Hello,
On 29/11/17 06:15, Yisheng Xie wrote:
> Hi Jean,
>
> On 2017/10/6 21:31, Jean-Philippe Brucker wrote:
>> - if (domain->ext_handler) {
>> + if (domain->handler_flags & IOMMU_FAULT_HANDLER_ATOMIC) {
>> + fault->flags |= IOMMU_FAULT_ATOMIC;
>
> Why remove the condition of domain->ext_handler? should it be much better
> like:
> if ((domain->handler_flags & IOMMU_FAULT_HANDLER_ATOMIC) &&
> domain->ext_handler)
>
> If domain->ext_handler is NULL, and (domain->handler_flags &
> IOMMU_FAULT_HANDLER_ATOMIC)
> is true. It will oops, right?
I removed the check because ext_handler shouldn't be NULL if handler_flags
has a bit set (as per iommu_set_ext_fault_handler). But you're right that
this is fragile, and I overlooked the case where users could call
set_ext_fault_handler to clear the fault handler.
(Note that this ext_handler will most likely be replaced by the fault
infrastructure that Jacob is working on:
https://patchwork.kernel.org/patch/10063385/ to which we should add the
atomic/blocking flags)
Thanks,
Jean
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