Hi,
We believe there might be a bug in the i40evf driver.
We think that there is race issue between i40evf_reset_task and i40evf_down /
i40evf_open.
The reason is that the functions napi_enable / napi_disable must be called in
pairs
in order not to loop indefinitely (or crash).
Consider the following:
ifconfig eth1 mtu 1000 & ifconfig eth1 up
What happens now is that the change of mtu schedules a reset. Suppose the reset
task starts,
and the first call to netif_running (after continue_reset) returns false.
Before the thread reaches
the second call to netif_running, i40evf_open starts in another thread. Then
the second netif_running
in reset will return true, and we will have 2 consecutive calls of napi_enable.
We could not reproduce this particular situation in practice (probably due to
the short timing).
However, we did hang the driver using a call to ndo_close() followed quickly by
"ethtool -G eth1 rx 4096". In this case netif_running will return true always
(as we bypassed
the call to dev_close), the reset will be scheduled before the interface
finishes going down,
and 2 calls to napi_disable will happen.
Please let us know your opinion.
Best wishes,
Tudor, Codrut
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