Commits on May 5, 2021

1. wireguard: Fix timeout in unit test …

   This commit fixes a deadlock in a unit test which ironically tests for
   deadlocks. The unit test in question ensures that the `wireguard.Agent`
   `UpdatePeer` method does not create a deadlock if a concurrent IPCache
   update is performed.
   
   The previous version of this test wanted to ensure this by taking a
   read-lock on the IPCache, which would ensure that only `UpdatePeer`
   would make progress (as it also just takes an RLock). However, that
   approach could lead to a timeout when `ipCache.Upsert` was invoked
   before `wgAgent.UpdatePeer`, as due to the FIFO nature of underlying
   mutex implementation, `UpdatePeer` will never obtain an `RLock` if there
   is a waiting writer.
   
   This commit addresses this by taking the `wgAgent` lock instead. This
   means that `UpdatePeer` will lock the IPCache and then wait for the
   `wgAgent` lock to become available. Any concurrent IPCache updates will
   also be blocked until `UpdatePeer` has finished as before.
   
   This commit also introduces some additional checks to ensure the spawned
   go routines have actually been scheduled. This is still best effort, as
   there is easy way to ensure that a certain method is blocked on a
   particular mutex.
   
   Signed-off-by: Sebastian Wicki <sebastian@isovalent.com>

   

   gandro committed May 5, 2021
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