[RFC][PATCH 2/7] UBC: core (structures, API)

[Kirill Korotaev <dev@sw.ru>]

Core functionality and interfaces of UBC:
find/create beancounter, initialization,
charge/uncharge of resource, core objects' declarations.

Basic structures:
  ubparm           - resource description
  user_beancounter - set of resources, id, lock

Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@sw.ru>

---
 include/ub/beancounter.h |  157 ++++++++++++++++++
 init/main.c              |    4
 kernel/Makefile          |    1
 kernel/ub/Makefile       |    7
 kernel/ub/beancounter.c  |  398 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 567 insertions(+)

--- /dev/null	2006-07-18 14:52:43.075228448 +0400
+++ ./include/ub/beancounter.h	2006-08-10 14:58:27.000000000 +0400
@@ -0,0 +1,157 @@
+/*
+ *  include/ub/beancounter.h
+ *
+ *  Copyright (C) 2006 OpenVZ. SWsoft Inc
+ *
+ */
+
+#ifndef _LINUX_BEANCOUNTER_H
+#define _LINUX_BEANCOUNTER_H
+
+/*
+ *	Resource list.
+ */
+
+#define UB_RESOURCES	0
+
+struct ubparm {
+	/*
+	 * A barrier over which resource allocations are failed gracefully.
+	 * e.g. if the amount of consumed memory is over the barrier further
+	 * sbrk() or mmap() calls fail, the existing processes are not killed.
+	 */
+	unsigned long	barrier;
+	/* hard resource limit */
+	unsigned long	limit;
+	/* consumed resources */
+	unsigned long	held;
+	/* maximum amount of consumed resources through the last period */
+	unsigned long	maxheld;
+	/* minimum amount of consumed resources through the last period */
+	unsigned long	minheld;
+	/* count of failed charges */
+	unsigned long	failcnt;
+};
+
+/*
+ * Kernel internal part.
+ */
+
+#ifdef __KERNEL__
+
+#include <linux/config.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <asm/atomic.h>
+
+/*
+ * UB_MAXVALUE is essentially LONG_MAX declared in a cross-compiling safe form.
+ */
+#define UB_MAXVALUE	( (1UL << (sizeof(unsigned long)*8-1)) - 1)
+
+
+/*
+ *	Resource management structures
+ * Serialization issues:
+ *   beancounter list management is protected via ub_hash_lock
+ *   task pointers are set only for current task and only once
+ *   refcount is managed atomically
+ *   value and limit comparison and change are protected by per-ub spinlock
+ */
+
+struct user_beancounter
+{
+	atomic_t		ub_refcount;
+	spinlock_t		ub_lock;
+	uid_t			ub_uid;
+	struct hlist_node	hash;
+
+	struct user_beancounter	*parent;
+	void			*private_data;
+
+	/* resources statistics and settings */
+	struct ubparm		ub_parms[UB_RESOURCES];
+};
+
+enum severity { UB_BARRIER, UB_LIMIT, UB_FORCE };
+
+/* Flags passed to beancounter_findcreate() */
+#define UB_LOOKUP_SUB		0x01 /* Lookup subbeancounter */
+#define UB_ALLOC		0x02 /* May allocate new one */
+#define UB_ALLOC_ATOMIC		0x04 /* Allocate with GFP_ATOMIC */
+
+#define UB_HASH_SIZE		256
+
+#ifdef CONFIG_USER_RESOURCE
+extern struct hlist_head ub_hash[];
+extern spinlock_t ub_hash_lock;
+
+static inline void ub_adjust_held_minmax(struct user_beancounter *ub,
+		int resource)
+{
+	if (ub->ub_parms[resource].maxheld < ub->ub_parms[resource].held)
+		ub->ub_parms[resource].maxheld = ub->ub_parms[resource].held;
+	if (ub->ub_parms[resource].minheld > ub->ub_parms[resource].held)
+		ub->ub_parms[resource].minheld = ub->ub_parms[resource].held;
+}
+
+void ub_print_resource_warning(struct user_beancounter *ub, int res,
+		char *str, unsigned long val, unsigned long held);
+void ub_print_uid(struct user_beancounter *ub, char *str, int size);
+
+int  __charge_beancounter_locked(struct user_beancounter *ub,
+		int resource, unsigned long val, enum severity strict);
+void charge_beancounter_notop(struct user_beancounter *ub,
+		int resource, unsigned long val);
+int  charge_beancounter(struct user_beancounter *ub,
+		int resource, unsigned long val, enum severity strict);
+
+void __uncharge_beancounter_locked(struct user_beancounter *ub,
+		int resource, unsigned long val);
+void uncharge_beancounter_notop(struct user_beancounter *ub,
+		int resource, unsigned long val);
+void uncharge_beancounter(struct user_beancounter *ub,
+		int resource, unsigned long val);
+
+struct user_beancounter *beancounter_findcreate(uid_t uid,
+		struct user_beancounter *parent, int flags);
+
+static inline struct user_beancounter *get_beancounter(
+		struct user_beancounter *ub)
+{
+	atomic_inc(&ub->ub_refcount);
+	return ub;
+}
+
+void __put_beancounter(struct user_beancounter *ub);
+static inline void put_beancounter(struct user_beancounter *ub)
+{
+	__put_beancounter(ub);
+}
+
+void ub_init_early(void);
+void ub_init_late(void);
+void ub_init_proc(void);
+
+extern struct user_beancounter ub0;
+extern const char *ub_rnames[];
+
+#else /* CONFIG_USER_RESOURCE */
+
+#define beancounter_findcreate(id, p, f)		(NULL)
+#define get_beancounter(ub)				(NULL)
+#define put_beancounter(ub)				do { } while (0)
+#define __charge_beancounter_locked(ub, r, v, s)	(0)
+#define charge_beancounter(ub, r, v, s)			(0)
+#define charge_beancounter_notop(ub, r, v)		do { } while (0)
+#define __uncharge_beancounter_locked(ub, r, v)		do { } while (0)
+#define uncharge_beancounter(ub, r, v)			do { } while (0)
+#define uncharge_beancounter_notop(ub, r, v)		do { } while (0)
+#define ub_init_early()					do { } while (0)
+#define ub_init_late()					do { } while (0)
+#define ub_init_proc()					do { } while (0)
+
+#endif /* CONFIG_USER_RESOURCE */
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_BEANCOUNTER_H */
--- ./init/main.c.ubcore	2006-08-10 14:55:47.000000000 +0400
+++ ./init/main.c	2006-08-10 14:57:01.000000000 +0400
@@ -52,6 +52,8 @@
 #include <linux/debug_locks.h>
 #include <linux/lockdep.h>
 
+#include <ub/beancounter.h>
+
 #include <asm/io.h>
 #include <asm/bugs.h>
 #include <asm/setup.h>
@@ -470,6 +472,7 @@ asmlinkage void __init start_kernel(void
 	early_boot_irqs_off();
 	early_init_irq_lock_class();
 
+	ub_init_early();
 /*
  * Interrupts are still disabled. Do necessary setups, then
  * enable them
@@ -563,6 +566,7 @@ asmlinkage void __init start_kernel(void
 #endif
 	fork_init(num_physpages);
 	proc_caches_init();
+	ub_init_late();
 	buffer_init();
 	unnamed_dev_init();
 	key_init();
--- ./kernel/Makefile.ubcore	2006-08-10 14:55:47.000000000 +0400
+++ ./kernel/Makefile	2006-08-10 14:57:01.000000000 +0400
@@ -12,6 +12,7 @@ obj-y     = sched.o fork.o exec_domain.o
 
 obj-$(CONFIG_STACKTRACE) += stacktrace.o
 obj-y += time/
+obj-y += ub/
 obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
 obj-$(CONFIG_LOCKDEP) += lockdep.o
 ifeq ($(CONFIG_PROC_FS),y)
--- /dev/null	2006-07-18 14:52:43.075228448 +0400
+++ ./kernel/ub/Makefile	2006-08-10 14:57:01.000000000 +0400
@@ -0,0 +1,7 @@
+#
+# User resources part (UBC)
+#
+# Copyright (C) 2006 OpenVZ. SWsoft Inc
+#
+
+obj-$(CONFIG_USER_RESOURCE) += beancounter.o
--- /dev/null	2006-07-18 14:52:43.075228448 +0400
+++ ./kernel/ub/beancounter.c	2006-08-10 15:09:34.000000000 +0400
@@ -0,0 +1,398 @@
+/*
+ *  kernel/ub/beancounter.c
+ *
+ *  Copyright (C) 2006 OpenVZ. SWsoft Inc
+ *  Original code by (C) 1998      Alan Cox
+ *                       1998-2000 Andrey Savochkin <saw@saw.sw.com.sg>
+ */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#include <ub/beancounter.h>
+
+static kmem_cache_t *ub_cachep;
+static struct user_beancounter default_beancounter;
+static struct user_beancounter default_subbeancounter;
+
+static void init_beancounter_struct(struct user_beancounter *ub, uid_t id);
+
+struct user_beancounter ub0;
+
+const char *ub_rnames[] = {
+};
+
+#define ub_hash_fun(x) ((((x) >> 8) ^ (x)) & (UB_HASH_SIZE - 1))
+#define ub_subhash_fun(p, id) ub_hash_fun((p)->ub_uid + (id) * 17)
+
+struct hlist_head ub_hash[UB_HASH_SIZE];
+spinlock_t ub_hash_lock;
+
+EXPORT_SYMBOL(ub_hash);
+EXPORT_SYMBOL(ub_hash_lock);
+
+/*
+ *	Per user resource beancounting. Resources are tied to their luid.
+ *	The resource structure itself is tagged both to the process and
+ *	the charging resources (a socket doesn't want to have to search for
+ *	things at irq time for example). Reference counters keep things in
+ *	hand.
+ *
+ *	The case where a user creates resource, kills all his processes and
+ *	then starts new ones is correctly handled this way. The refcounters
+ *	will mean the old entry is still around with resource tied to it.
+ */
+
+struct user_beancounter *beancounter_findcreate(uid_t uid,
+		struct user_beancounter *p, int mask)
+{
+	struct user_beancounter *new_ub, *ub, *tmpl_ub;
+	unsigned long flags;
+	struct hlist_head *slot;
+	struct hlist_node *pos;
+
+	if (mask & UB_LOOKUP_SUB) {
+		WARN_ON(p == NULL);
+		tmpl_ub = &default_subbeancounter;
+		slot = &ub_hash[ub_subhash_fun(p, uid)];
+	} else {
+		WARN_ON(p != NULL);
+		tmpl_ub = &default_beancounter;
+		slot = &ub_hash[ub_hash_fun(uid)];
+	}
+	new_ub = NULL;
+
+retry:
+	spin_lock_irqsave(&ub_hash_lock, flags);
+	hlist_for_each_entry (ub, pos, slot, hash)
+		if (ub->ub_uid == uid && ub->parent == p)
+			break;
+
+	if (pos != NULL) {
+		get_beancounter(ub);
+		spin_unlock_irqrestore(&ub_hash_lock, flags);
+
+		if (new_ub != NULL) {
+			put_beancounter(new_ub->parent);
+			kmem_cache_free(ub_cachep, new_ub);
+		}
+		return ub;
+	}
+
+	if (!(mask & UB_ALLOC))
+		goto out_unlock;
+
+	if (new_ub != NULL)
+		goto out_install;
+
+	if (mask & UB_ALLOC_ATOMIC) {
+		new_ub = kmem_cache_alloc(ub_cachep, GFP_ATOMIC);
+		if (new_ub == NULL)
+			goto out_unlock;
+
+		memcpy(new_ub, tmpl_ub, sizeof(*new_ub));
+		init_beancounter_struct(new_ub, uid);
+		if (p)
+			new_ub->parent = get_beancounter(p);
+		goto out_install;
+	}
+
+	spin_unlock_irqrestore(&ub_hash_lock, flags);
+
+	new_ub = kmem_cache_alloc(ub_cachep, GFP_KERNEL);
+	if (new_ub == NULL)
+		goto out;
+
+	memcpy(new_ub, tmpl_ub, sizeof(*new_ub));
+	init_beancounter_struct(new_ub, uid);
+	if (p)
+		new_ub->parent = get_beancounter(p);
+	goto retry;
+
+out_install:
+	hlist_add_head(&new_ub->hash, slot);
+out_unlock:
+	spin_unlock_irqrestore(&ub_hash_lock, flags);
+out:
+	return new_ub;
+}
+
+EXPORT_SYMBOL(beancounter_findcreate);
+
+void ub_print_uid(struct user_beancounter *ub, char *str, int size)
+{
+	if (ub->parent != NULL)
+		snprintf(str, size, "%u.%u", ub->parent->ub_uid, ub->ub_uid);
+	else
+		snprintf(str, size, "%u", ub->ub_uid);
+}
+
+EXPORT_SYMBOL(ub_print_uid);
+
+void ub_print_resource_warning(struct user_beancounter *ub, int res,
+		char *str, unsigned long val, unsigned long held)
+{
+	char uid[64];
+
+	ub_print_uid(ub, uid, sizeof(uid));
+	printk(KERN_WARNING "UB %s %s warning: %s "
+			"(held %lu, fails %lu, val %lu)\n",
+			uid, ub_rnames[res], str,
+			(res < UB_RESOURCES ? ub->ub_parms[res].held : held),
+			(res < UB_RESOURCES ? ub->ub_parms[res].failcnt : 0),
+			val);
+}
+
+EXPORT_SYMBOL(ub_print_resource_warning);
+
+static inline void verify_held(struct user_beancounter *ub)
+{
+	int i;
+
+	for (i = 0; i < UB_RESOURCES; i++)
+		if (ub->ub_parms[i].held != 0)
+			ub_print_resource_warning(ub, i,
+					"resource is held on put", 0, 0);
+}
+
+void __put_beancounter(struct user_beancounter *ub)
+{
+	unsigned long flags;
+	struct user_beancounter *parent;
+
+again:
+	parent = ub->parent;
+	/* equevalent to atomic_dec_and_lock_irqsave() */
+	local_irq_save(flags);
+	if (likely(!atomic_dec_and_lock(&ub->ub_refcount, &ub_hash_lock))) {
+		if (unlikely(atomic_read(&ub->ub_refcount) < 0))
+			printk(KERN_ERR "UB: Bad ub refcount: ub=%p, "
+					"luid=%d, ref=%d\n",
+					ub, ub->ub_uid,
+					atomic_read(&ub->ub_refcount));
+		local_irq_restore(flags);
+		return;
+	}
+
+	if (unlikely(ub == &ub0)) {
+		printk(KERN_ERR "Trying to put ub0\n");
+		spin_unlock_irqrestore(&ub_hash_lock, flags);
+		return;
+	}
+
+	verify_held(ub);
+	hlist_del(&ub->hash);
+	spin_unlock_irqrestore(&ub_hash_lock, flags);
+
+	kmem_cache_free(ub_cachep, ub);
+
+	ub = parent;
+	if (ub != NULL)
+		goto again;
+}
+
+EXPORT_SYMBOL(__put_beancounter);
+
+/*
+ *	Generic resource charging stuff
+ */
+
+int __charge_beancounter_locked(struct user_beancounter *ub,
+		int resource, unsigned long val, enum severity strict)
+{
+	/*
+	 * ub_value <= UB_MAXVALUE, value <= UB_MAXVALUE, and only one addition
+	 * at the moment is possible so an overflow is impossible.  
+	 */
+	ub->ub_parms[resource].held += val;
+
+	switch (strict) {
+		case UB_BARRIER:
+			if (ub->ub_parms[resource].held >
+					ub->ub_parms[resource].barrier)
+				break;
+			/* fallthrough */
+		case UB_LIMIT:
+			if (ub->ub_parms[resource].held >
+					ub->ub_parms[resource].limit)
+				break;
+			/* fallthrough */
+		case UB_FORCE:
+			ub_adjust_held_minmax(ub, resource);
+			return 0;
+		default:
+			BUG();
+	}
+
+	ub->ub_parms[resource].failcnt++;
+	ub->ub_parms[resource].held -= val;
+	return -ENOMEM;
+}
+
+int charge_beancounter(struct user_beancounter *ub,
+		int resource, unsigned long val, enum severity strict)
+{
+	int retval;
+	struct user_beancounter *p, *q;
+	unsigned long flags;
+
+	retval = -EINVAL;
+	BUG_ON(val > UB_MAXVALUE);
+
+	local_irq_save(flags);
+	for (p = ub; p != NULL; p = p->parent) {
+		spin_lock(&p->ub_lock);
+		retval = __charge_beancounter_locked(p, resource, val, strict);
+		spin_unlock(&p->ub_lock);
+		if (retval)
+			goto unroll;
+	}
+out_restore:
+	local_irq_restore(flags);
+	return retval;
+
+unroll:
+	for (q = ub; q != p; q = q->parent) {
+		spin_lock(&q->ub_lock);
+		__uncharge_beancounter_locked(q, resource, val);
+		spin_unlock(&q->ub_lock);
+	}
+	goto out_restore;
+}
+
+EXPORT_SYMBOL(charge_beancounter);
+
+void charge_beancounter_notop(struct user_beancounter *ub,
+		int resource, unsigned long val)
+{
+	struct user_beancounter *p;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	for (p = ub; p->parent != NULL; p = p->parent) {
+		spin_lock(&p->ub_lock);
+		__charge_beancounter_locked(p, resource, val, UB_FORCE);
+		spin_unlock(&p->ub_lock);
+	}
+	local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL(charge_beancounter_notop);
+
+void __uncharge_beancounter_locked(struct user_beancounter *ub,
+		int resource, unsigned long val)
+{
+	if (unlikely(ub->ub_parms[resource].held < val)) {
+		ub_print_resource_warning(ub, resource,
+				"uncharging too much", val, 0);
+		val = ub->ub_parms[resource].held;
+	}
+	ub->ub_parms[resource].held -= val;
+	ub_adjust_held_minmax(ub, resource);
+}
+
+void uncharge_beancounter(struct user_beancounter *ub,
+		int resource, unsigned long val)
+{
+	unsigned long flags;
+	struct user_beancounter *p;
+
+	for (p = ub; p != NULL; p = p->parent) {
+		spin_lock_irqsave(&p->ub_lock, flags);
+		__uncharge_beancounter_locked(p, resource, val);
+		spin_unlock_irqrestore(&p->ub_lock, flags);
+	}
+}
+
+EXPORT_SYMBOL(uncharge_beancounter);
+
+void uncharge_beancounter_notop(struct user_beancounter *ub,
+		int resource, unsigned long val)
+{
+	struct user_beancounter *p;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	for (p = ub; p->parent != NULL; p = p->parent) {
+		spin_lock(&p->ub_lock);
+		__uncharge_beancounter_locked(p, resource, val);
+		spin_unlock(&p->ub_lock);
+	}
+	local_irq_restore(flags);
+}
+
+EXPORT_SYMBOL(uncharge_beancounter_notop);
+
+/*
+ *	Initialization
+ *
+ *	struct user_beancounter contains
+ *	 - limits and other configuration settings
+ *	 - structural fields: lists, spinlocks and so on.
+ *
+ *	Before these parts are initialized, the structure should be memset
+ *	to 0 or copied from a known clean structure.  That takes care of a lot
+ *	of fields not initialized explicitly.
+ */
+
+static void init_beancounter_struct(struct user_beancounter *ub, uid_t id)
+{
+	atomic_set(&ub->ub_refcount, 1);
+	spin_lock_init(&ub->ub_lock);
+	ub->ub_uid = id;
+}
+
+static void init_beancounter_nolimits(struct user_beancounter *ub)
+{
+	int k;
+
+	for (k = 0; k < UB_RESOURCES; k++) {
+		ub->ub_parms[k].limit = UB_MAXVALUE;
+		ub->ub_parms[k].barrier = UB_MAXVALUE;
+	}
+}
+
+static void init_beancounter_syslimits(struct user_beancounter *ub)
+{
+	int k;
+
+	for (k = 0; k < UB_RESOURCES; k++)
+		ub->ub_parms[k].barrier = ub->ub_parms[k].limit;
+}
+
+void __init ub_init_early(void)
+{
+	struct user_beancounter *ub;
+	struct hlist_head *slot;
+
+	ub = &ub0;
+
+	memset(ub, 0, sizeof(*ub));
+	init_beancounter_nolimits(ub);
+	init_beancounter_struct(ub, 0);
+
+	spin_lock_init(&ub_hash_lock);
+	slot = &ub_hash[ub_hash_fun(ub->ub_uid)];
+	hlist_add_head(&ub->hash, slot);
+}
+
+void __init ub_init_late(void)
+{
+	struct user_beancounter *ub;
+
+	ub_cachep = kmem_cache_create("user_beancounters",
+			sizeof(struct user_beancounter),
+			0, SLAB_HWCACHE_ALIGN, NULL, NULL);
+	if (ub_cachep == NULL)
+		panic("Can't create ubc caches\n");
+
+	ub = &default_beancounter;
+	memset(ub, 0, sizeof(default_beancounter));
+	init_beancounter_syslimits(ub);
+	init_beancounter_struct(ub, 0);
+
+	ub = &default_subbeancounter;
+	memset(ub, 0, sizeof(default_subbeancounter));
+	init_beancounter_nolimits(ub);
+	init_beancounter_struct(ub, 0);
+}