http://llvm.org/bugs/show_bug.cgi?id=8441
Summary: Race condition in AttributesList
Product: new-bugs
Version: 2.8
Platform: PC
OS/Version: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
AssignedTo: [email protected]
ReportedBy: [email protected]
CC: [email protected]
This bug seems to be a race condition relating to the static AttributesList in
Attributes.cpp. Access to the AttributesList is locked, but my theory for what
was going on is that at line 125-126, when dropping a reference, we decrement
the count, then check to see if it's zero, then delete "this" (if the refcount
was zero). After we've checked that the count is zero, but before deleting
"this", "this" is still in the AttributesLists set. So in the mean time,
another thread comes along, finds "this" in AttributesList, and references it.
But the first thread has already determined that the count *was* 0, and then
comes back and deletes "this", even though it's now in use by the second
thread.
I've attached a patch which seems to fix this problem for me -- not intended as
a final solution, but it is useful for illustrating the problem.
I'll attach a program which reproduces the problem once I figure out how to
have multiple attachements.
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