From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> The srcu_node structure's ->srcu_gp_seq_needed_exp field is accessed locklessly, so updates must use WRITE_ONCE(). This commit therefore adds the needed WRITE_ONCE() invocations. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely. Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/srcutree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 657e6a7..b1edac9 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -550,7 +550,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) snp->srcu_have_cbs[idx] = gpseq; rcu_seq_set_state(&snp->srcu_have_cbs[idx], 1); if (ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, gpseq)) - snp->srcu_gp_seq_needed_exp = gpseq; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, gpseq); mask = snp->srcu_data_have_cbs[idx]; snp->srcu_data_have_cbs[idx] = 0; spin_unlock_irq_rcu_node(snp); @@ -660,7 +660,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, if (snp == sdp->mynode) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s)) - snp->srcu_gp_seq_needed_exp = s; + WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(snp, flags); } -- 2.9.5
