From: "Nicholas Piggin" <npiggin@gmail.com>
To: "Rohan McLure" <rmclure@linux.ibm.com>, <linuxppc-dev@lists.ozlabs.org>
Cc: arnd@arndb.de
Subject: Re: [PATCH 02/12] powerpc: qspinlock: Mark accesses to qnode lock checks
Date: Tue, 09 May 2023 12:02:57 +1000 [thread overview]
Message-ID: <CSHDLPIYXIFS.2XHMUEQ2D0E52@wheely> (raw)
In-Reply-To: <20230508020120.218494-3-rmclure@linux.ibm.com>
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>
>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
> ---
> 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
next prev parent reply other threads:[~2023-05-09 2:03 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-08 2:01 [PATCH 00/12] powerpc: KCSAN fix warnings and mark accesses Rohan McLure
2023-05-08 2:01 ` [PATCH 01/12] powerpc: qspinlock: Fix qnode->locked value interpretation Rohan McLure
2023-05-09 2:01 ` Nicholas Piggin
2023-05-09 4:26 ` Rohan McLure
2023-05-08 2:01 ` [PATCH 02/12] powerpc: qspinlock: Mark accesses to qnode lock checks Rohan McLure
2023-05-09 2:02 ` Nicholas Piggin [this message]
2023-05-08 2:01 ` [PATCH 03/12] powerpc: qspinlock: Enforce qnode writes prior to publishing to queue Rohan McLure
2023-05-09 2:04 ` Nicholas Piggin
2023-05-09 5:26 ` Rohan McLure
2023-05-09 6:45 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 04/12] asm-generic/mmiowb: Mark accesses to fix KCSAN warnings Rohan McLure
2023-05-08 6:30 ` Arnd Bergmann
2023-05-08 15:44 ` [PATCH 4/12] " Gautam Menghani
2023-05-09 2:16 ` [PATCH 04/12] " Nicholas Piggin
2023-05-08 2:01 ` [PATCH 05/12] powerpc: Mark [h]ssr_valid accesses in check_return_regs_valid Rohan McLure
2023-05-09 2:17 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 06/12] powerpc: Mark accesses to power_save callback in arch_cpu_idle Rohan McLure
2023-05-09 2:21 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 07/12] powerpc: powernv: Fix KCSAN datarace warnings on idle_state contention Rohan McLure
2023-05-09 2:26 ` Nicholas Piggin
2023-05-10 2:00 ` Rohan McLure
2023-05-08 2:01 ` [PATCH 08/12] powerpc: Annotate accesses to ipi message flags Rohan McLure
2023-05-09 2:28 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 09/12] powerpc: Mark writes registering ipi to host cpu through kvm Rohan McLure
2023-05-09 2:30 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 10/12] powerpc: powernv: Annotate data races in opal events Rohan McLure
2023-05-09 2:31 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 11/12] powerpc: powernv: Annotate asynchronous access to opal tokens Rohan McLure
2023-05-08 2:01 ` [PATCH 12/12] powerpc: Mark asynchronous accesses to irq_data Rohan McLure
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