Tejun Heo <t...@kernel.org> wrote: > > The blkg obtained through a blkg_lookup, in a rcu_read section, is > > protected. But, outside that section, a pointer to that blkg is not > > guaranteed to be valid any longer. Stat-update functions seem safe in > > blkg's destruction is rcu delayed. If you have access to a blkg under > rcu, it won't get freed until the rcu read lock is released.
You also have to remember that if you take the RCU read lock just for this, there is potentially a cost to be paid later as you may cause extra grace period handling. David
