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Subject[PATCH 3/7] BC: beancounters core (API)
Core functionality and interfaces of BC:
find/create beancounter, initialization,
charge/uncharge of resource, core objects' declarations.

Basic structures:
bc_resource_parm - resource description
beancounter - set of resources, id, lock

Signed-off-by: Pavel Emelianov <xemul@sw.ru>
Signed-off-by: Kirill Korotaev <dev@sw.ru>

---
include/bc/beancounter.h | 150 +++++++++++++++++++++++++++
include/linux/types.h | 16 ++
init/main.c | 4
kernel/Makefile | 1
kernel/bc/Makefile | 7 +
kernel/bc/beancounter.c | 256 +++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 434 insertions(+)
--- /dev/null 2006-07-18 14:52:43.075228448 +0400
+++ ./include/bc/beancounter.h 2006-08-28 12:47:52.000000000 +0400
@@ -0,0 +1,150 @@
+/*
+ * include/bc/beancounter.h
+ *
+ * Copyright (C) 2006 OpenVZ. SWsoft Inc
+ *
+ */
+
+#ifndef _LINUX_BEANCOUNTER_H
+#define _LINUX_BEANCOUNTER_H
+
+/*
+ * Resource list.
+ */
+
+#define BC_RESOURCES 0
+
+struct bc_resource_parm {
+ unsigned long barrier; /* 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 limit; /* hard resource limit */
+ unsigned long held; /* consumed resources */
+ unsigned long maxheld; /* maximum amount of consumed resources */
+ unsigned long minheld; /* minumum amount of consumed resources */
+ unsigned long failcnt; /* count of failed charges */
+};
+
+/*
+ * Kernel internal part.
+ */
+
+#ifdef __KERNEL__
+
+#include <linux/spinlock.h>
+#include <linux/list.h>
+#include <asm/atomic.h>
+
+#define BC_MAXVALUE LONG_MAX
+
+/*
+ * Resource management structures
+ * Serialization issues:
+ * beancounter list management is protected via bc_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-bc spinlock
+ */
+
+struct beancounter {
+ atomic_t bc_refcount;
+ spinlock_t bc_lock;
+ bcid_t bc_id;
+ struct hlist_node hash;
+
+ /* resources statistics and settings */
+ struct bc_resource_parm bc_parms[BC_RESOURCES];
+};
+
+enum bc_severity { BC_BARRIER, BC_LIMIT, BC_FORCE };
+
+/* Flags passed to beancounter_findcreate() */
+#define BC_LOOKUP 0x00
+#define BC_ALLOC 0x01 /* May allocate new one */
+#define BC_ALLOC_ATOMIC 0x02 /* Allocate with GFP_ATOMIC */
+
+#define BC_HASH_BITS 8
+#define BC_HASH_SIZE (1 << BC_HASH_BITS)
+
+#ifdef CONFIG_BEANCOUNTERS
+
+/*
+ * This function tunes minheld and maxheld values for a given
+ * resource when held value changes
+ */
+static inline void bc_adjust_held_minmax(struct beancounter *bc,
+ int resource)
+{
+ struct bc_resource_parm *parm;
+
+ parm = &bc->bc_parms[resource];
+ if (parm->maxheld < parm->held)
+ parm->maxheld = parm->held;
+ if (parm->minheld > parm->held)
+ parm->minheld = parm->held;
+}
+
+int __must_check bc_charge_locked(struct beancounter *bc,
+ int res, unsigned long val, enum bc_severity strict);
+int __must_check bc_charge(struct beancounter *bc,
+ int res, unsigned long val, enum bc_severity strict);
+
+void bc_uncharge_locked(struct beancounter *bc, int res, unsigned long val);
+void bc_uncharge(struct beancounter *bc, int res, unsigned long val);
+
+struct beancounter *beancounter_findcreate(bcid_t id, int mask);
+
+static inline struct beancounter *get_beancounter(struct beancounter *bc)
+{
+ atomic_inc(&bc->bc_refcount);
+ return bc;
+}
+
+void put_beancounter(struct beancounter *bc);
+
+void bc_init_early(void);
+void bc_init_late(void);
+void bc_init_proc(void);
+
+extern struct beancounter init_bc;
+extern const char *bc_rnames[];
+
+#else /* CONFIG_BEANCOUNTERS */
+
+#define beancounter_findcreate(id, f) (NULL)
+#define get_beancounter(bc) (NULL)
+#define put_beancounter(bc) do { } while (0)
+
+static inline __must_check int bc_charge_locked(struct beancounter *bc,
+ int res, unsigned long val, enum bc_severity strict)
+{
+ return 0;
+}
+
+static inline __must_check int bc_charge(struct beancounter *bc,
+ int res, unsigned long val, enum bc_severity strict)
+{
+ return 0;
+}
+
+static inline void bc_uncharge_locked(struct beancounter *bc, int res,
+ unsigned long val)
+{
+}
+
+static inline void bc_uncharge(struct beancounter *bc, int res,
+ unsigned long val)
+{
+}
+
+#define bc_init_early() do { } while (0)
+#define bc_init_late() do { } while (0)
+#define bc_init_proc() do { } while (0)
+
+#endif /* CONFIG_BEANCOUNTERS */
+#endif /* __KERNEL__ */
+
+#endif /* _LINUX_BEANCOUNTER_H */
--- ./include/linux/types.h.bccore 2006-08-28 12:20:13.000000000 +0400
+++ ./include/linux/types.h 2006-08-28 12:44:13.000000000 +0400
@@ -40,6 +40,21 @@ typedef __kernel_gid32_t gid_t;
typedef __kernel_uid16_t uid16_t;
typedef __kernel_gid16_t gid16_t;

+/*
+ * Type of beancounter id (CONFIG_BEANCOUNTERS)
+ *
+ * The ancient Unix implementations of this kind of resource management and
+ * security are built around setluid() which sets a uid value that cannot
+ * be changed again and is normally used for security purposes. That
+ * happened to be a uid_t and in simple setups at login uid = luid = euid
+ * would be the norm.
+ *
+ * Thus the Linux one happens to be a uid_t. It could be something else but
+ * for the "container per user" model whatever a container is must be able
+ * to hold all possible uid_t values. Alan Cox.
+ */
+typedef uid_t bcid_t;
+
#ifdef CONFIG_UID16
/* This is defined by include/asm-{arch}/posix_types.h */
typedef __kernel_old_uid_t old_uid_t;
@@ -52,6 +67,7 @@ typedef __kernel_old_gid_t old_gid_t;
#else
typedef __kernel_uid_t uid_t;
typedef __kernel_gid_t gid_t;
+typedef __kernel_uid_t bcid_t;
#endif /* __KERNEL__ */

#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
--- ./init/main.c.bccore 2006-08-28 12:20:13.000000000 +0400
+++ ./init/main.c 2006-08-28 12:43:34.000000000 +0400
@@ -52,6 +52,8 @@
#include <linux/debug_locks.h>
#include <linux/lockdep.h>

+#include <bc/beancounter.h>
+
#include <asm/io.h>
#include <asm/bugs.h>
#include <asm/setup.h>
@@ -495,6 +497,7 @@ asmlinkage void __init start_kernel(void
early_boot_irqs_off();
early_init_irq_lock_class();

+ bc_init_early();
/*
* Interrupts are still disabled. Do necessary setups, then
* enable them
@@ -587,6 +590,7 @@ asmlinkage void __init start_kernel(void
#endif
fork_init(num_physpages);
proc_caches_init();
+ bc_init_late();
buffer_init();
unnamed_dev_init();
key_init();
--- ./kernel/Makefile.bccore 2006-08-28 12:20:13.000000000 +0400
+++ ./kernel/Makefile 2006-08-28 12:43:34.000000000 +0400
@@ -12,6 +12,7 @@ obj-y = sched.o fork.o exec_domain.o

obj-$(CONFIG_STACKTRACE) += stacktrace.o
obj-y += time/
+obj-y += bc/
obj-$(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/bc/Makefile 2006-08-28 12:43:34.000000000 +0400
@@ -0,0 +1,7 @@
+#
+# Beancounters (BC)
+#
+# Copyright (C) 2006 OpenVZ. SWsoft Inc
+#
+
+obj-$(CONFIG_BEANCOUNTERS) += beancounter.o
--- /dev/null 2006-07-18 14:52:43.075228448 +0400
+++ ./kernel/bc/beancounter.c 2006-08-28 12:49:07.000000000 +0400
@@ -0,0 +1,256 @@
+/*
+ * kernel/bc/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 <linux/hash.h>
+
+#include <bc/beancounter.h>
+
+static kmem_cache_t *bc_cachep;
+static struct beancounter default_beancounter;
+
+static void init_beancounter_struct(struct beancounter *bc, bcid_t id);
+
+struct beancounter init_bc;
+
+const char *bc_rnames[] = {
+};
+
+static struct hlist_head bc_hash[BC_HASH_SIZE];
+static spinlock_t bc_hash_lock;
+#define bc_hash_fn(bcid) (hash_long(bcid, BC_HASH_BITS))
+
+/*
+ * Per resource beancounting. Resources are tied to their bc id.
+ * 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 beancounter *beancounter_findcreate(bcid_t id, int mask)
+{
+ struct beancounter *new_bc, *bc;
+ unsigned long flags;
+ struct hlist_head *slot;
+ struct hlist_node *pos;
+
+ slot = &bc_hash[bc_hash_fn(id)];
+ new_bc = NULL;
+
+retry:
+ spin_lock_irqsave(&bc_hash_lock, flags);
+ hlist_for_each_entry (bc, pos, slot, hash)
+ if (bc->bc_id == id)
+ break;
+
+ if (pos != NULL) {
+ get_beancounter(bc);
+ spin_unlock_irqrestore(&bc_hash_lock, flags);
+
+ if (new_bc != NULL)
+ kmem_cache_free(bc_cachep, new_bc);
+ return bc;
+ }
+
+ if (new_bc != NULL)
+ goto out_install;
+
+ spin_unlock_irqrestore(&bc_hash_lock, flags);
+
+ if (!(mask & BC_ALLOC))
+ goto out;
+
+ new_bc = kmem_cache_alloc(bc_cachep,
+ mask & BC_ALLOC_ATOMIC ? GFP_ATOMIC : GFP_KERNEL);
+ if (new_bc == NULL)
+ goto out;
+
+ *new_bc = default_beancounter;
+ init_beancounter_struct(new_bc, id);
+ goto retry;
+
+out_install:
+ hlist_add_head(&new_bc->hash, slot);
+ spin_unlock_irqrestore(&bc_hash_lock, flags);
+out:
+ return new_bc;
+}
+
+void put_beancounter(struct beancounter *bc)
+{
+ int i;
+ unsigned long flags;
+
+ if (!atomic_dec_and_lock_irqsave(&bc->bc_refcount,
+ &bc_hash_lock, flags))
+ return;
+
+ BUG_ON(bc == &init_bc);
+
+ for (i = 0; i < BC_RESOURCES; i++)
+ if (bc->bc_parms[i].held != 0)
+ printk("BC: %d has %lu of %s held on put", bc->bc_id,
+ bc->bc_parms[i].held, bc_rnames[i]);
+
+ hlist_del(&bc->hash);
+ spin_unlock_irqrestore(&bc_hash_lock, flags);
+
+ kmem_cache_free(bc_cachep, bc);
+}
+
+EXPORT_SYMBOL(put_beancounter);
+
+/*
+ * Generic resource charging stuff
+ */
+
+/* called with bc->bc_lock held and interrupts disabled */
+int bc_charge_locked(struct beancounter *bc, int resource, unsigned long val,
+ enum bc_severity strict)
+{
+ /*
+ * bc_value <= BC_MAXVALUE, value <= BC_MAXVALUE, and only one addition
+ * at the moment is possible so an overflow is impossible.
+ */
+ bc->bc_parms[resource].held += val;
+
+ switch (strict) {
+ case BC_BARRIER:
+ if (bc->bc_parms[resource].held >
+ bc->bc_parms[resource].barrier)
+ break;
+ /* fallthrough */
+ case BC_LIMIT:
+ if (bc->bc_parms[resource].held >
+ bc->bc_parms[resource].limit)
+ break;
+ /* fallthrough */
+ case BC_FORCE:
+ bc_adjust_held_minmax(bc, resource);
+ return 0;
+ default:
+ BUG();
+ }
+
+ bc->bc_parms[resource].failcnt++;
+ bc->bc_parms[resource].held -= val;
+ return -ENOMEM;
+}
+EXPORT_SYMBOL(bc_charge_locked);
+
+int bc_charge(struct beancounter *bc, int resource, unsigned long val,
+ enum bc_severity strict)
+{
+ int retval;
+ unsigned long flags;
+
+ BUG_ON(val > BC_MAXVALUE);
+
+ spin_lock_irqsave(&bc->bc_lock, flags);
+ retval = bc_charge_locked(bc, resource, val, strict);
+ spin_unlock_irqrestore(&bc->bc_lock, flags);
+ return retval;
+}
+EXPORT_SYMBOL(bc_charge);
+
+/* called with bc->bc_lock held and interrupts disabled */
+void bc_uncharge_locked(struct beancounter *bc, int resource, unsigned long val)
+{
+ if (unlikely(bc->bc_parms[resource].held < val)) {
+ printk("BC: overuncharging bc %d %s: val %lu, holds %lu\n",
+ bc->bc_id, bc_rnames[resource], val,
+ bc->bc_parms[resource].held);
+ val = bc->bc_parms[resource].held;
+ }
+
+ bc->bc_parms[resource].held -= val;
+ bc_adjust_held_minmax(bc, resource);
+}
+EXPORT_SYMBOL(bc_uncharge_locked);
+
+void bc_uncharge(struct beancounter *bc, int resource, unsigned long val)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&bc->bc_lock, flags);
+ bc_uncharge_locked(bc, resource, val);
+ spin_unlock_irqrestore(&bc->bc_lock, flags);
+}
+EXPORT_SYMBOL(bc_uncharge);
+
+/*
+ * Initialization
+ *
+ * struct 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 beancounter *bc, bcid_t id)
+{
+ atomic_set(&bc->bc_refcount, 1);
+ spin_lock_init(&bc->bc_lock);
+ bc->bc_id = id;
+}
+
+static void init_beancounter_nolimits(struct beancounter *bc)
+{
+ int k;
+
+ for (k = 0; k < BC_RESOURCES; k++) {
+ bc->bc_parms[k].limit = BC_MAXVALUE;
+ bc->bc_parms[k].barrier = BC_MAXVALUE;
+ }
+}
+
+static void init_beancounter_syslimits(struct beancounter *bc)
+{
+ int k;
+
+ for (k = 0; k < BC_RESOURCES; k++)
+ bc->bc_parms[k].barrier = bc->bc_parms[k].limit;
+}
+
+void __init bc_init_early(void)
+{
+ struct beancounter *bc;
+ struct hlist_head *slot;
+
+ bc = &init_bc;
+
+ init_beancounter_nolimits(bc);
+ init_beancounter_struct(bc, 0);
+
+ spin_lock_init(&bc_hash_lock);
+ slot = &bc_hash[bc_hash_fn(bc->bc_id)];
+ hlist_add_head(&bc->hash, slot);
+}
+
+void __init bc_init_late(void)
+{
+ struct beancounter *bc;
+
+ bc_cachep = kmem_cache_create("beancounters",
+ sizeof(struct beancounter),
+ 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC,
+ NULL, NULL);
+
+ bc = &default_beancounter;
+ init_beancounter_syslimits(bc);
+ init_beancounter_struct(bc, 0);
+}
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