On Thu, 2020-04-30 at 18:37 +0530, Madhuparna Bhowmik wrote: > On Wed, Apr 29, 2020 at 03:40:58PM -0700, Paul E. McKenney wrote: > > You do of course need the code to use the RCU variants of list_add*(). > > And also list_for_each_entry_rcu(), as in the current code. > > > > There are several options, none of them perfect: > > > > 1. Add (not otherwise needed) calls to rcu_read_lock() and > > rcu_read_unlock() and leave list_for_each_entry_rcu() unchanged. > > > > 2. Add "true" for the optional fourth argument to > > list_for_each_entry_rcu(). This will suppress the complaints, > > but would (incorrectly) continue to do so should this code change > > so as to be able to delete form this list. > > > > 3. Switch from list_for_each_entry_rcu() to its lockless counterpart, > > list_for_each_entry_lockless(). This is simiar to #2 above, but > > at least the name lets people know that something unusual is up. > > > > If it was my code, I would take door #3. ;-) > > > Thanks a lot for your inputs on this. I will send a patch soon. Please remember to expand the "mutex" comment in evm_write_xattrs() to reflect the reason why using list_for_each_entry_lockless() is safe. thanks, Mimi
