padata: Generic parallelization/serialization interface

This patch introduces an interface to process data objects
in parallel. The parallelized objects return after serialization
in the same order as they were before the parallelization.
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/linux/padata.h

+/*
+ * padata.h - header for the padata parallelization interface
+ *
+ * Copyright (C) 2008, 2009 secunet Security Networks AG
+ * Copyright (C) 2008, 2009 Steffen Klassert <steffen.klassert@secunet.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PADATA_H
+#define PADATA_H
+
+#include <linux/workqueue.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+
+struct padata_priv {
+	struct list_head	list;
+	struct parallel_data	*pd;
+	int			cb_cpu;
+	int			seq_nr;
+	int			info;
+	void                    (*parallel)(struct padata_priv *padata);
+	void                    (*serial)(struct padata_priv *padata);
+};
+
+struct padata_list {
+	struct list_head        list;
+	spinlock_t              lock;
+};
+
+struct padata_queue {
+	struct padata_list	parallel;
+	struct padata_list	reorder;
+	struct padata_list	serial;
+	struct work_struct	pwork;
+	struct work_struct	swork;
+	struct parallel_data    *pd;
+	atomic_t		num_obj;
+	int			cpu_index;
+};
+
+struct parallel_data {
+	struct padata_instance	*pinst;
+	struct padata_queue	*queue;
+	atomic_t		seq_nr;
+	atomic_t		reorder_objects;
+	atomic_t                refcnt;
+	unsigned int		max_seq_nr;
+	cpumask_var_t		cpumask;
+	spinlock_t              lock;
+};
+
+struct padata_instance {
+	struct notifier_block   cpu_notifier;
+	struct workqueue_struct *wq;
+	struct parallel_data	*pd;
+	cpumask_var_t           cpumask;
+	struct mutex		lock;
+	u8			flags;
+#define	PADATA_INIT		1
+#define	PADATA_RESET		2
+};
+
+extern struct padata_instance *padata_alloc(const struct cpumask *cpumask,
+					    struct workqueue_struct *wq);
+extern void padata_free(struct padata_instance *pinst);
+extern int padata_do_parallel(struct padata_instance *pinst,
+			      struct padata_priv *padata, int cb_cpu);
+extern void padata_do_serial(struct padata_priv *padata);
+extern int padata_set_cpumask(struct padata_instance *pinst,
+			      cpumask_var_t cpumask);
+extern int padata_add_cpu(struct padata_instance *pinst, int cpu);
+extern int padata_remove_cpu(struct padata_instance *pinst, int cpu);
+extern void padata_start(struct padata_instance *pinst);
+extern void padata_stop(struct padata_instance *pinst);
+#endif

init/Kconfig

@@ -1252,4 +1252,8 @@ source "block/Kconfig"
 config PREEMPT_NOTIFIERS
 	bool
 
+config PADATA
+	depends on SMP
+	bool
+
 source "kernel/Kconfig.locks"

kernel/Makefile

@@ -100,6 +100,7 @@ obj-$(CONFIG_SLOW_WORK_DEBUG) += slow-work-debugfs.o
 obj-$(CONFIG_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
+obj-$(CONFIG_PADATA) += padata.o
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is