diff options
Diffstat (limited to 'kernel/rcu/tasks.h')
-rw-r--r-- | kernel/rcu/tasks.h | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 4147857007d7..a9e8ecb10860 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -806,22 +806,38 @@ reset_ipi: /* Callback function for scheduler to check locked-down task. */ static bool trc_inspect_reader(struct task_struct *t, void *arg) { - if (task_curr(t)) - return false; // It is running, so decline to inspect it. + int cpu = task_cpu(t); + bool in_qs = false; + + if (task_curr(t)) { + // If no chance of heavyweight readers, do it the hard way. + if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) + return false; + + // If heavyweight readers are enabled on the remote task, + // we can inspect its state despite its currently running. + // However, we cannot safely change its state. + if (!rcu_dynticks_zero_in_eqs(cpu, &t->trc_reader_nesting)) + return false; // No quiescent state, do it the hard way. + in_qs = true; + } else { + in_qs = likely(!t->trc_reader_nesting); + } // Mark as checked. Because this is called from the grace-period // kthread, also remove the task from the holdout list. t->trc_reader_checked = true; trc_del_holdout(t); - // If the task is in a read-side critical section, set up its - // its state so that it will awaken the grace-period kthread upon - // exit from that critical section. - if (unlikely(t->trc_reader_nesting)) { - atomic_inc(&trc_n_readers_need_end); // One more to wait on. - WARN_ON_ONCE(t->trc_reader_special.b.need_qs); - WRITE_ONCE(t->trc_reader_special.b.need_qs, true); - } + if (in_qs) + return true; // Already in quiescent state, done!!! + + // The task is in a read-side critical section, so set up its + // state so that it will awaken the grace-period kthread upon exit + // from that critical section. + atomic_inc(&trc_n_readers_need_end); // One more to wait on. + WARN_ON_ONCE(t->trc_reader_special.b.need_qs); + WRITE_ONCE(t->trc_reader_special.b.need_qs, true); return true; } |