srcu: Add data_race() to ->srcu_lock_count and ->srcu_unlock_count arrays (b68c6146) · Commits · 戴 / test

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@kernel.org>

kernel/rcu/srcutree.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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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