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ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()

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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 acquire 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.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260911102152.YEtwkBj9@linutronix.de
Fixes: 68282dd930 ("ring-buffer: Fix resetting of shortest_full")
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Sebastian Andrzej Siewior 2026-09-11 12:21:52 +02:00 committed by Steven Rostedt
parent ed0aff60f8
commit 815e07c8fe
1 changed files with 6 additions and 7 deletions
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13
kernel/trace/ring_buffer.c
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@ -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);
}