The following commit has been merged into the core/rcu branch of tip: Commit-ID: b68c6146512d92f6d570d26e1873497ade2cc4cb Gitweb: https://git.kernel.org/tip/b68c6146512d92f6d570d26e1873497ade2cc4cb Author: Paul E. McKenney <paulmck@xxxxxxxxxx> AuthorDate: Fri, 03 Jan 2020 16:36:59 -08:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> CommitterDate: Mon, 27 Apr 2020 11:01:16 -07:00 srcu: Add data_race() to ->srcu_lock_count and ->srcu_unlock_count arrays The srcu_data structure's ->srcu_lock_count and ->srcu_unlock_count arrays are read and written locklessly, so this commit adds the data_race() to the diagnostic-print loads from these arrays in order mark them as known and approved data-racy accesses. This data race was reported by KCSAN. Not appropriate for backporting due to failure being unlikely and due to this being used only by rcutorture. Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/srcutree.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index ba2b751..6d3ef70 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1281,8 +1281,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) struct srcu_data *sdp; sdp = per_cpu_ptr(ssp->sda, cpu); - u0 = sdp->srcu_unlock_count[!idx]; - u1 = sdp->srcu_unlock_count[idx]; + u0 = data_race(sdp->srcu_unlock_count[!idx]); + u1 = data_race(sdp->srcu_unlock_count[idx]); /* * Make sure that a lock is always counted if the corresponding @@ -1290,8 +1290,8 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf) */ smp_rmb(); - l0 = sdp->srcu_lock_count[!idx]; - l1 = sdp->srcu_lock_count[idx]; + l0 = data_race(sdp->srcu_lock_count[!idx]); + l1 = data_race(sdp->srcu_lock_count[idx]); c0 = l0 - u0; c1 = l1 - u1;
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