Re: [PATCH 02/12] powerpc: qspinlock: Mark accesses to qnode lock checks
From: "Nicholas Piggin" <npiggin@gmail.com>
Date: 2023-05-09 02:03:57
On Mon May 8, 2023 at 12:01 PM AEST, Rohan McLure wrote:
The powerpc implemenation of qspinlocks will both poll and spin on the bitlock guarding a qnode. Mark these accesses with READ_ONCE to convey to KCSAN that polling is intentional here.
Yeah, and obviously pairs with the WRITE_ONCE so comment isn't really necessary. Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Rohan McLure <redacted> --- arch/powerpc/lib/qspinlock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/arch/powerpc/lib/qspinlock.c b/arch/powerpc/lib/qspinlock.c index 9cf93963772b..579290d55abf 100644 --- a/arch/powerpc/lib/qspinlock.c +++ b/arch/powerpc/lib/qspinlock.c@@ -435,7 +435,7 @@ static __always_inline bool yield_to_prev(struct qspinlock *lock, struct qnode * smp_rmb(); /* See __yield_to_locked_owner comment */ - if (node->locked) { + if (READ_ONCE(node->locked)) { yield_to_preempted(prev_cpu, yield_count); spin_begin(); return preempted;@@ -584,7 +584,7 @@ static __always_inline void queued_spin_lock_mcs_queue(struct qspinlock *lock, b /* Wait for mcs node lock to be released */ spin_begin(); - while (node->locked) { + while (READ_ONCE(node->locked)) { spec_barrier(); if (yield_to_prev(lock, node, old, paravirt))-- 2.37.2