SeokYeon Hwang <syeon.hw...@samsung.com> writes: >> -----Original Message----- >> From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo >> Bonzini >> Sent: Wednesday, November 05, 2014 11:55 PM >> To: Michael S. Tsirkin >> Cc: Markus Armbruster; SeokYeon Hwang; qemu-devel@nongnu.org >> Subject: Re: [Qemu-devel] [PATCH] pci: fixed mismatch of error-handling >> between pci_qdev_init() and qdev >> >> >> >> On 05/11/2014 14:28, Michael S. Tsirkin wrote: >> > > I think bypassing the question by converting to realize makes the >> > > most sense... >> > >> > I'm fine with doing that but Markus's patches wouldn't yet have solved >> > the problem by themselves since init is still around, right? >> > >> > This probably means fixing this bug can't justify merging the realize >> > patchset after freeze. >> >> Yes, I agree. I meant that the API is not very well defined. I would >> handle everything else on a case-by-case basis, by reviewing each init >> function that is converted to realize. >> >> Since the patch was for an out-of-tree device, it can wait for 2.3 anyway. >> >> Paolo > > I cannot fully understand your conversation.
You appear to have a PCIDeviceClass method init() returning a positive value. Doesn't work. Only values <= 0 do. Your proposed fix is to make its caller treat a positive value like a negative one. Paolo points out that init()'s contract is unclear. His preferred way of clarifying it is to convert PCI from init() to realize(), which has a sufficiently clear contract. Doesn't help you now. My "pci: Partial conversion to realize" series, will help you once it lands, but only if you convert your device. You obviously want a solution earlier. The one you proposed implicitly clarifies the PCIDeviceClass init() contract to "zero means success, anything else failure". I don't think that's a good idea, because it makes PCIDeviceClass's init() differ from DeviceClass's. There, non-negative value means success, negative means failure (see device_realize()). Fix your device not to return positive values instead. You could additionally fix pci_qdev_init() to treat positive numbers as success, for consistency with device_realize(), but that requires auditing all existing PCIDeviceClass init() methods. Waste of your time, because they all go away when we convert to realize(). > But, I think this patch is still worth before all 'init()' convert to > 'realize()'. > Moreover, It has no side effect at all. I don't like it, because it makes PCIDeviceClass's init() inconsistent with DeviceClass's.
