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daemon: Fix the "close of closed channel" panic #11056

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merged 1 commit into from Apr 23, 2020
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daemon: Fix the "close of closed channel" panic #11056

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7 changes: 5 additions & 2 deletions pkg/ipam/crd.go
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Expand Up @@ -77,7 +77,8 @@ type nodeStore struct {
allocationPoolSize map[Family]int

// signal for completion of restoration
restoreFinished chan bool
restoreFinished chan bool
restoreCloseOnce sync.Once

conf Configuration
}
Expand Down Expand Up @@ -623,5 +624,7 @@ func (a *crdAllocator) Dump() (map[string]string, string) {

// RestoreFinished marks the status of restoration as done
func (a *crdAllocator) RestoreFinished() {
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The aim here is to restore all endpoints before triggering sync with upstream, so I think we should close a.store.restoreFinished only after the restoration of both IPv6Allocator and IPv4Allocator are finished. They are called from here:

cilium/daemon/cmd/daemon.go

Lines 491 to 498 in 90b256e

if option.Config.IPAM == option.IPAMCRD || option.Config.IPAM == option.IPAMENI || option.Config.IPAM == option.IPAMAzure {
if option.Config.EnableIPv6 {
d.ipam.IPv6Allocator.RestoreFinished()
}
if option.Config.EnableIPv4 {
d.ipam.IPv4Allocator.RestoreFinished()
}
}

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@jaffcheng @Sen666666 Looking at the code, this comment seems to be a potential further fix that should go in at some point, but does not directly interact with this specific PR #11056 that just fixes a specific crash issue. I'd like to merge this PR as-is to fix the crash, then you can follow up to address these comments. Does that sound reasonable?

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Yes, let's address this comment in a follow-up PR.

close(a.store.restoreFinished)
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please use a Once.Do here, it will guarantee that this call is only executed once. (The Once will be a field of nodeStore.

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thanks for the suggestion, I will try to do some modification.

a.store.restoreCloseOnce.Do(func() {
close(a.store.restoreFinished)
})
}