From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758339Ab0LCASG (ORCPT ); Thu, 2 Dec 2010 19:18:06 -0500 Received: from smtp-out.google.com ([216.239.44.51]:44960 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758144Ab0LCARW (ORCPT ); Thu, 2 Dec 2010 19:17:22 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=XDzzTpm5CUhrLOiR9vPnllin4yWmugv2cQOv44SddYrJ04v48zYk+4MwA3M7GOkn2k ZHenWCCcOYFdZnyosF5Q== From: Michel Lespinasse To: linux-mm@kvack.org, Andrew Morton , Hugh Dickins , Rik van Riel , Peter Zijlstra , Nick Piggin , KOSAKI Motohiro Cc: linux-kernel@vger.kernel.org, Linus Torvalds Subject: [PATCH 4/6] rwsem: implement rwsem_is_contended() Date: Thu, 2 Dec 2010 16:16:50 -0800 Message-Id: <1291335412-16231-5-git-send-email-walken@google.com> X-Mailer: git-send-email 1.7.3.1 In-Reply-To: <1291335412-16231-1-git-send-email-walken@google.com> References: <1291335412-16231-1-git-send-email-walken@google.com> X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Trivial implementations for rwsem_is_contended() Signed-off-by: Michel Lespinasse --- arch/alpha/include/asm/rwsem.h | 5 +++++ arch/ia64/include/asm/rwsem.h | 5 +++++ arch/powerpc/include/asm/rwsem.h | 5 +++++ arch/s390/include/asm/rwsem.h | 5 +++++ arch/sh/include/asm/rwsem.h | 5 +++++ arch/sparc/include/asm/rwsem.h | 5 +++++ arch/x86/include/asm/rwsem.h | 5 +++++ arch/xtensa/include/asm/rwsem.h | 5 +++++ include/linux/rwsem-spinlock.h | 1 + lib/rwsem-spinlock.c | 12 ++++++++++++ 10 files changed, 53 insertions(+), 0 deletions(-) diff --git a/arch/alpha/include/asm/rwsem.h b/arch/alpha/include/asm/rwsem.h index 1570c0b..6183eec 100644 --- a/arch/alpha/include/asm/rwsem.h +++ b/arch/alpha/include/asm/rwsem.h @@ -255,5 +255,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* __KERNEL__ */ #endif /* _ALPHA_RWSEM_H */ diff --git a/arch/ia64/include/asm/rwsem.h b/arch/ia64/include/asm/rwsem.h index 215d545..e965b7a 100644 --- a/arch/ia64/include/asm/rwsem.h +++ b/arch/ia64/include/asm/rwsem.h @@ -179,4 +179,9 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* _ASM_IA64_RWSEM_H */ diff --git a/arch/powerpc/include/asm/rwsem.h b/arch/powerpc/include/asm/rwsem.h index 8447d89..69f5d13 100644 --- a/arch/powerpc/include/asm/rwsem.h +++ b/arch/powerpc/include/asm/rwsem.h @@ -179,5 +179,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return sem->count != 0; } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return sem->count < 0; +} + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_RWSEM_H */ diff --git a/arch/s390/include/asm/rwsem.h b/arch/s390/include/asm/rwsem.h index 423fdda..7d36f68 100644 --- a/arch/s390/include/asm/rwsem.h +++ b/arch/s390/include/asm/rwsem.h @@ -382,5 +382,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* __KERNEL__ */ #endif /* _S390_RWSEM_H */ diff --git a/arch/sh/include/asm/rwsem.h b/arch/sh/include/asm/rwsem.h index 06e2251..1f59516 100644 --- a/arch/sh/include/asm/rwsem.h +++ b/arch/sh/include/asm/rwsem.h @@ -184,5 +184,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* __KERNEL__ */ #endif /* _ASM_SH_RWSEM_H */ diff --git a/arch/sparc/include/asm/rwsem.h b/arch/sparc/include/asm/rwsem.h index a2b4302..88242e6 100644 --- a/arch/sparc/include/asm/rwsem.h +++ b/arch/sparc/include/asm/rwsem.h @@ -165,6 +165,11 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* __KERNEL__ */ #endif /* _SPARC64_RWSEM_H */ diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h index d1e41b0..a35521e 100644 --- a/arch/x86/include/asm/rwsem.h +++ b/arch/x86/include/asm/rwsem.h @@ -275,5 +275,10 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* __KERNEL__ */ #endif /* _ASM_X86_RWSEM_H */ diff --git a/arch/xtensa/include/asm/rwsem.h b/arch/xtensa/include/asm/rwsem.h index e39edf5..6c658cb 100644 --- a/arch/xtensa/include/asm/rwsem.h +++ b/arch/xtensa/include/asm/rwsem.h @@ -165,4 +165,9 @@ static inline int rwsem_is_locked(struct rw_semaphore *sem) return (sem->count != 0); } +static inline int rwsem_is_contended(struct rw_semaphore *sem) +{ + return (sem->count < 0); +} + #endif /* _XTENSA_RWSEM_H */ diff --git a/include/linux/rwsem-spinlock.h b/include/linux/rwsem-spinlock.h index bdfcc25..430de5b 100644 --- a/include/linux/rwsem-spinlock.h +++ b/include/linux/rwsem-spinlock.h @@ -69,6 +69,7 @@ extern void __up_read(struct rw_semaphore *sem); extern void __up_write(struct rw_semaphore *sem); extern void __downgrade_write(struct rw_semaphore *sem); extern int rwsem_is_locked(struct rw_semaphore *sem); +extern int rwsem_is_contended(struct rw_semaphore *sem); #endif /* __KERNEL__ */ #endif /* _LINUX_RWSEM_SPINLOCK_H */ diff --git a/lib/rwsem-spinlock.c b/lib/rwsem-spinlock.c index ffc9fc7..783753d 100644 --- a/lib/rwsem-spinlock.c +++ b/lib/rwsem-spinlock.c @@ -30,6 +30,18 @@ int rwsem_is_locked(struct rw_semaphore *sem) } EXPORT_SYMBOL(rwsem_is_locked); +int rwsem_is_contended(struct rw_semaphore *sem) +{ + int ret = 0; + unsigned long flags; + + if (spin_trylock_irqsave(&sem->wait_lock, flags)) { + ret = !list_empty(&sem->wait_list); + spin_unlock_irqrestore(&sem->wait_lock, flags); + } + return ret; +} + /* * initialise the semaphore */ -- 1.7.3.1