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From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>,
	jeremy@goop.org, jdelvare@suse.com, peterz@infradead.org,
	hpa@zytor.com, akataria@vmware.com, x86@kernel.org,
	rusty@rustcorp.com.au, virtualization@lists.linux-foundation.org,
	chrisw@sous-sol.org, mingo@redhat.com, david.vrabel@citrix.com,
	Douglas_Warzecha@dell.com, pali.rohar@gmail.com,
	boris.ostrovsky@oracle.com, tglx@linutronix.de,
	linux@roeck-us.net
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	[thread overview]
Message-ID: <1458563075-30298-3-git-send-email-jgross__16738.1709478379$1458563161$gmane$org@suse.com> (raw)
In-Reply-To: <1458563075-30298-1-git-send-email-jgross@suse.com>

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 <jgross@suse.com>
---
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


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  parent reply	other threads:[~2016-03-21 12:24 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1458563075-30298-1-git-send-email-jgross@suse.com>
2016-03-21 12:24 ` [PATCH v2 1/6] xen: sync xen header Juergen Gross
2016-03-21 12:24 ` Juergen Gross [this message]
2016-03-21 12:24 ` [PATCH v2 3/6] dcdbas: make use of smp_call_sync_on_phys_cpu() Juergen Gross
2016-03-21 12:24 ` [PATCH v2 4/6] hwmon: use smp_call_sync_on_phys_cpu() for dell-smm i8k Juergen Gross
2016-03-21 12:24 ` [PATCH v2 5/6] virt, sched: add cpu pinning to smp_call_sync_on_phys_cpu() Juergen Gross
2016-03-21 13:42   ` Jan Beulich
     [not found]   ` <56F0087202000078000DED9F@prv-mh.provo.novell.com>
2016-03-21 14:14     ` David Vrabel
     [not found]   ` <56F0087202000078000DED9F@suse.com>
2016-03-21 14:21     ` Juergen Gross
2016-03-21 12:24 ` [PATCH v2 6/6] xen: add xen_pin_vcpu() to support calling functions on a dedicated pcpu Juergen Gross

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