Xen devel - Jan 2010 - [PATCH] x86: check if desc->action is NULL when unbinding guest pirq

Before igb PF driver is unloaded, dom0 doesn''t unload igbvf driver
automatically. When igb drver is unloaded, it invokes the
PHYSDEVOP_manage_pci_remove hypercall to remove the VFs and xen frees the msi
irqs by pci_cleanup_msi() -> ... -> dynamic_irq_cleanup() and sets the
desc->action to NULL.
igbvf driver knows the VF is disappearing via a hook ndo_stop() in dev_close()
and tries to unbind the pirq and xen would crash as the desc->action
is NULL now.
The patch adds the checking for this.

Thanks,
-- Dexuan
 


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On 22/01/2010 08:01, "Cui, Dexuan" <dexuan.cui@intel.com> wrote:
> Before igb PF driver is unloaded, dom0 doesn''t unload igbvf driver
> automatically. When igb drver is unloaded, it invokes the
> PHYSDEVOP_manage_pci_remove hypercall to remove the VFs and xen frees the
msi
> irqs by pci_cleanup_msi() -> ... -> dynamic_irq_cleanup() and sets
the
> desc->action to NULL.
> igbvf driver knows the VF is disappearing via a hook ndo_stop() in
dev_close()
> and tries to unbind the pirq and xen would crash as the desc->action
> is NULL now.
> The patch adds the checking for this.
Although I checked this in as c/s 20844, I now wonder what the
''desc->status|IRQ_DISABLED'' is included for? (e.g., see
below extract:)

+ if (unlikely((desc->status | IRQ_DISABLED) && (desc->action ==
NULL)))

Looks pointless: should this just be
''if(desc->action==NULL)''?

 -- Keir



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Keir Fraser wrote:
> On 22/01/2010 08:01, "Cui, Dexuan" <dexuan.cui@intel.com>
wrote:
> 
>> Before igb PF driver is unloaded, dom0 doesn''t unload igbvf
driver
>> automatically. When igb drver is unloaded, it invokes the
>> PHYSDEVOP_manage_pci_remove hypercall to remove the VFs and xen
>> frees the msi irqs by pci_cleanup_msi() -> ... ->
>> dynamic_irq_cleanup() and sets the desc->action to NULL. igbvf
>> driver knows the VF is disappearing via a hook ndo_stop() in
>> dev_close() and tries to unbind the pirq and xen would crash as the
>> desc->action  
>> is NULL now.
>> The patch adds the checking for this.
> 
> Although I checked this in as c/s 20844, I now wonder what the
> ''desc->status|IRQ_DISABLED'' is included for? (e.g.,
see below
> extract:) 
> 
> + if (unlikely((desc->status | IRQ_DISABLED) && (desc->action
=> NULL)))
> 
> Looks pointless: should this just be
''if(desc->action==NULL)''?
(Sorry for the late reply as I was out for several days.)
Yes, I think so. Please improve it. :-)

Thanks,
-- Dexuan
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