> -----Original Message----- > From: Stephen Hemminger [mailto:step...@networkplumber.org] > Sent: Monday, December 5, 2016 8:53 AM > To: Long Li <lon...@microsoft.com> > Cc: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang > <haiya...@microsoft.com>; Bjorn Helgaas <bhelg...@google.com>; > de...@linuxdriverproject.org; linux-ker...@vger.kernel.org; linux- > p...@vger.kernel.org > Subject: Re: [PATCH] pci-hyperv: use kmalloc to allocate hypercall params > buffer > > On Tue, 8 Nov 2016 14:04:38 -0800 > Long Li <lon...@exchange.microsoft.com> 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. _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
