virhostdev: remove virHostdevReattachPCIDevice
virHostdevReattachPCIDevice() is a static that simply does a wait loop with virPCIDeviceWaitForCleanup() before calling virPCIDeviceReattach(). This loop traces back to commit d1e5676c, aiming to solve a race condition between Libvirt returning the device back to the host and QEMU trying to access it in the meantime, which resulted in QEMU exiting on error and killing the guest. This happens because device_del is asynchronous, returning OK even if the guest didn't release the device. Commit 01abc8a1 moved this code to qemu_hostdev.c, 82e8dd4c added the pci-stub conditional for the loop, 899b2611 moved the code to virhostdev.c where it stood until now. The intent of this wait loop is still valid: device_del is still not bullet proof into preventing the conditions that commit d1e5676c aimed to fix, especially when considering all the architectures we must support. However, this loop is executed only in virHostdevReattachPCIDevice(), leaving every other virPCIDeviceReattach() call prone to that error. Let's move the wait loop code to virPCIDeviceReattach(). This will: - make every reattach call safe from this race condition with the pci-stub; - allow for a bit of code cleanup (virHostdevReattachPCIDevice() can be erased, and virHostdevReAttachPCIDevices() can use virPCIDeviceReattach() directly); - make it easier to understand the overall reattach mechanisms in Libvirt, without the risk of a newcomer wondering why reattach is done slightly different in some instances. Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com> Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Showing
想要评论请 注册 或 登录