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if: Fix panic when destroying vnet and epair simultaneously

Authored by kp on Nov 26 2020, 12:04 AM.



When destroying a vnet and an epair (with one end in the vnet) we often
panicked. This was the result of the destruction of the epair, which
destroys both ends, happening while vnet_if_return() was moving the
struct ifnet to its home vnet. This can result in a freed ifnet being
re-added to the home vnet V_ifnet list. That in turn panics the next
time the ifnet is used.

Prevent this race by ensuring that vnet_if_return() cannot run at the
same time as if_detach() or epair_clone_destroy().

PR: 238870, 234985, 244703, 250870
MFC after: 2 weeks
Sponsored by: Modirum MDPay

Diff Detail

rS FreeBSD src repository - subversion
Automatic diff as part of commit; lint not applicable.
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

kp requested review of this revision.Nov 26 2020, 12:04 AM
This revision was not accepted when it landed; it landed in state Needs Review.Dec 1 2020, 4:24 PM
This revision was automatically updated to reflect the committed changes.