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| author | Paul E. McKenney <paulmck@kernel.org> | 2021-07-20 06:16:27 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2021-09-13 16:32:45 -0700 |
| commit | 2431774f04d1050292054c763070021bade7b151 (patch) | |
| tree | 70d1c1de7127d9e8585fa95186332c9e47b6d060 /kernel/rcu | |
| parent | 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f (diff) | |
| download | lwn-2431774f04d1050292054c763070021bade7b151.tar.gz lwn-2431774f04d1050292054c763070021bade7b151.zip | |
rcu: Mark accesses to rcu_state.n_force_qs
This commit marks accesses to the rcu_state.n_force_qs. These data
races are hard to make happen, but syzkaller was equal to the task.
Reported-by: syzbot+e08a83a1940ec3846cd5@syzkaller.appspotmail.com
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index bce848e50512..c89f5e6c4154 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1907,7 +1907,7 @@ static void rcu_gp_fqs(bool first_time) struct rcu_node *rnp = rcu_get_root(); WRITE_ONCE(rcu_state.gp_activity, jiffies); - rcu_state.n_force_qs++; + WRITE_ONCE(rcu_state.n_force_qs, rcu_state.n_force_qs + 1); if (first_time) { /* Collect dyntick-idle snapshots. */ force_qs_rnp(dyntick_save_progress_counter); @@ -2550,7 +2550,7 @@ static void rcu_do_batch(struct rcu_data *rdp) /* Reset ->qlen_last_fqs_check trigger if enough CBs have drained. */ if (count == 0 && rdp->qlen_last_fqs_check != 0) { rdp->qlen_last_fqs_check = 0; - rdp->n_force_qs_snap = rcu_state.n_force_qs; + rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs); } else if (count < rdp->qlen_last_fqs_check - qhimark) rdp->qlen_last_fqs_check = count; @@ -2898,10 +2898,10 @@ static void __call_rcu_core(struct rcu_data *rdp, struct rcu_head *head, } else { /* Give the grace period a kick. */ rdp->blimit = DEFAULT_MAX_RCU_BLIMIT; - if (rcu_state.n_force_qs == rdp->n_force_qs_snap && + if (READ_ONCE(rcu_state.n_force_qs) == rdp->n_force_qs_snap && rcu_segcblist_first_pend_cb(&rdp->cblist) != head) rcu_force_quiescent_state(); - rdp->n_force_qs_snap = rcu_state.n_force_qs; + rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs); rdp->qlen_last_fqs_check = rcu_segcblist_n_cbs(&rdp->cblist); } } @@ -4128,7 +4128,7 @@ int rcutree_prepare_cpu(unsigned int cpu) /* Set up local state, ensuring consistent view of global state. */ raw_spin_lock_irqsave_rcu_node(rnp, flags); rdp->qlen_last_fqs_check = 0; - rdp->n_force_qs_snap = rcu_state.n_force_qs; + rdp->n_force_qs_snap = READ_ONCE(rcu_state.n_force_qs); rdp->blimit = blimit; rdp->dynticks_nesting = 1; /* CPU not up, no tearing. */ rcu_dynticks_eqs_online(); |