[Xen-devel] RCU locks in Xen!

["Jayaraman, Bhaskar" <Bhaskar.Jayaraman@xxxxxxx>]

I see that rcu locks in Xen code are empty or in other words do nothing, and even rcu_dereference also doesn’t assign pointers through a temporary variable. So is it possible that while domain destruction, while I’m traversing through the domain_hash, list as in rcu_lock_domain_by_id(), I could end up with an invalid pointer?

This is because I see that domain_destroy simply calls complete_domain_destroy which frees up the domain pointer and it seems like it could be possible that while traversing through the hash list in rcu_lock_domain_by_id I could end up with a domain pointer which domain_destroy might have just destroyed and I can’t proceed further down the list.

 

Please let me know if there’s something else that I’m overlooking and if not then how come we don’t see domains/Xen crashing because of this caveat.

 

Regards,

Bhaskar.

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