network: fix possible deadlock in DefaultDiscovery #741
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golangcibot
reviewed
Mar 10, 2020
Why a deadlock can occur:
1. (*DefaultDiscovery).run() has a for loop over requestCh channel.
2. (*DefaultDiscovery).RequestRemote() send to this channel while
holding a mutex.
3. (*DefaultDiscovery).RegisterBadAddr() tries to take mutex for write.
4. Second select-case can't take mutex for read because of (3).
Codecov Report
@@ Coverage Diff @@
## master #741 +/- ##
=======================================
Coverage 66.68% 66.68%
=======================================
Files 136 136
Lines 12269 12269
=======================================
Hits 8181 8181
Misses 3692 3692
Partials 396 396
Continue to review full report at Codecov.
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roman-khimov
approved these changes
Mar 10, 2020
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Why a deadlock can occur:
(*DefaultDiscovery).run()has a for loop overrequestChchannel.(*DefaultDiscovery).RequestRemote()send to this channel while holding a mutex.(*DefaultDiscovery).RegisterBadAddr()tries to take mutex for write.