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

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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: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Uladzislau Rezki (Sony) 2022-12-02 14:18:37 +01:00 committed by Paul E. McKenney
parent cc37d52076
commit 9627456101
1 changed files with 2 additions and 2 deletions
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kernel/rcu/tree.c
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@ -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.