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5045 use atomic_{inc,dec}_* instead of atomic_add_*
@@ -957,11 +957,11 @@
 }
 
 #define DCB_RD_EXIT(cpu) {                                              \
         uint32_t *rp = &nca_gv[cpu].dcb_readers;                        \
                                                                         \
-        if (atomic_add_32_nv(rp, -1) == DCB_COUNT_USELOCK) {            \
+        if (atomic_dec_32_nv(rp) == DCB_COUNT_USELOCK) {                \
                 mutex_enter(&nca_dcb_lock);                             \
                 if (CV_HAS_WAITERS(&nca_dcb_wait)) {                    \
                         /* May be the last reader for this CPU */       \
                         cv_signal(&nca_dcb_wait);                       \
                 }                                                       \