Commit 96274561 authored by Uladzislau Rezki (Sony)'s avatar Uladzislau Rezki (Sony) Committed by Paul E. McKenney
Browse files

rcu/kvfree: Use READ_ONCE() when access to krcp->head 



The need_offload_krc() function is now lock-free, which gives the
compiler freedom to load old values from plain C-language loads from
the kfree_rcu_cpu struture's ->head pointer.  This commit therefore
applied READ_ONCE() to these loads.

Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent cc37d520

kernel/rcu/tree.c

+2 −2
Original line number Diff line number Diff line
@@ -3165,7 +3165,7 @@ need_offload_krc(struct kfree_rcu_cpu *krcp) 
		if (!list_empty(&krcp->bulk_head[i]))

			return true;



	return !!krcp->head;

	return !!READ_ONCE(krcp->head);

}



static void
@@ -3206,7 +3206,7 @@ static void kfree_rcu_monitor(struct work_struct *work) 
		// in that case the monitor work is rearmed.

		if ((!list_empty(&krcp->bulk_head[0]) && list_empty(&krwp->bulk_head_free[0])) ||

			(!list_empty(&krcp->bulk_head[1]) && list_empty(&krwp->bulk_head_free[1])) ||

				(krcp->head && !krwp->head_free)) {

				(READ_ONCE(krcp->head) && !krwp->head_free)) {



			// Channel 1 corresponds to the SLAB-pointer bulk path.

			// Channel 2 corresponds to vmalloc-pointer bulk path.