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SubjectRe: [EXTERNAL] [PATCH 1/2] PCI: hv: Use IDR to generate transaction IDs for VMBus hardening
> > @@ -1208,6 +1211,27 @@ static void hv_pci_read_config_compl(void
> > *context, struct pci_response *resp,
> > complete(&comp->comp_pkt.host_event);
> > }
> >
> > +static inline int alloc_request_id(struct hv_pcibus_device *hbus,
> > + void *ptr, gfp_t gfp)
> > +{
> > + unsigned long flags;
> > + int req_id;
> > +
> > + spin_lock_irqsave(&hbus->idr_lock, flags);
> > + req_id = idr_alloc(&hbus->idr, ptr, 1, 0, gfp);
>
> [Saurabh Singh Sengar] Many a place we are using alloc_request_id with GFP_KERNEL, which results this allocation inside of spin lock with GFP_KERNEL.

That's a bug.


> Is this a good opportunity to use idr_preload ?

I'd rather fix (and 'simplify' a bit the interface) by doing:

static inline int alloc_request_id(struct hv_pcibus_device *hbus, void *ptr)
{
unsigned long flags;
int req_id;

spin_lock_irqsave(&hbus->idr_lock, flags);
req_id = idr_alloc(&hbus->idr, ptr, 1, 0, GFP_ATOMIC);
spin_unlock_irqrestore(&hbus->idr_lock, flags);
return req_id;
}

Thoughts?

Thanks,
Andrea

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