On Mon, Sep 27, 2021 at 12:01:19PM -0300, Jason Gunthorpe wrote: > On Mon, Sep 27, 2021 at 01:46:31PM +0000, Shameerali Kolothum Thodi wrote: > > > > > > Nope, this is locked wrong and has no lifetime management. > > > > > > > > Ok. Holding the device_lock() sufficient here? > > > > > > You can't hold a hisi_qm pointer with some kind of lifecycle > > > management of that pointer. device_lock/etc is necessary to call > > > pci_get_drvdata() > > > > Since this migration driver only supports VF devices and the PF > > driver will not be removed until all the VF devices gets removed, > > is the locking necessary here? > > Oh.. That is really busted up. pci_sriov_disable() is called under the > device_lock(pf) and obtains the device_lock(vf). Yes, indirectly, but yes. > > This means a VF driver can never use the device_lock(pf), otherwise it > can deadlock itself if PF removal triggers VF removal. VF can use pci_dev_trylock() on PF to prevent PF removal. > > But you can't access these members without using the device_lock(), as > there really are no safety guarentees.. > > The mlx5 patches have this same sketchy problem. > > We may need a new special function 'pci_get_sriov_pf_devdata()' that > confirms the vf/pf relationship and explicitly interlocks with the > pci_sriov_enable/disable instead of using device_lock() > > Leon, what do you think? I see pci_dev_lock() and similar functions, they are easier to understand that specific pci_get_sriov_pf_devdata(). Thanks > > Jason
