From: Will Deacon <will@kernel.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>, Ingo Molnar <mingo@redhat.com>,
Waiman Long <longman@redhat.com>,
Anton Blanchard <anton@ozlabs.org>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH 5/8] powerpc/64s: implement queued spinlocks and rwlocks
Date: Thu, 2 Jul 2020 09:02:19 +0100 [thread overview]
Message-ID: <20200702080219.GB16113@willie-the-truck> (raw)
Message-ID: <20200702080219.cApmL13a87AZe4lFEH4NdrObvbSgDdajgfE5NvKWZN8@z> (raw)
In-Reply-To: <20200702074839.1057733-6-npiggin@gmail.com>
On Thu, Jul 02, 2020 at 05:48:36PM +1000, Nicholas Piggin wrote:
> diff --git a/arch/powerpc/include/asm/qspinlock.h b/arch/powerpc/include/asm/qspinlock.h
> new file mode 100644
> index 000000000000..f84da77b6bb7
> --- /dev/null
> +++ b/arch/powerpc/include/asm/qspinlock.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_POWERPC_QSPINLOCK_H
> +#define _ASM_POWERPC_QSPINLOCK_H
> +
> +#include <asm-generic/qspinlock_types.h>
> +
> +#define _Q_PENDING_LOOPS (1 << 9) /* not tuned */
> +
> +#define smp_mb__after_spinlock() smp_mb()
> +
> +static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
> +{
> + smp_mb();
> + return atomic_read(&lock->val);
> +}
Why do you need the smp_mb() here?
Will
next prev parent reply other threads:[~2020-07-02 8:02 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 7:48 [PATCH 0/8] powerpc: queued spinlocks and rwlocks Nicholas Piggin
2020-07-02 7:48 ` [PATCH 1/8] powerpc/powernv: must include hvcall.h to get PAPR defines Nicholas Piggin
2020-07-02 7:48 ` Nicholas Piggin
2020-07-02 7:48 ` [PATCH 2/8] powerpc/pseries: use smp_rmb() in H_CONFER spin yield Nicholas Piggin
2020-07-02 7:48 ` Nicholas Piggin
2020-07-02 8:28 ` Peter Zijlstra
2020-07-02 8:28 ` Peter Zijlstra
2020-07-02 10:36 ` Nicholas Piggin
2020-07-02 10:36 ` Nicholas Piggin
2020-07-02 7:48 ` [PATCH 3/8] powerpc/pseries: move some PAPR paravirt functions to their own file Nicholas Piggin
2020-07-02 7:48 ` [PATCH 4/8] powerpc: move spinlock implementation to simple_spinlock Nicholas Piggin
2020-07-02 7:48 ` Nicholas Piggin
2020-07-02 7:48 ` [PATCH 5/8] powerpc/64s: implement queued spinlocks and rwlocks Nicholas Piggin
2020-07-02 8:02 ` Will Deacon [this message]
2020-07-02 8:02 ` Will Deacon
2020-07-02 10:25 ` Nicholas Piggin
2020-07-02 10:25 ` Nicholas Piggin
2020-07-02 10:35 ` Will Deacon
2020-07-02 10:47 ` Nicholas Piggin
2020-07-02 10:47 ` Nicholas Piggin
2020-07-02 10:48 ` Will Deacon
2020-07-02 10:48 ` Will Deacon
2020-07-03 10:52 ` Michael Ellerman
2020-07-03 10:52 ` Michael Ellerman
2020-07-02 7:48 ` [PATCH 6/8] powerpc/pseries: implement paravirt qspinlocks for SPLPAR Nicholas Piggin
2020-07-02 21:01 ` Waiman Long
2020-07-02 7:48 ` [PATCH 7/8] powerpc/qspinlock: optimised atomic_try_cmpxchg_lock that adds the lock hint Nicholas Piggin
2020-07-02 7:48 ` Nicholas Piggin
2020-07-02 7:48 ` [PATCH 8/8] powerpc/64s: remove paravirt from simple spinlocks (RFC only) Nicholas Piggin
2020-07-02 7:48 ` Nicholas Piggin
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