Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755990AbcCUM2c (ORCPT ); Mon, 21 Mar 2016 08:28:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:45157 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662AbcCUMYq (ORCPT ); Mon, 21 Mar 2016 08:24:46 -0400 From: Juergen Gross To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Cc: konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, mingo@redhat.com, peterz@infradead.org, Douglas_Warzecha@dell.com, pali.rohar@gmail.com, jdelvare@suse.com, linux@roeck-us.net, tglx@linutronix.de, hpa@zytor.com, jeremy@goop.org, chrisw@sous-sol.org, akataria@vmware.com, rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org, x86@kernel.org, Juergen Gross Subject: [PATCH v2 2/6] smp: add function to execute a function synchronously on a physical cpu Date: Mon, 21 Mar 2016 13:24:31 +0100 Message-Id: <1458563075-30298-3-git-send-email-jgross@suse.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1458563075-30298-1-git-send-email-jgross@suse.com> References: <1458563075-30298-1-git-send-email-jgross@suse.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2849 Lines: 99 On some hardware models (e.g. Dell Studio 1555 laptop) some hardware related functions (e.g. SMIs) are to be executed on physical cpu 0 only. Instead of open coding such a functionality multiple times in the kernel add a service function for this purpose. This will enable the possibility to take special measures in virtualized environments like Xen, too. Signed-off-by: Juergen Gross --- V2: instead of manipulating the allowed set of cpus use cpu specific workqueue as requested by Peter Zijlstra --- include/linux/smp.h | 2 ++ kernel/smp.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ kernel/up.c | 9 +++++++++ 3 files changed, 55 insertions(+) diff --git a/include/linux/smp.h b/include/linux/smp.h index c441407..fc9d21b 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -196,4 +196,6 @@ extern void arch_enable_nonboot_cpus_end(void); void smp_setup_processor_id(void); +int smp_call_sync_on_phys_cpu(unsigned int cpu, int (*func)(void *), void *par); + #endif /* __LINUX_SMP_H */ diff --git a/kernel/smp.c b/kernel/smp.c index 7416544..62da74b 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -739,3 +739,47 @@ void wake_up_all_idle_cpus(void) preempt_enable(); } EXPORT_SYMBOL_GPL(wake_up_all_idle_cpus); + +/** + * smp_call_sync_on_phys_cpu - Call a function on a specific physical cpu + * + * Used to call a function on a specific physical cpu. Even if the specified + * cpu isn't the current one, return only after the called function has + * returned. + */ +struct smp_sync_call_struct { + struct work_struct work; + struct completion done; + int (*func)(void *); + void *data; + int ret; +}; + +static void smp_call_sync_callback(struct work_struct *work) +{ + struct smp_sync_call_struct *sscs; + + sscs = container_of(work, struct smp_sync_call_struct, work); + sscs->ret = sscs->func(sscs->data); + + complete(&sscs->done); +} + +int smp_call_sync_on_phys_cpu(unsigned int cpu, int (*func)(void *), void *par) +{ + struct smp_sync_call_struct sscs = { + .work = __WORK_INITIALIZER(sscs.work, smp_call_sync_callback), + .done = COMPLETION_INITIALIZER_ONSTACK(sscs.done), + .func = func, + .data = par, + }; + + if (cpu >= nr_cpu_ids) + return -EINVAL; + + queue_work_on(cpu, system_wq, &sscs.work); + wait_for_completion(&sscs.done); + + return sscs.ret; +} +EXPORT_SYMBOL_GPL(smp_call_sync_on_phys_cpu); diff --git a/kernel/up.c b/kernel/up.c index 1760bf3..afd395c 100644 --- a/kernel/up.c +++ b/kernel/up.c @@ -82,3 +82,12 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), preempt_enable(); } EXPORT_SYMBOL(on_each_cpu_cond); + +int smp_call_sync_on_phys_cpu(unsigned int cpu, int (*func)(void *), void *par) +{ + if (cpu != 0) + return -EINVAL; + + return func(par); +} +EXPORT_SYMBOL_GPL(smp_call_sync_on_phys_cpu); -- 2.6.2