Currently, the rcu_torture_writer() function checks that all required grace periods elapse during a stutter interval, which is a multi-second time period during which the test load is removed. However, this check is suppressed during early boot (that is, before init is spawned) in order to avoid false positives that otherwise occur due to heavy load on the single boot CPU. Unfortunately, this approach is insufficient. It is possible that the stutter interval might end just as init is spawned, so that early boot conditions prevailed during almost the entire stutter interval. This commit therefore takes a snapshot of boot-complete state just before the stutter interval, thus suppressing the check for failure to complete grace periods unless the entire stutter interval took place after early boot.
Unified · Split
| @@ -1070,6 +1070,7 @@ rcu_torture_fqs(void *arg) · 1069 unmodified lines | |||
| 1070 | static int | 1070 | static int |
| 1071 | rcu_torture_writer(void *arg) | 1071 | rcu_torture_writer(void *arg) |
| 1072 | { | 1072 | { |
| 1073 | bool boot_ended; | ||
| 1073 | bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal(); | 1074 | bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal(); |
| 1074 | unsigned long cookie; | 1075 | unsigned long cookie; |
| 1075 | int expediting = 0; | 1076 | int expediting = 0; |
| @@ -1239,12 +1240,13 @@ rcu_torture_writer(void *arg) · 163 unmodified lines | |||
| 1239 | !rcu_gp_is_normal(); | 1240 | !rcu_gp_is_normal(); |
| 1240 | } | 1241 | } |
| 1241 | rcu_torture_writer_state = RTWS_STUTTER; | 1242 | rcu_torture_writer_state = RTWS_STUTTER; |
| 1243 | boot_ended = rcu_inkernel_boot_has_ended(); | ||
| 1242 | stutter_waited = stutter_wait("rcu_torture_writer"); | 1244 | stutter_waited = stutter_wait("rcu_torture_writer"); |
| 1243 | if (stutter_waited && | 1245 | if (stutter_waited && |
| 1244 | !READ_ONCE(rcu_fwd_cb_nodelay) && | 1246 | !READ_ONCE(rcu_fwd_cb_nodelay) && |
| 1245 | !cur_ops->slow_gps && | 1247 | !cur_ops->slow_gps && |
| 1246 | !torture_must_stop() && | 1248 | !torture_must_stop() && |
| 1247 | rcu_inkernel_boot_has_ended()) | 1249 | boot_ended) |
| 1248 | for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) | 1250 | for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) |
| 1249 | if (list_empty(&rcu_tortures[i].rtort_free) && | 1251 | if (list_empty(&rcu_tortures[i].rtort_free) && |
| 1250 | rcu_access_pointer(rcu_torture_current) != | 1252 | rcu_access_pointer(rcu_torture_current) != |