Closed Bug 34069 Opened 23 years ago Closed 23 years ago
_Define Property stuck lock bug if JSPROP _[GS]ETTER and property exists in prototype object
Summary says it all. Patch coming up. /be
Status: NEW → ASSIGNED
Target Milestone: --- → M15
Jband, feel free to check in with email@example.com and close this. /be
Brendan, looking at the loop in js_LookupProperty I still have not convinced myself that some object with a long proto chain might not leave the function with extraneous locks on the non-terminal nodes in the chain. But there is lots going on there that I don't quite get. Is there no way that this can happen?
*** Bug 34111 has been marked as a duplicate of this bug. ***
Nominating for beta2. This blocks the usage of the new XUL widgetry and therefore blocks skins.
Jband: rest assured we'd see more stuck locks. The bug in js_DefineProperty was added when I added getters and setters late last year, and it bit hyatt only the other night, when he started defining getters and setters for properties that shadow prototype properties (hyatt, what are some example id's of such props?). The loop in js_LookupProperty has these exits: 1. The false return after newResolve failure, but obj has been unlocked before the call to newResolve (a good idea in general, to avoid deadlocks). 2. Likewise for "old-style" resolve's call in the else clause. 3. The true return when a property has been found, in which case *by definition* the object owning that property should be locked, and it does in fact remain locked; and the property's refcount is incremented. The caller is responsible for calling OBJ_DROP_PROPERTY later, to release the prop and unlock the object in whose scope it lives. 4. The break after finding a null proto link, which terminates the prototype chain -- note again that the current object (whose proto was null) is unlocked just before the if(!proto)break. 5. The immediately following call out to another JSObjectOps (OBJ_LOOKUP_PROPERTY) if the proto-object is not native. Tail recursion after obj has been unlocked just above exit-point 4 (above). The loop then sets obj = proto and iterates. If this isn't a convincing proof I'll burn the weekend constructing a denotational semantic proof! Anyway, to repeat: the bug was in the JS_HAS_GETTER_SETTER-#ifdef'd code in js_DefineProperty, and only there. Is this fix in yet? If so, close the bug or tell me to close it. Thanks, /be
Fix checked in. /be
Status: ASSIGNED → RESOLVED
Closed: 23 years ago
Resolution: --- → FIXED
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