i40e v2.28.5+: VF initialization fails on PREEMPT kernels with multiple VFs

[usr06c4]

in commit fd19db9, the change ignores i40e_sync_vf_state()'s return value and re-reads
VF state, allowing concurrent operations to cause spurious -EINVAL failures during legitimate VF initialization.
original code semantics before this change were correct (wait until flag or timeout)

Manifests on CONFIG_PREEMPT kernels with multiple simultaneous VFs due to larger preemption window.
causes iavf to get stuck in an infinite retry loop
Dec 05 18:51:20 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config (-5)
Dec 05 18:51:20 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Failed to communicate with PF; waiting before retry
Dec 05 18:51:25 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Hardware came out of reset. Attempting reinit.
Dec 05 18:51:25 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config due to PF error condition, not retrying
Dec 05 18:51:25 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config (-5)
Dec 05 18:51:25 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Failed to communicate with PF; waiting before retry
Dec 05 18:51:31 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Hardware came out of reset. Attempting reinit.
Dec 05 18:51:31 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config due to PF error condition, not retrying
Dec 05 18:51:31 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config (-5)
Dec 05 18:51:31 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Failed to communicate with PF; waiting before retry
Dec 05 18:51:36 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Hardware came out of reset. Attempting reinit.
Dec 05 18:51:36 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config due to PF error condition, not retrying
Dec 05 18:51:36 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config (-5)
Dec 05 18:51:36 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Failed to communicate with PF; waiting before retry
Dec 05 18:51:41 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Hardware came out of reset. Attempting reinit.
Dec 05 18:51:41 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config due to PF error condition, not retrying
Dec 05 18:51:41 xxxxxxxxxxx kernel: iavf 0000:21:0a.0: Unable to get VF config (-5)

-       if (!i40e_sync_vf_state(vf, I40E_VF_STATE_INIT)) {
+       /* sync once, test multiple states later */
+       i40e_sync_vf_state(vf, I40E_VF_STATE_INIT);
+
+       if (!test_bit(I40E_VF_STATE_INIT, &vf->vf_states) ||
+           test_bit(I40E_VF_STATE_RESOURCES_LOADED, &vf->vf_states)) {
                aq_ret = I40E_ERR_PARAM;
                goto err;

last working released intel version is i40e-2.27.8.
thank you