From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 162A2C433B4 for ; Sun, 11 Apr 2021 16:02:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD17161041 for ; Sun, 11 Apr 2021 16:02:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236370AbhDKQCz (ORCPT ); Sun, 11 Apr 2021 12:02:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:47510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235781AbhDKQCz (ORCPT ); Sun, 11 Apr 2021 12:02:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7563C61041; Sun, 11 Apr 2021 16:02:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618156958; bh=TJw038FUfkWYVYkaVmTwRcX8gW1Hrtqnv9rYV52PKrI=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=u0O8VVf8zy1PR2e25z0pJKozdIHbQJxa0IL1m2ShcIfesaiUzFtGRvrmSFOHMxSZs c8KgKfrywOtTgpLIESrsI/Cs4Vn9WkeLFbOe8EwqA2c1g1KPx8Wp9plKR8cHtNf3Qo IB2sDtZW0hA2ZzPXlkDLl7rGNxhR4rugm6fZ/8o3xXmWeFHiOtIOxfAo3Oue+bBzWz mt9+HpTF1RUm1fVm9AMrigkEsuBMzxUkJi9gampcR1e8Yd91Lwk++MgYmeehC82jRQ 85sY8hTUkTJ4v4kPjgzC7K/is4TbgtljQug0d3sWsK4KICaiyVwBkJjBGig+VFgbnz 6ZRNnnGckXNrA== Received: by mail-lj1-f180.google.com with SMTP id u9so12279562ljd.11; Sun, 11 Apr 2021 09:02:38 -0700 (PDT) X-Gm-Message-State: AOAM531nSr0g36iaPAgj0ngXej7VM5EWm65uy4sNdYL0dL1uZJxxR7xO tfjeLI+aP7Exnzdaovm0SOWTKhY0NJ9zpLEKzqc= X-Google-Smtp-Source: ABdhPJwBbonxz+gck6Cl5q5ziKW6g+nADEkFDKCdplfaEDt09lBYiLD8iBC6rcF3SKmLf+EgR6MFZf5Na1JfSr6rJDU= X-Received: by 2002:a2e:8182:: with SMTP id e2mr13024419ljg.238.1618156956863; Sun, 11 Apr 2021 09:02:36 -0700 (PDT) MIME-Version: 1.0 References: <1617201040-83905-1-git-send-email-guoren@kernel.org> <1617201040-83905-4-git-send-email-guoren@kernel.org> In-Reply-To: <1617201040-83905-4-git-send-email-guoren@kernel.org> From: Guo Ren Date: Mon, 12 Apr 2021 00:02:24 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 3/9] riscv: locks: Introduce ticket-based spinlock implementation To: Guo Ren Cc: linux-riscv , Linux Kernel Mailing List , linux-csky@vger.kernel.org, linux-arch , linuxppc-dev@lists.ozlabs.org, linux-xtensa@linux-xtensa.org, openrisc@lists.librecores.org, sparclinux , Guo Ren , Peter Zijlstra , Anup Patel , Arnd Bergmann Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Wed, Mar 31, 2021 at 10:32 PM wrote: > > From: Guo Ren > > This patch introduces a ticket lock implementation for riscv, along the > same lines as the implementation for arch/arm & arch/csky. > > We still use qspinlock as default. > > Signed-off-by: Guo Ren > Cc: Peter Zijlstra > Cc: Anup Patel > Cc: Arnd Bergmann > --- > arch/riscv/Kconfig | 7 ++- > arch/riscv/include/asm/spinlock.h | 84 +++++++++++++++++++++++++ > arch/riscv/include/asm/spinlock_types.h | 17 +++++ > 3 files changed, 107 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 67cc65ba1ea1..34d0276f01d5 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -34,7 +34,7 @@ config RISCV > select ARCH_WANT_FRAME_POINTERS > select ARCH_WANT_HUGE_PMD_SHARE if 64BIT > select ARCH_USE_QUEUED_RWLOCKS > - select ARCH_USE_QUEUED_SPINLOCKS > + select ARCH_USE_QUEUED_SPINLOCKS if !RISCV_TICKET_LOCK > select ARCH_USE_QUEUED_SPINLOCKS_XCHG32 > select CLONE_BACKWARDS > select CLINT_TIMER if !MMU > @@ -344,6 +344,11 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK > def_bool y > depends on NUMA > > +config RISCV_TICKET_LOCK > + bool "Ticket-based spin-locking" > + help > + Say Y here to use ticket-based spin-locking. > + > config RISCV_ISA_C > bool "Emit compressed instructions when building Linux" > default y > diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h > index a557de67a425..90b7eaa950cf 100644 > --- a/arch/riscv/include/asm/spinlock.h > +++ b/arch/riscv/include/asm/spinlock.h > @@ -7,7 +7,91 @@ > #ifndef _ASM_RISCV_SPINLOCK_H > #define _ASM_RISCV_SPINLOCK_H > > +#ifdef CONFIG_RISCV_TICKET_LOCK > +#ifdef CONFIG_32BIT > +#define __ASM_SLLIW "slli\t" > +#define __ASM_SRLIW "srli\t" > +#else > +#define __ASM_SLLIW "slliw\t" > +#define __ASM_SRLIW "srliw\t" > +#endif > + > +/* > + * Ticket-based spin-locking. > + */ > +static inline void arch_spin_lock(arch_spinlock_t *lock) > +{ > + arch_spinlock_t lockval; > + u32 tmp; > + > + asm volatile ( > + "1: lr.w %0, %2 \n" > + " mv %1, %0 \n" > + " addw %0, %0, %3 \n" > + " sc.w %0, %0, %2 \n" > + " bnez %0, 1b \n" > + : "=&r" (tmp), "=&r" (lockval), "+A" (lock->lock) > + : "r" (1 << TICKET_NEXT) > + : "memory"); > + > + smp_cond_load_acquire(&lock->tickets.owner, > + VAL == lockval.tickets.next); It's wrong, blew is fixup: diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h index fe98ad8ece51..2be627ceb9df 100644 --- a/arch/csky/include/asm/spinlock.h +++ b/arch/csky/include/asm/spinlock.h @@ -27,7 +27,8 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) : "r"(p), "r"(ticket_next) : "cc"); - smp_cond_load_acquire(&lock->tickets.owner, + if (lockval.owner != lockval.tickets.next) + smp_cond_load_acquire(&lock->tickets.owner, VAL == lockval.tickets.next); > +} > + > +static inline int arch_spin_trylock(arch_spinlock_t *lock) > +{ > + u32 tmp, contended, res; > + > + do { > + asm volatile ( > + " lr.w %0, %3 \n" > + __ASM_SRLIW "%1, %0, %5 \n" > + __ASM_SLLIW "%2, %0, %5 \n" > + " or %1, %2, %1 \n" > + " li %2, 0 \n" > + " sub %1, %1, %0 \n" > + " bnez %1, 1f \n" > + " addw %0, %0, %4 \n" > + " sc.w %2, %0, %3 \n" > + "1: \n" > + : "=&r" (tmp), "=&r" (contended), "=&r" (res), > + "+A" (lock->lock) > + : "r" (1 << TICKET_NEXT), "I" (TICKET_NEXT) > + : "memory"); > + } while (res); > + > + if (!contended) > + __atomic_acquire_fence(); > + > + return !contended; > +} > + > +static inline void arch_spin_unlock(arch_spinlock_t *lock) > +{ > + smp_store_release(&lock->tickets.owner, lock->tickets.owner + 1); > +} > + > +static inline int arch_spin_value_unlocked(arch_spinlock_t lock) > +{ > + return lock.tickets.owner == lock.tickets.next; > +} > + > +static inline int arch_spin_is_locked(arch_spinlock_t *lock) > +{ > + return !arch_spin_value_unlocked(READ_ONCE(*lock)); > +} > + > +static inline int arch_spin_is_contended(arch_spinlock_t *lock) > +{ > + struct __raw_tickets tickets = READ_ONCE(lock->tickets); > + > + return (tickets.next - tickets.owner) > 1; > +} > +#define arch_spin_is_contended arch_spin_is_contended > +#else /* CONFIG_RISCV_TICKET_LOCK */ > #include > +#endif /* CONFIG_RISCV_TICKET_LOCK */ > + > #include > > #endif /* _ASM_RISCV_SPINLOCK_H */ > diff --git a/arch/riscv/include/asm/spinlock_types.h b/arch/riscv/include/asm/spinlock_types.h > index d033a973f287..afbb19841d0f 100644 > --- a/arch/riscv/include/asm/spinlock_types.h > +++ b/arch/riscv/include/asm/spinlock_types.h > @@ -10,7 +10,24 @@ > # error "please don't include this file directly" > #endif > > +#ifdef CONFIG_RISCV_TICKET_LOCK > +#define TICKET_NEXT 16 > + > +typedef struct { > + union { > + u32 lock; > + struct __raw_tickets { > + /* little endian */ > + u16 owner; > + u16 next; > + } tickets; > + }; > +} arch_spinlock_t; > + > +#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } } > +#else > #include > +#endif > #include > > #endif /* _ASM_RISCV_SPINLOCK_TYPES_H */ > -- > 2.17.1 > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/