diff options
| -rw-r--r-- | include/linux/rcupdate.h | 11 | ||||
| -rw-r--r-- | include/linux/rcupdate_trace.h | 2 | ||||
| -rw-r--r-- | kernel/rcu/tasks.h | 22 |
3 files changed, 31 insertions, 4 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 1e728d544fc1..ebdfeead44e5 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -174,12 +174,19 @@ void synchronize_rcu_tasks(void); #define TRC_NEED_QS_CHECKED 0x2 // Task has been checked for needing quiescent state. u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new); +void rcu_tasks_trace_qs_blkd(struct task_struct *t); # define rcu_tasks_trace_qs(t) \ do { \ + int ___rttq_nesting = READ_ONCE((t)->trc_reader_nesting); \ + \ if (likely(!READ_ONCE((t)->trc_reader_special.b.need_qs)) && \ - likely(!READ_ONCE((t)->trc_reader_nesting))) \ + likely(!___rttq_nesting)) { \ rcu_trc_cmpxchg_need_qs((t), 0, TRC_NEED_QS_CHECKED); \ + } else if (___rttq_nesting && ___rttq_nesting != INT_MIN && \ + !READ_ONCE((t)->trc_reader_special.b.blocked)) { \ + rcu_tasks_trace_qs_blkd(t); \ + } \ } while (0) # else # define rcu_tasks_trace_qs(t) do { } while (0) @@ -188,7 +195,7 @@ u8 rcu_trc_cmpxchg_need_qs(struct task_struct *t, u8 old, u8 new); #define rcu_tasks_qs(t, preempt) \ do { \ rcu_tasks_classic_qs((t), (preempt)); \ - rcu_tasks_trace_qs((t)); \ + rcu_tasks_trace_qs(t); \ } while (0) # ifdef CONFIG_TASKS_RUDE_RCU diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h index 6f9c35817398..9bc8cbb33340 100644 --- a/include/linux/rcupdate_trace.h +++ b/include/linux/rcupdate_trace.h @@ -75,7 +75,7 @@ static inline void rcu_read_unlock_trace(void) nesting = READ_ONCE(t->trc_reader_nesting) - 1; barrier(); // Critical section before disabling. // Disable IPI-based setting of .need_qs. - WRITE_ONCE(t->trc_reader_nesting, INT_MIN); + WRITE_ONCE(t->trc_reader_nesting, INT_MIN + nesting); if (likely(!READ_ONCE(t->trc_reader_special.s)) || nesting) { WRITE_ONCE(t->trc_reader_nesting, nesting); return; // We assume shallow reader nesting. diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index fd4508af055e..bab75ec26bdb 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -1261,6 +1261,24 @@ void rcu_read_unlock_trace_special(struct task_struct *t) } EXPORT_SYMBOL_GPL(rcu_read_unlock_trace_special); +/* Add a newly blocked reader task to its CPU's list. */ +void rcu_tasks_trace_qs_blkd(struct task_struct *t) +{ + unsigned long flags; + struct rcu_tasks_percpu *rtpcp; + + local_irq_save(flags); + rtpcp = this_cpu_ptr(rcu_tasks_trace.rtpcpu); + raw_spin_lock_rcu_node(rtpcp); // irqs already disabled + t->trc_blkd_cpu = smp_processor_id(); + if (!rtpcp->rtp_blkd_tasks.next) + INIT_LIST_HEAD(&rtpcp->rtp_blkd_tasks); + list_add(&t->trc_blkd_node, &rtpcp->rtp_blkd_tasks); + t->trc_reader_special.b.blocked = true; + raw_spin_unlock_irqrestore_rcu_node(rtpcp, flags); +} +EXPORT_SYMBOL_GPL(rcu_tasks_trace_qs_blkd); + /* Add a task to the holdout list, if it is not already on the list. */ static void trc_add_holdout(struct task_struct *t, struct list_head *bhp) { @@ -1586,9 +1604,11 @@ static void rcu_tasks_trace_postgp(struct rcu_tasks *rtp) /* Report any needed quiescent state for this exiting task. */ static void exit_tasks_rcu_finish_trace(struct task_struct *t) { + union rcu_special trs = READ_ONCE(t->trc_reader_special); + rcu_trc_cmpxchg_need_qs(t, 0, TRC_NEED_QS_CHECKED); WARN_ON_ONCE(READ_ONCE(t->trc_reader_nesting)); - if (WARN_ON_ONCE(rcu_ld_need_qs(t) & TRC_NEED_QS)) + if (WARN_ON_ONCE(rcu_ld_need_qs(t) & TRC_NEED_QS) || trs.b.blocked) rcu_read_unlock_trace_special(t); else WRITE_ONCE(t->trc_reader_nesting, 0); |