On Tue, 6 Dec 2016 00:37:08 +0000 Long Li <[email protected]> wrote:
> > -----Original Message----- > > From: Stephen Hemminger [mailto:[email protected]] > > Sent: Monday, December 5, 2016 8:53 AM > > To: Long Li <[email protected]> > > Cc: KY Srinivasan <[email protected]>; Haiyang Zhang > > <[email protected]>; Bjorn Helgaas <[email protected]>; > > [email protected]; [email protected]; linux- > > [email protected] > > Subject: Re: [PATCH] pci-hyperv: use kmalloc to allocate hypercall params > > buffer > > > > On Tue, 8 Nov 2016 14:04:38 -0800 > > Long Li <[email protected]> wrote: > > > > > + spin_lock_irqsave(&hbus->retarget_msi_interrupt_lock, flags); > > > + > > > + params = &hbus->retarget_msi_interrupt_params; > > > + memset(params, 0, sizeof(*params)); > > > + params->partition_id = HV_PARTITION_ID_SELF; > > > + params->source = 1; /* MSI(-X) */ > > > + params->address = msi_desc->msg.address_lo; > > > + params->data = msi_desc->msg.data; > > > + params->device_id = (hbus->hdev->dev_instance.b[5] << 24) | > > > (hbus->hdev->dev_instance.b[4] << 16) | > > > (hbus->hdev->dev_instance.b[7] << 8) | > > > (hbus->hdev->dev_instance.b[6] & 0xf8) | > > > PCI_FUNC(pdev->devfn); > > > - params.vector = cfg->vector; > > > + params->vector = cfg->vector; > > > > > > for_each_cpu_and(cpu, dest, cpu_online_mask) > > > - params.vp_mask |= (1ULL << > > vmbus_cpu_number_to_vp_number(cpu)); > > > + params->vp_mask |= (1ULL << > > vmbus_cpu_number_to_vp_number(cpu)); > > > + > > > + hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, params, NULL); > > > > > > - hv_do_hypercall(HVCALL_RETARGET_INTERRUPT, ¶ms, NULL); > > > + spin_unlock_irqrestore(&hbus->retarget_msi_interrupt_lock, flags); > > > > It looks like the additional locking here is being overly paranoid. > > The caller is already holding the irq descriptor lock. Look at fixup_irqs. > > You are right. On my test machine, there are two possible places calling > hv_irq_unmask(): request _irq() and handle_edge_irq(). They both have > desc->lock held when calling .irq_unmask on the chip. A review of the IRQ > code shows that desc->lock is always held while calling chip->irq_unmask(). > > Since the lock doesn't do any harm and it is not on performance code path, we > can remove the lock in the upcoming patches. Why add it then remove it, your patch hasn't been accepted. Please revise it and remove it. Don't add additional unnecessary code.
