diff options
| -rw-r--r-- | include/linux/rcupdate_trace.h | 4 | ||||
| -rw-r--r-- | kernel/rcu/tasks.h | 6 |
2 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h index d9015aac78c6..a6a6a3acab5a 100644 --- a/include/linux/rcupdate_trace.h +++ b/include/linux/rcupdate_trace.h @@ -50,6 +50,7 @@ static inline void rcu_read_lock_trace(void) struct task_struct *t = current; WRITE_ONCE(t->trc_reader_nesting, READ_ONCE(t->trc_reader_nesting) + 1); + barrier(); if (IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB) && t->trc_reader_special.b.need_mb) smp_mb(); // Pairs with update-side barriers @@ -72,6 +73,9 @@ static inline void rcu_read_unlock_trace(void) rcu_lock_release(&rcu_trace_lock_map); 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); 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 a0eaed522277..e583a2d47374 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -830,6 +830,12 @@ static void trc_read_check_handler(void *t_in) WRITE_ONCE(t->trc_reader_checked, true); goto reset_ipi; } + // If we are racing with an rcu_read_unlock_trace(), try again later. + if (unlikely(t->trc_reader_nesting < 0)) { + if (WARN_ON_ONCE(atomic_dec_and_test(&trc_n_readers_need_end))) + wake_up(&trc_wait); + goto reset_ipi; + } WRITE_ONCE(t->trc_reader_checked, true); // Get here if the task is in a read-side critical section. Set |