From 1e6d5f725738fff83e1c3cbdb8547142eb8820c2 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Mon, 16 Oct 2023 22:43:04 +1000 Subject: [PATCH] powerpc/qspinlock: Propagate sleepy if previous waiter is preempted The sleepy (aka lock-owner-is-preempted) condition is propagated down the queue by each waiter. If a waiter becomes preempted, it can no longer propagate sleepy. To allow subsequent waiters to yield to the lock owner, also check the lock owner in this case. Signed-off-by: Nicholas Piggin Tested-by: Shrikanth Hegde Reviewed-by: "Nysal Jan K.A" Signed-off-by: Michael Ellerman Link: https://msgid.link/20231016124305.139923-6-npiggin@gmail.com --- arch/powerpc/lib/qspinlock.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c index 6bb627e90a321..c68c2bd7b8534 100644 --- a/arch/powerpc/lib/qspinlock.c +++ b/arch/powerpc/lib/qspinlock.c @@ -384,7 +384,11 @@ static __always_inline bool yield_to_prev(struct qspinlock *lock, struct qnode * if (!pv_yield_propagate_owner) goto yield_prev; - if (node->sleepy) { + /* + * If the previous waiter was preempted it might not be able to + * propagate sleepy to us, so check the lock in that case too. + */ + if (node->sleepy || vcpu_is_preempted(prev_cpu)) { u32 val = READ_ONCE(lock->val); if (val & _Q_LOCKED_VAL) { -- 2.30.2