locktorture: Mark statistics data races

The lock_stress_stats structure's ->n_lock_fail and ->n_lock_acquired
fields are incremented and sampled locklessly using plain C-language
statements, which KCSAN objects to.  This commit therefore marks the
statistics gathering with data_race() to flag the intent.  While in
the area, this commit also reduces the number of accesses to the
->n_lock_acquired field, thus eliminating some possible check/use
confusion.

Signed-off-by: Paul E. McKenney <[email protected]>

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index b3adb40549bf37118b688a3689cf8cd731ba6227..313d5e613fbe6f1c82e64599141cb1a4d7520d33 100644 (file)
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -738,20 +738,22 @@ static int lock_torture_reader(void *arg)
 static void __torture_print_stats(char *page,
                                  struct lock_stress_stats *statp, bool write)
 {
+       long cur;
        bool fail = false;
        int i, n_stress;
-       long max = 0, min = statp ? statp[0].n_lock_acquired : 0;
+       long max = 0, min = statp ? data_race(statp[0].n_lock_acquired) : 0;
        long long sum = 0;
 
        n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress;
        for (i = 0; i < n_stress; i++) {
-               if (statp[i].n_lock_fail)
+               if (data_race(statp[i].n_lock_fail))
                        fail = true;
-               sum += statp[i].n_lock_acquired;
-               if (max < statp[i].n_lock_acquired)
-                       max = statp[i].n_lock_acquired;
-               if (min > statp[i].n_lock_acquired)
-                       min = statp[i].n_lock_acquired;
+               cur = data_race(statp[i].n_lock_acquired);
+               sum += cur;
+               if (max < cur)
+                       max = cur;
+               if (min > cur)
+                       min = cur;
        }
        page += sprintf(page,
                        "%s:  Total: %lld  Max/Min: %ld/%ld %s  Fail: %d %s\n",