Re: [PATCH] Process Aggregates (PAGG) update for 2.6.6
From: Erik Jacobson
Date: Fri May 28 2004 - 14:24:23 EST
> Looks nice to me. Can you fix up the comments a little to use kernel-doc
I just did this. Hopefully it looks ok?
> And after all that we have a nice hookin mechanism without users, so where
> are the modules layering ontop of pagg hiding? ;-)
We'll post the job patch shortly. Inescapable jobs makes use of PAGG.
New patch attached.
Thanks for the suggestions.
--
Erik Jacobson - Linux System Software - Silicon Graphics - Eagan, Minnesotadiff -Naru 2.6-patch/Documentation/pagg.txt 2.6pagg-patch/Documentation/pagg.txt
--- 2.6-patch/Documentation/pagg.txt 1969-12-31 18:00:00.000000000 -0600
+++ 2.6pagg-patch/Documentation/pagg.txt 2004-05-24 08:08:34.000000000 -0500
@@ -0,0 +1,32 @@
+Linux Process Aggregates (PAGG)
+-------------------------------
+
+The process aggregates infrastructure, or PAGG, provides a generalized
+mechanism for providing arbitrary process groups in Linux. PAGG consists
+of a series of functions for registering and unregistering support
+for new types of process aggregation containers with the kernel.
+This is similar to the support currently provided within Linux that
+allows for dynamic support of filesystems, block and character devices,
+symbol tables, network devices, serial devices, and execution domains.
+This implementation of PAGG provides developers the basic hooks necessary
+to implement kernel modules for specific process containers, such as
+the job container.
+
+The do_fork function in the kernel was altered to support PAGG. If a
+process is attached to any PAGG containers and subsequently forks a
+child process, the child process will also be attached to the same PAGG
+containers. The PAGG containers involved during the fork are notified
+that a new process has been attached. The notification is accomplished
+via a callback function provided by the PAGG module.
+
+The do_exit function in the kernel has also been altered. If a process
+is attached to any PAGG containers and that process is exiting, the PAGG
+containers are notified that a process has detached from the container.
+The notification is accomplished via a callback function provided by
+the PAGG module.
+
+The sys_execve function has been modified to support an optional callout
+that can be run when a process in a pagg list does an exec. It can be
+used, for example, by other kernel modules that wish to do advanced CPU
+placement on multi-processor systems (just one example).
+
diff -Naru 2.6-patch/fs/exec.c 2.6pagg-patch/fs/exec.c
--- 2.6-patch/fs/exec.c 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/fs/exec.c 2004-05-20 14:46:49.000000000 -0500
@@ -46,7 +46,7 @@
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/rmap.h>
-
+#include <linux/pagg.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/mmu_context.h>
@@ -1142,6 +1142,7 @@
retval = search_binary_handler(&bprm,regs);
if (retval >= 0) {
free_arg_pages(&bprm);
+ pagg_exec(current);
/* execve success */
security_bprm_free(&bprm);
diff -Naru 2.6-patch/include/linux/init_task.h 2.6pagg-patch/include/linux/init_task.h
--- 2.6-patch/include/linux/init_task.h 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/include/linux/init_task.h 2004-05-20 14:46:49.000000000 -0500
@@ -2,6 +2,7 @@
#define _LINUX__INIT_TASK_H
#include <linux/file.h>
+#include <linux/pagg.h>
#define INIT_FILES \
{ \
@@ -112,6 +113,7 @@
.proc_lock = SPIN_LOCK_UNLOCKED, \
.switch_lock = SPIN_LOCK_UNLOCKED, \
.journal_info = NULL, \
+ INIT_TASK_PAGG(tsk) \
}
diff -Naru 2.6-patch/include/linux/pagg.h 2.6pagg-patch/include/linux/pagg.h
--- 2.6-patch/include/linux/pagg.h 1969-12-31 18:00:00.000000000 -0600
+++ 2.6pagg-patch/include/linux/pagg.h 2004-05-28 13:56:52.000000000 -0500
@@ -0,0 +1,196 @@
+/*
+ * PAGG (Process Aggregates) interface
+ *
+ *
+ * Copyright (c) 2000-2002, 2004 Silicon Graphics, Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ *
+ * Contact information: Silicon Graphics, Inc., 1500 Crittenden Lane,
+ * Mountain View, CA 94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/NoticeExplan
+ */
+
+/*
+ * Data structure definitions and function prototypes used to implement
+ * process aggregates (paggs).
+ *
+ * Paggs provides a generalized way to implement process groupings or
+ * containers. Modules use these functions to register with the kernel as
+ * providers of process aggregation containers. The pagg data structures
+ * define the callback functions and data access pointers back into the
+ * pagg modules.
+ */
+
+#ifndef _LINUX_PAGG_H
+#define _LINUX_PAGG_H
+
+#include <linux/sched.h>
+
+#ifdef CONFIG_PAGG
+
+#define PAGG_NAMELN 32 /* Max chars in PAGG module name */
+
+
+/* Macro used to initialize a pagg_list structure after declaration
+ *
+ * Macro arguments:
+ * l: Task struct to init the pagg_list and semaphore in
+ */
+#define INIT_PAGG_LIST(_l) \
+do { \
+ INIT_LIST_HEAD(&(_l)->pagg_list); \
+ init_rwsem(&(_l)->pagg_sem); \
+} while(0)
+
+
+/*
+ * Used by task_struct to manage list of pagg attachments for the process.
+ * Each pagg provides the link between the process and the
+ * correct pagg container.
+ *
+ * STRUCT MEMBERS:
+ * hook: Reference to pagg module structure. That struct
+ * holds the name key and function pointers.
+ * data: Opaque data pointer - defined by pagg modules.
+ * entry: List pointers
+ */
+struct pagg {
+ struct pagg_hook *hook;
+ void *data;
+ struct list_head entry;
+};
+
+/*
+ * Used by pagg modules to define the callback functions into the
+ * module.
+ *
+ * STRUCT MEMBERS:
+ * name: The name of the pagg container type provided by
+ * the module. This will be set by the pagg module.
+ * attach: Function pointer to function used when attaching
+ * a process to the pagg container referenced by
+ * this struct.
+ * detach: Function pointer to function used when detaching
+ * a process to the pagg container referenced by
+ * this struct.
+ * init: Function pointer to initialization function. This
+ * function is used when the module is loaded to attach
+ * existing processes to a default container as defined by
+ * the pagg module. This is optional and may be set to
+ * NULL if it is not needed by the pagg module.
+ * data: Opaque data pointer - defined by pagg modules.
+ * module: Pointer to kernel module struct. Used to increment &
+ * decrement the use count for the module.
+ * entry: List pointers
+ * exec: Function pointer to function used when a process
+ * in the pagg container exec's a new process. This
+ * is optional and may be set to NULL if it is not
+ * needed by the pagg module.
+ * refcnt: Keep track of user count of the pagg hook
+ */
+struct pagg_hook {
+ struct module *module;
+ char *name; /* Name Key - restricted to 32 characters */
+ void *data; /* Opaque module specific data */
+ struct list_head entry; /* List pointers */
+ atomic_t refcnt; /* usage counter */
+ int (*init)(struct task_struct *, struct pagg *);
+ int (*attach)(struct task_struct *, struct pagg *, void*);
+ int (*detach)(struct task_struct *, struct pagg *);
+ void (*exec)(struct task_struct *, struct pagg *);
+};
+
+
+/* Kernel service functions for providing PAGG support */
+extern struct pagg *pagg_get(struct task_struct *task, char *key);
+extern struct pagg *pagg_alloc(struct task_struct *task,
+ struct pagg_hook *pt);
+extern void pagg_free(struct pagg *pagg);
+extern int pagg_hook_register(struct pagg_hook *pt_new);
+extern int pagg_hook_unregister(struct pagg_hook *pt_old);
+extern int __pagg_attach(struct task_struct *to_task,
+ struct task_struct *from_task);
+extern int __pagg_detach(struct task_struct *task);
+extern int __pagg_exec(struct task_struct *task);
+
+/* function used when a child process must inherit attachment to pagg
+ * containers from the parent.
+ */
+static inline int pagg_attach(struct task_struct *child,
+ struct task_struct *parent)
+{
+ INIT_PAGG_LIST(child);
+ if (!list_empty(&parent->pagg_list))
+ return __pagg_attach(child, parent);
+ return 0;
+}
+
+
+/**
+ * pagg_detach - Detach a process from a pagg container it is a member of
+ * @task: The task the pagg will be detached from
+ *
+ */
+static inline void pagg_detach(struct task_struct *task)
+{
+ if (!list_empty(&task->pagg_list))
+ __pagg_detach(task);
+}
+
+/**
+ * pagg_exec - Used when a process exec's
+ * @task: The process doing the exec
+ *
+ */
+static inline void pagg_exec(struct task_struct *task)
+{
+ if (!list_empty(&task->pagg_list))
+ __pagg_exec(task);
+}
+
+/**
+ * INIT_TASK_PAGG - Used in INIT_TASK to set the head and sem of pagg_list
+ * @tsk: The task work with
+ *
+ * Marco Used in INIT_TASK to set the head and sem of pagg_list.
+ * If CONFIG_PAGG is off, it is defined as an empty macro below.
+ *
+ */
+#define INIT_TASK_PAGG(tsk) \
+ .pagg_list = LIST_HEAD_INIT(tsk.pagg_list), \
+ .pagg_sem = __RWSEM_INITIALIZER(tsk.pagg_sem)
+
+#else /* CONFIG_PAGG */
+
+/*
+ * Replacement macros used when PAGG (Process Aggregates) support is not
+ * compiled into the kernel.
+ */
+#define INIT_TASK_PAGG(tsk)
+#define INIT_PAGG_LIST(l) do { } while(0)
+#define pagg_attach(ct, pt) do { } while(0)
+#define pagg_detach(t) do { } while(0)
+#define pagg_exec(t) do { } while(0)
+
+#endif /* CONFIG_PAGG */
+
+#endif /* _LINUX_PAGG_H */
diff -Naru 2.6-patch/include/linux/sched.h 2.6pagg-patch/include/linux/sched.h
--- 2.6-patch/include/linux/sched.h 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/include/linux/sched.h 2004-05-26 08:31:24.000000000 -0500
@@ -499,11 +499,16 @@
struct dentry *proc_dentry;
struct backing_dev_info *backing_dev_info;
-
struct io_context *io_context;
unsigned long ptrace_message;
siginfo_t *last_siginfo; /* For ptrace use. */
+
+#ifdef CONFIG_PAGG
+/* List of pagg (process aggregate) attachments */
+ struct list_head pagg_list;
+ struct rw_semaphore pagg_sem;
+#endif
};
static inline pid_t process_group(struct task_struct *tsk)
diff -Naru 2.6-patch/init/Kconfig 2.6pagg-patch/init/Kconfig
--- 2.6-patch/init/Kconfig 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/init/Kconfig 2004-05-20 14:46:49.000000000 -0500
@@ -121,6 +121,14 @@
up to the user level program to do useful things with this
information. This is generally a good idea, so say Y.
+config PAGG
+ bool "Support for process aggregates (PAGGs)"
+ help
+ Say Y here if you will be loading modules which provide support
+ for process aggregate containers. Examples of such modules include the
+ Linux Jobs module and the Linux Array Sessions module. If you will not
+ be using such modules, say N.
+
config SYSCTL
bool "Sysctl support"
---help---
diff -Naru 2.6-patch/kernel/exit.c 2.6pagg-patch/kernel/exit.c
--- 2.6-patch/kernel/exit.c 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/kernel/exit.c 2004-05-20 14:46:49.000000000 -0500
@@ -22,7 +22,7 @@
#include <linux/profile.h>
#include <linux/mount.h>
#include <linux/proc_fs.h>
-
+#include <linux/pagg.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>
@@ -799,6 +799,9 @@
module_put(tsk->binfmt->module);
tsk->exit_code = code;
+
+ pagg_detach(tsk);
+
exit_notify(tsk);
schedule();
BUG();
diff -Naru 2.6-patch/kernel/fork.c 2.6pagg-patch/kernel/fork.c
--- 2.6-patch/kernel/fork.c 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/kernel/fork.c 2004-05-21 10:13:53.000000000 -0500
@@ -33,7 +33,7 @@
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/audit.h>
-
+#include <linux/pagg.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/uaccess.h>
@@ -236,6 +236,9 @@
init_task.rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
init_task.rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
+
+ /* Initialize the pagg list in pid 0 before it can clone itself. */
+ INIT_PAGG_LIST(current);
}
static struct task_struct *dup_task_struct(struct task_struct *orig)
@@ -995,6 +998,12 @@
p->parent_exec_id = p->self_exec_id;
+ /*
+ * call pagg modules to properly attach new process to the same
+ * process aggregate containers as the parent process.
+ */
+ pagg_attach(p, current);
+
/* ok, now we should be set up.. */
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
p->pdeath_signal = 0;
diff -Naru 2.6-patch/kernel/Makefile 2.6pagg-patch/kernel/Makefile
--- 2.6-patch/kernel/Makefile 2004-05-10 12:06:11.000000000 -0500
+++ 2.6pagg-patch/kernel/Makefile 2004-05-20 14:46:49.000000000 -0500
@@ -18,6 +18,7 @@
obj-$(CONFIG_PM) += power/
obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
obj-$(CONFIG_COMPAT) += compat.o
+obj-$(CONFIG_PAGG) += pagg.o
obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_IKCONFIG_PROC) += configs.o
obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
diff -Naru 2.6-patch/kernel/pagg.c 2.6pagg-patch/kernel/pagg.c
--- 2.6-patch/kernel/pagg.c 1969-12-31 18:00:00.000000000 -0600
+++ 2.6pagg-patch/kernel/pagg.c 2004-05-28 13:06:11.000000000 -0500
@@ -0,0 +1,380 @@
+/*
+ * PAGG (Process Aggregates) interface
+ *
+ *
+ * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Contact information: Silicon Graphics, Inc., 1500 Crittenden Lane,
+ * Mountain View, CA 94043, or:
+ *
+ * http://www.sgi.com
+ */
+
+#include <linux/config.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/pagg.h>
+#include <asm/semaphore.h>
+
+/* list of pagg hook entries that reference the "module" implementations */
+static LIST_HEAD(pagg_hook_list);
+static DECLARE_RWSEM(pagg_hook_list_sem);
+
+
+/**
+ * pagg_get - get a pagg given a search key
+ * @task: We examine the pagg_list from the given task
+ * @key: Key name of pagg we wish to retrieve
+ *
+ * Given a pagg_list list structure, this function will return
+ * a pointer to the pagg struct that matches the search
+ * key. If the key is not found, the function will return NULL.
+ *
+ * The caller should hold at least a read lock on the pagg_list
+ * for task using down_read(&task->pagg_list.sem).
+ *
+ */
+struct pagg *
+pagg_get(struct task_struct *task, char *key)
+{
+ struct pagg *pagg;
+
+ list_for_each_entry(pagg, &task->pagg_list, entry) {
+ if (!strcmp(pagg->hook->name,key))
+ return pagg;
+ }
+ return NULL;
+}
+
+
+/**
+ * pagg_alloc - Insert a new pagg in to the pagg_list for a task
+ * @task: Task we want to insert the pagg in to
+ * @pagg_hook: Pagg hook to associate with the new pagg
+ *
+ * Given a task and a pagg hook, this function will allocate
+ * a new pagg structure, initialize the settings, and insert the pagg into
+ * the pagg_list for the task.
+ *
+ * The caller for this function should hold at least a read lock on the
+ * pagg_hook_list_sem - or ensure that the pagg hook entry cannot be
+ * removed. If this function was called from the pagg module (usually the
+ * case), then the caller need not hold this lock. The caller should hold
+ * a write lock on for the tasks pagg_sem. This can be locked using
+ * down_write(&task->pagg_sem)
+ *
+ */
+struct pagg *
+pagg_alloc(struct task_struct *task, struct pagg_hook *pagg_hook)
+{
+ struct pagg *pagg;
+
+ pagg = kmalloc(sizeof(struct pagg), GFP_KERNEL);
+ if (!pagg)
+ return NULL;
+
+ pagg->hook = pagg_hook;
+ pagg->data = NULL;
+ atomic_inc(&pagg_hook->refcnt); /* Increase hook's reference count */
+ list_add_tail(&pagg->entry, &task->pagg_list);
+ return pagg;
+}
+
+
+/**
+ * pagg_free - Delete pagg from the list and free its memory
+ * @pagg: The pagg to free
+ *
+ * This function will ensure the pagg is deleted form
+ * the list of pagg entries for the task. Finally, the memory for the
+ * pagg is discarded.
+ *
+ * The caller of this function should hold a write lock on the pagg_sem
+ * for the task. This can be locked using down_write(&task->pagg_sem).
+ *
+ * Prior to calling pagg_free, the pagg should have been detached from the
+ * pagg container represented by this pagg. That is usually done using
+ * p->hook->detach(task, pagg);
+ *
+ */
+void
+pagg_free(struct pagg *pagg)
+{
+ atomic_dec(&pagg->hook->refcnt); /* decr the reference count on the hook */
+ list_del(&pagg->entry);
+ kfree(pagg);
+}
+
+
+/**
+ * get_pagg_hook - Get the pagg hook matching the requested name
+ * @key: The name of the pagg hook to get
+ *
+ * Given a pagg hook name key, this function will return a pointer
+ * to the pagg_hook struct that matches the name.
+ *
+ * You should hold either the write or read lock for pagg_hook_list_sem
+ * before using this function. This will ensure that the pagg_hook_list
+ * does not change while iterating through the list entries.
+ *
+ */
+static struct pagg_hook *
+get_pagg_hook(char *key)
+{
+ struct pagg_hook *pagg_hook;
+
+ list_for_each_entry(pagg_hook, &pagg_hook_list, entry) {
+ if (!strcmp(pagg_hook->name, key)) {
+ return pagg_hook;
+ }
+ }
+ return NULL;
+}
+
+
+/**
+ * pagg_hook_register - Register a new pagg hook and enter it the list
+ * @pagg_hook_new: The new pagg hook to register
+ *
+ * Used to register a new pagg hook and enter it into the pagg_hook_list.
+ * The service name for a pagg hook is restricted to 32 characters.
+ *
+ * In the future an initialization function may also be defined so that all
+ * existing tasks can be assigned to a default pagg entry for the hook.
+ * However, this would require iterating through the tasklist. To do that
+ * requires that the tasklist_lock be read locked. Since the initialization
+ * function might be in a module, and therefore it might sleep (implementors
+ * decision), holding the tasklist_lock seems like a bad idea. It may be a
+ * requirement that the initialization function will be strictly forbidden
+ * from locking - by gentlemans agreement...
+ *
+ * If a memory error is encountered, the pagg hook is unregistered and any
+ * tasks that have been attached to the initial pagg container are detached
+ * from that container.
+ *
+ */
+int
+pagg_hook_register(struct pagg_hook *pagg_hook_new)
+{
+ struct pagg_hook *pagg_hook = NULL;
+
+ /* ADD NEW PAGG MODULE TO ACCESS LIST */
+ if (!pagg_hook_new)
+ return -EINVAL; /* error */
+ if (!list_empty(&pagg_hook_new->entry))
+ return -EINVAL; /* error */
+ if (pagg_hook_new->name == NULL || strlen(pagg_hook_new->name) > PAGG_NAMELN)
+ return -EINVAL; /* error */
+
+ /* Try to insert new hook entry into the pagg hook list */
+ down_write(&pagg_hook_list_sem);
+
+ pagg_hook = get_pagg_hook(pagg_hook_new->name);
+
+ if (pagg_hook) {
+ up_write(&pagg_hook_list_sem);
+ printk(KERN_WARNING "Attempt to register duplicate"
+ " PAGG support (name=%s)\n", pagg_hook_new->name);
+ return -EBUSY;
+ }
+
+ /* Okay, we can insert into the pagg hook list */
+ list_add_tail(&pagg_hook_new->entry, &pagg_hook_list);
+ /* set the ref count to zero */
+ atomic_set(&pagg_hook_new->refcnt, 0);
+ /* printk("DEBUG - pagg hook register - refcnt now: %d\n",
+ atomic_read(&pagg_hook_new->refcnt)); */
+ up_write(&pagg_hook_list_sem);
+
+ printk(KERN_INFO "Registering PAGG support for (name=%s)\n",
+ pagg_hook_new->name);
+
+ return 0; /* success */
+
+}
+
+
+/**
+ * pagg_hook_unregister - Unregister pagg hook and remove it from the list
+ * @pagg_hook_old: The hook to unregister and remove
+ *
+ * Used to unregister pagg hooks and remove them from the pagg_hook_list.
+ * Once the pagg hook entry in the pagg_hook_list is found, we check if
+ * the pagg hook is still in use.
+ *
+ */
+int
+pagg_hook_unregister(struct pagg_hook *pagg_hook_old)
+{
+ struct pagg_hook *pagg_hook;
+
+ /* Check the validity of the arguments */
+ if (!pagg_hook_old)
+ return -EINVAL; /* error */
+ if (list_empty(&pagg_hook_old->entry))
+ return -EINVAL; /* error */
+ if (pagg_hook_old->name == NULL)
+ return -EINVAL; /* error */
+
+ down_write(&pagg_hook_list_sem);
+
+ pagg_hook = get_pagg_hook(pagg_hook_old->name);
+
+ /* printk("DEBUG - pagg hook unregister - refcnt now: %d\n",
+ * atomic_read(&pagg_hook->refcnt));
+ */
+
+ if (pagg_hook && pagg_hook == pagg_hook_old) {
+ /* Is the pagg hook busy? Check if the refcnt is zero */
+ if (atomic_read(&pagg_hook->refcnt) != 0) {
+ up_write(&pagg_hook_list_sem);
+ printk(KERN_INFO "Failed attempt to unregister a PAGG hook from: %s\n", pagg_hook_old->name);
+ return -EBUSY;
+ }
+ list_del_init(&pagg_hook->entry);
+ up_write(&pagg_hook_list_sem);
+
+ printk(KERN_INFO "Unregistering PAGG support for"
+ " (name=%s)\n", pagg_hook_old->name);
+
+ return 0; /* success */
+ }
+
+ up_write(&pagg_hook_list_sem);
+
+ printk(KERN_WARNING "Attempt to unregister PAGG support (name=%s)"
+ " failed - not found\n", pagg_hook_old->name);
+
+ return -EINVAL; /* error */
+}
+
+
+/**
+ * __pagg_attach - Attach a new task to the same containers of its parent
+ * @to_task: The child task that will inherit the parent's containers
+ * @from_task: The parent task
+ *
+ * Used to attach a new task to the same pagg containers to which it's parent
+ * is attached.
+ *
+ * The "from" argument is the parent task. The "to" argument is the child
+ * task.
+ *
+ */
+int __pagg_attach(struct task_struct *to_task, struct task_struct *from_task)
+{
+ int retcode = 0;
+ struct pagg *from_pagg;
+
+ /* lock the parents pagg_list we are copying from */
+ down_read(&from_task->pagg_sem); /* read lock the pagg list */
+
+ list_for_each_entry(from_pagg, &from_task->pagg_list, entry) {
+ struct pagg *to_pagg = NULL;
+
+ to_pagg = pagg_alloc(to_task, from_pagg->hook);
+ if (!to_pagg) {
+ retcode = -ENOMEM;
+ goto error_return;
+ }
+ retcode = to_pagg->hook->attach(to_task, to_pagg, from_pagg->data);
+ if (retcode != 0) {
+ /* attach should issue error message */
+ goto error_return;
+ }
+ }
+
+ up_read(&from_task->pagg_sem); /* unlock the pagg list */
+
+ return 0; /* success */
+
+ error_return:
+ /*
+ * Clean up all the pagg attachments made on behalf of the new
+ * task. Set new task pagg ptr to NULL for return.
+ */
+ up_read(&from_task->pagg_sem); /* unlock the pagg list */
+ __pagg_detach(to_task);
+ return retcode; /* failure */
+}
+
+/**
+ * __pagg_detach - Detach a task from all pagg containers it is attached to
+ * @task: Task to detach from pagg containers
+ *
+ * Used to detach a task from all pagg containers to which it is attached.
+ *
+ */
+int
+__pagg_detach(struct task_struct *task)
+{
+ struct pagg *pagg;
+ struct pagg *paggtmp;
+ int retcode = 0;
+ int rettmp = 0;
+
+ /* Remove ref. to paggs from task immediately */
+ down_write(&task->pagg_sem); /* write lock pagg list */
+
+ list_for_each_entry_safe(pagg, paggtmp, &task->pagg_list, entry) {
+ rettmp = pagg->hook->detach(task, pagg);
+ if (rettmp) {
+ /* an error message should be logged in free_pagg */
+ retcode = rettmp;
+ }
+ pagg_free(pagg);
+ }
+
+ up_write(&task->pagg_sem); /* write unlock the pagg list */
+
+ return retcode; /* 0 = success, else return last code for failure */
+}
+
+
+/**
+ * __pagg_exec - Execute callback when a process in a container execs
+ * @task: We go through the pagg list in the given task
+ *
+ * Used to when a process that is in a pagg container does an exec.
+ *
+ * The "from" argument is the task. The "name" argument is the name
+ * of the process being exec'ed.
+ *
+ */
+int __pagg_exec(struct task_struct *task)
+{
+ struct pagg *pagg;
+
+ /* lock the parents pagg_list we are copying from */
+ down_read(&task->pagg_sem); /* lock the pagg list */
+
+ list_for_each_entry(pagg, &task->pagg_list, entry) {
+ if (pagg->hook->exec) /* conditional because it's optional */
+ pagg->hook->exec(task, pagg);
+ }
+
+ up_read(&task->pagg_sem); /* unlock the pagg list */
+ return 0;
+}
+
+
+EXPORT_SYMBOL(pagg_get);
+EXPORT_SYMBOL(pagg_alloc);
+EXPORT_SYMBOL(pagg_free);
+EXPORT_SYMBOL(pagg_hook_register);
+EXPORT_SYMBOL(pagg_hook_unregister);