rb_wake_up_waiters() is a irq_work callback which is initialized with
init_irq_work(). As such it will be invoked in thread context on
PREEMPT_RT. Invoking the callback in IRQ context on PREEMPT_RT is not an
option due its usage of wake_up_all().
Since this callback may run in thread context, it needs to acqurie
ring_buffer_per_cpu::reader_lock with disabling interrupts and may not
assume that they are disabled.
Use raw_spinlock_irqsave() to acquire ring_buffer_per_cpu::reader_lock.
Fixes: 68282dd930ea3 ("ring-buffer: Fix resetting of shortest_full")
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
---
kernel/trace/ring_buffer.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9c03a555a6ba2..681f9daf6fabb 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -904,14 +904,13 @@ static void rb_wake_up_waiters(struct irq_work *work)
struct ring_buffer_per_cpu *cpu_buffer =
container_of(rbwork, struct ring_buffer_per_cpu,
irq_work);
- /* Called from interrupt context */
- raw_spin_lock(&cpu_buffer->reader_lock);
- rbwork->wakeup_full = false;
- rbwork->full_waiters_pending = false;
+ scoped_guard(raw_spinlock_irqsave, &cpu_buffer->reader_lock) {
+ rbwork->wakeup_full = false;
+ rbwork->full_waiters_pending = false;
- /* Waking up all waiters, they will reset the shortest full */
- cpu_buffer->shortest_full = 0;
- raw_spin_unlock(&cpu_buffer->reader_lock);
+ /* Waking up all waiters, they will reset the shortest
full */
+ cpu_buffer->shortest_full = 0;
+ }
wake_up_all(&rbwork->full_waiters);
}
--
2.55.0
