From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 17/20] SMP: Implement on_cpu() Date: Mon, 09 Jul 2007 14:28:41 +0300 Message-ID: <46921BE9.4040801@qumranet.com> References: <11838956891287-git-send-email-avi@qumranet.com> <11838956893094-git-send-email-avi@qumranet.com> <4691D9C1.4050309@qumranet.com> <20070709071640.GB10864@one.firstfloor.org> <46920270.3080309@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: KVM , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andi Kleen Return-path: In-Reply-To: <46920270.3080309-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Andi Kleen wrote: >>> Well, smp_call_function_single() is arch specific whereas on_cpu() is >>> >> >> Yes, but the few instances should be relatively easy to fix. >> >> >>> generic code. Perhaps rename smp_call_function_single() to >>> __smp_call_function_single() and on_cpu() to >>> smp_call_function_single()? >>> >> >> The low level function checks for this anyways. Instead of erroring >> it should just DTRT. >> > > Okay. I'll make that change. > > Here it is (whitespace-mangled, don't try to apply). diff --git a/arch/i386/kernel/smpcommon.c b/arch/i386/kernel/smpcommon.c index 1868ae1..bbfe85a 100644 --- a/arch/i386/kernel/smpcommon.c +++ b/arch/i386/kernel/smpcommon.c @@ -47,7 +47,7 @@ int smp_call_function(void (*func) (void *info), void *info, int nonatomic, EXPORT_SYMBOL(smp_call_function); /** - * smp_call_function_single - Run a function on another CPU + * smp_call_function_single - Run a function on a specific CPU * @cpu: The target CPU. Cannot be the calling CPU. * @func: The function to run. This must be fast and non-blocking. * @info: An arbitrary pointer to pass to the function. @@ -66,9 +66,11 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, int ret; int me = get_cpu(); if (cpu == me) { - WARN_ON(1); + local_irq_disable(); + func(info); + local_irq_enable(); put_cpu(); - return -EBUSY; + return 0; } ret = smp_call_function_mask(cpumask_of_cpu(cpu), func, info, wait); diff --git a/arch/x86_64/kernel/smp.c b/arch/x86_64/kernel/smp.c index 2ff4685..e6e5017 100644 --- a/arch/x86_64/kernel/smp.c +++ b/arch/x86_64/kernel/smp.c @@ -357,7 +357,7 @@ __smp_call_function_single(int cpu, void (*func) (void *info), void *info, } /* - * smp_call_function_single - Run a function on another CPU + * smp_call_function_single - Run a function on a specific CPU * @func: The function to run. This must be fast and non-blocking. * @info: An arbitrary pointer to pass to the function. * @nonatomic: Currently unused. @@ -372,16 +372,19 @@ __smp_call_function_single(int cpu, void (*func) (void *info), void *info, int smp_call_function_single (int cpu, void (*func) (void *info), void *info, int nonatomic, int wait) { + /* Can deadlock when called with interrupts disabled */ + WARN_ON(irqs_disabled()); + /* prevent preemption and reschedule on another processor */ int me = get_cpu(); if (cpu == me) { + local_irq_disable(); + func(info); + local_irq_enable(); put_cpu(); return 0; } - /* Can deadlock when called with interrupts disabled */ - WARN_ON(irqs_disabled()); - spin_lock_bh(&call_lock); __smp_call_function_single(cpu, func, info, nonatomic, wait); spin_unlock_bh(&call_lock); diff --git a/include/linux/smp.h b/include/linux/smp.h index 613edd2..ed38a3d 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -118,7 +118,11 @@ static inline void smp_send_reschedule(int cpu) { } static inline int smp_call_function_single(int cpuid, void (*func) (void *info), void *info, int retry, int wait) { - return -EBUSY; + WARN_ON(cpuid != 0); + local_irq_disable(); + func(info); + local_irq_enable(); + return 0; } #endif /* !SMP */ If there are no objections, I will push it (split up) through my kvm updates patchset, as other kvm patches depend on it. I will submit patches to other archs through the arch maintainers as kvm doesn't care about them yet. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/