
> -- Keir
>
> On 26/01/2010 14:10, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> wrote:
>
>> 0001: Revert 20334, since it doesn't solve the race for all corner cases.
>> 0002: Fixed unmaskable MSI's IRQ migration.
>> 0003: Reduce eoi stack's size to save per-cpu area.
>> 0004: polarity-switch method for EOI message is only used for
>> non-directed-eoi
>> case. 
>> Xiantao
>
>
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