[llvm-dev] A potential race on StaticList in RegisterManagedStatic

[Mehdi Amini via llvm-dev]

What about the lock that is taken?

MutexGuard Lock(*getManagedStaticMutex());


— 
Mehdi


> On Dec 25, 2016, at 11:14 PM, Viacheslav Nikolaev via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Though it won't actually help to guard this: while (StaticList) - a fence here is needed...
> 
> On Mon, Dec 26, 2016 at 9:20 AM, Viacheslav Nikolaev <viacheslav.nikolaev at gmail.com <mailto:viacheslav.nikolaev at gmail.com>> wrote:
> Ptr member of ManagedStaticBase is now atomic.
> In ManagedStaticBase::RegisterManagedStatic we have such code:
> 
>       void *Tmp = Creator();
> 
>       Ptr.store(Tmp, std::memory_order_release);
>       DeleterFn = Deleter;
>       
>       // Add to list of managed statics.
>       Next = StaticList;
>       StaticList = this;
> 
> 
> StaticList is not atomic and not guarded by any fence.
> The same applies to the members DeleterFn and Next.
> 
> Doesn't it seem reasonable to change the code to
> 
>       DeleterFn = Deleter;
>       
>       // Add to list of managed statics.
>       Next = StaticList;
>       StaticList = this;
>       Ptr.store(Tmp, std::memory_order_release);
> 
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