The following commit has been merged into the core/rcu branch of tip: Commit-ID: 654db05cee8186cf9438d94ef32a4f9ffe964e57 Gitweb: https://git.kernel.org/tip/654db05cee8186cf9438d94ef32a4f9ffe964e57 Author: Paul E. McKenney <paulmck@xxxxxxxxxx> AuthorDate: Sun, 09 Feb 2020 02:35:22 -08:00 Committer: Paul E. McKenney <paulmck@xxxxxxxxxx> CommitterDate: Mon, 27 Apr 2020 11:04:37 -07:00 rcu: Use data_race() for RCU expedited CPU stall-warning prints Although the accesses used to determine whether or not an expedited stall should be printed are an integral part of the concurrency algorithm governing use of the corresponding variables, the values that are simply printed are ancillary. As such, it is best to use data_race() for these accesses in order to provide the greatest latitude in the use of KCSAN for the other accesses that are an integral part of the algorithm. This commit therefore changes the relevant uses of READ_ONCE() to data_race(). Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- kernel/rcu/tree_exp.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 1a617b9..e1a7986 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -542,8 +542,8 @@ static void synchronize_rcu_expedited_wait(void) } pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n", jiffies - jiffies_start, rcu_state.expedited_sequence, - READ_ONCE(rnp_root->expmask), - ".T"[!!rnp_root->exp_tasks]); + data_race(rnp_root->expmask), + ".T"[!!data_race(rnp_root->exp_tasks)]); if (ndetected) { pr_err("blocking rcu_node structures:"); rcu_for_each_node_breadth_first(rnp) { @@ -553,8 +553,8 @@ static void synchronize_rcu_expedited_wait(void) continue; pr_cont(" l=%u:%d-%d:%#lx/%c", rnp->level, rnp->grplo, rnp->grphi, - READ_ONCE(rnp->expmask), - ".T"[!!rnp->exp_tasks]); + data_race(rnp->expmask), + ".T"[!!data_race(rnp->exp_tasks)]); } pr_cont("\n"); }
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