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

Kirill Korotaev
2006-08-16T15:35:12Z

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);
+}