lib/model: Acquire fmut lock in ensureIndexHandler (fixes #9234) #9235
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Towards the end of the function f.folderCfgs and f.folderRunners are read without the lock.
| @@ -1346,6 +1346,9 @@ func (m *model) ensureIndexHandler(conn protocol.Connection) *indexHandlerRegist | |||
| deviceID := conn.DeviceID() | |||
| connID := conn.ConnectionID() | |||
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| // We must acquire fmut first when acquiring both locks. | |||
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Yes but does RLock count as acquiring? Gut feeling says no...?
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I don't see why not? A read-lock can still produce a deadlock when race with a fmut-pmut (full) lock in another function, if the first (full lock) is acquired in both functions and then the subsequent locks (whether read or full) are blocking.
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Yeah, I wasn't thinking "does the order matter" but rather "is an RLock enough to prevent deadlocks", but I see we already do precisely this thing in at least one other place and I can't think of an ordering that would cause a deadlock.
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Oh now I get - I indeed haven't thought about that just assumed it's ok. And I too can't think of how only acquiring a read-lock would cause a deadlock (not that this is a very strong indicator that there is none ':) ).
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Towards the end of the function f.folderCfgs and f.folderRunners are read without the lock.