From: Erik Jacobson <erikj@subway.americas.sgi.com>
Signed-off-by: Erik Jacobson <erikj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/Documentation/pagg.txt | 32 ++
25-akpm/fs/exec.c | 2
25-akpm/include/linux/init_task.h | 2
25-akpm/include/linux/pagg.h | 202 ++++++++++++++++
25-akpm/include/linux/sched.h | 7
25-akpm/init/Kconfig | 8
25-akpm/kernel/Makefile | 1
25-akpm/kernel/fork.c | 12
25-akpm/kernel/pagg.c | 477 ++++++++++++++++++++++++++++++++++++++
9 files changed, 743 insertions(+)
diff -puN /dev/null Documentation/pagg.txt
--- /dev/null 2003-09-15 06:40:47.000000000 -0700
+++ 25-akpm/Documentation/pagg.txt 2004-08-15 22:48:33.575620128 -0700
@@ -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 -puN fs/exec.c~process-aggregates fs/exec.c
--- 25/fs/exec.c~process-aggregates 2004-08-15 22:48:33.565621648 -0700
+++ 25-akpm/fs/exec.c 2004-08-15 22:48:33.576619976 -0700
@@ -46,6 +46,7 @@
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/rmap.h>
+#include <linux/pagg.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
@@ -1158,6 +1159,7 @@ int do_execve(char * filename,
retval = search_binary_handler(&bprm,regs);
if (retval >= 0) {
free_arg_pages(&bprm);
+ pagg_exec(current);
/* execve success */
security_bprm_free(&bprm);
diff -puN include/linux/init_task.h~process-aggregates include/linux/init_task.h
--- 25/include/linux/init_task.h~process-aggregates 2004-08-15 22:48:33.566621496 -0700
+++ 25-akpm/include/linux/init_task.h 2004-08-15 22:48:33.577619824 -0700
@@ -2,6 +2,7 @@
#define _LINUX__INIT_TASK_H
#include <linux/file.h>
+#include <linux/pagg.h>
#define INIT_FILES \
{ \
@@ -112,6 +113,7 @@ extern struct group_info init_groups;
.proc_lock = SPIN_LOCK_UNLOCKED, \
.switch_lock = SPIN_LOCK_UNLOCKED, \
.journal_info = NULL, \
+ INIT_TASK_PAGG(tsk) \
}
diff -puN /dev/null include/linux/pagg.h
--- /dev/null 2003-09-15 06:40:47.000000000 -0700
+++ 25-akpm/include/linux/pagg.h 2004-08-15 22:48:33.578619672 -0700
@@ -0,0 +1,202 @@
+/*
+ * 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 */
+
+
+/**
+ * INIT_PAGG_LIST - used to initialize a pagg_list structure after declaration
+ * @_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*);
+ void (*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 void __pagg_attach(struct task_struct *to_task,
+ struct task_struct *from_task);
+extern void __pagg_detach(struct task_struct *task);
+extern int __pagg_exec(struct task_struct *task);
+
+/**
+ * pagg_attach - child inherits attachment to pagg containers of its parent
+ * @child: child task - to inherit
+ * @parent: parenet task - child inherits pagg containers from this parent
+ *
+ * function used when a child process must inherit attachment to pagg
+ * containers from the parent.
+ *
+ */
+static inline void pagg_attach(struct task_struct *child,
+ struct task_struct *parent)
+{
+ INIT_PAGG_LIST(child);
+ if (!list_empty(&parent->pagg_list))
+ __pagg_attach(child, parent);
+ return;
+}
+
+
+/**
+ * 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 -puN include/linux/sched.h~process-aggregates include/linux/sched.h
--- 25/include/linux/sched.h~process-aggregates 2004-08-15 22:48:33.568621192 -0700
+++ 25-akpm/include/linux/sched.h 2004-08-15 22:48:33.579619520 -0700
@@ -561,6 +561,13 @@ struct task_struct {
struct mempolicy *mempolicy;
short il_next; /* could be shared with used_math */
#endif
+
+#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 -puN init/Kconfig~process-aggregates init/Kconfig
--- 25/init/Kconfig~process-aggregates 2004-08-15 22:48:33.569621040 -0700
+++ 25-akpm/init/Kconfig 2004-08-15 22:48:33.580619368 -0700
@@ -123,6 +123,14 @@ config BSD_PROCESS_ACCT_V3
for processing it. A preliminary version of these tools is available
at <http://http://www.de.kernel.org/pub/linux/utils/acct/>.
+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 -puN kernel/fork.c~process-aggregates kernel/fork.c
--- 25/kernel/fork.c~process-aggregates 2004-08-15 22:48:33.570620888 -0700
+++ 25-akpm/kernel/fork.c 2004-08-15 22:48:33.581619216 -0700
@@ -36,6 +36,7 @@
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/rmap.h>
+#include <linux/pagg.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -87,6 +88,8 @@ void __put_task_struct(struct task_struc
WARN_ON(atomic_read(&tsk->usage));
WARN_ON(tsk == current);
+ pagg_detach(tsk);
+
if (unlikely(tsk->audit_context))
audit_free(tsk);
security_task_free(tsk);
@@ -236,6 +239,9 @@ void __init fork_init(unsigned long memp
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)
@@ -1022,6 +1028,12 @@ static task_t *copy_process(unsigned lon
sched_fork(p);
/*
+ * call pagg modules to properly attach new process to the same
+ * process aggregate containers as the parent process.
+ */
+ pagg_attach(p, current);
+
+ /*
* Ok, make it visible to the rest of the system.
* We dont wake it up yet.
*/
diff -puN kernel/Makefile~process-aggregates kernel/Makefile
--- 25/kernel/Makefile~process-aggregates 2004-08-15 22:48:33.572620584 -0700
+++ 25-akpm/kernel/Makefile 2004-08-15 22:48:33.581619216 -0700
@@ -19,6 +19,7 @@ obj-$(CONFIG_KALLSYMS) += kallsyms.o
obj-$(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 -puN /dev/null kernel/pagg.c
--- /dev/null 2003-09-15 06:40:47.000000000 -0700
+++ 25-akpm/kernel/pagg.c 2004-08-15 22:48:33.583618912 -0700
@@ -0,0 +1,477 @@
+/*
+ * 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;
+}
+
+/**
+ * remove_client_paggs_from_all_tasks - Remove all paggs associated with hook
+ * @php: Pagg hook associated with paggs to purge
+ *
+ * Given a pagg hook, this function will remove all paggs associated with that
+ * pagg hook from all tasks calling the provided function on each pagg.
+ *
+ * If there is a detach function associated with the pagg, it is called
+ * before the pagg is freed.
+ *
+ * This is meant to be used by pagg_hook_register and pagg_hook_unregister
+ *
+ */
+static void
+remove_client_paggs_from_all_tasks(struct pagg_hook *php)
+{
+ if (php == NULL)
+ return;
+
+ /* Because of internal race conditions we can't gaurantee
+ * getting every task in just one pass so we just keep going
+ * until there are no tasks with paggs from this hook attached.
+ * The inefficiency of this should be tempered by the fact that this
+ * happens at most once for each registered client.
+ */
+ while (atomic_read(&php->refcnt) != 0) {
+ struct task_struct *p = NULL;
+
+ read_lock(&tasklist_lock);
+ for_each_process(p) {
+ struct pagg *paggp;
+
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+ down_write(&p->pagg_sem);
+ paggp = pagg_get(p, php->name);
+ if (paggp != NULL) {
+ (void)php->detach(p, paggp);
+ pagg_free(paggp);
+ }
+ up_write(&p->pagg_sem);
+ read_lock(&tasklist_lock);
+
+ /* If a PAGG got removed from the list while we're going through
+ * each process, the tasks list for the process would be empty. In
+ * that case, break out of this for_each_process so we can do it
+ * again. */
+ if (list_empty(&p->tasks)) {
+ put_task_struct(p);
+ break;
+ } else
+ put_task_struct(p);
+
+ }
+ read_unlock(&tasklist_lock);
+ }
+}
+
+/**
+ * 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.
+ *
+ * If an "init()" function is supplied in the hook being registered then a
+ * pagg will be attached to all existing tasks and the supplied "init()"
+ * function will be applied to it. If any call to the supplied "init()"
+ * function returns a non zero result the registration will be aborted. As
+ * part of the abort process, all paggs belonging to the new client will be
+ * removed from all tasks and the supplied "detach()" function will be
+ * called on them.
+ *
+ * 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);
+
+ /* Now we can call the initializer function (if present) for each task */
+ if (pagg_hook_new->init != NULL) {
+ int init_result = 0;
+ int task_exited;
+
+ /* Because of internal race conditions we can't gaurantee
+ * getting every task in just one pass so we just keep going
+ * until we don't find any unitialized tasks. The inefficiency
+ * of this should be tempered by the fact that this happens
+ * at most once for each registered client.
+ */
+ do {
+ struct task_struct *p = NULL;
+
+ read_lock(&tasklist_lock);
+ for_each_process(p) {
+ struct pagg *paggp;
+
+ get_task_struct(p);
+ read_unlock(&tasklist_lock);
+ down_write(&p->pagg_sem);
+ paggp = pagg_get(p, pagg_hook_new->name);
+ if (paggp == NULL) {
+ paggp = pagg_alloc(p, pagg_hook_new);
+ if (paggp != NULL)
+ init_result = pagg_hook_new->init(p, paggp);
+ else
+ init_result = -ENOMEM;
+ }
+ up_write(&p->pagg_sem);
+ read_lock(&tasklist_lock);
+ /* Like in remove_client_paggs_from_all_tasks, if the task
+ * disappeared on us while we were going through the
+ * for_each_process loop, we need to start over with that loop.
+ * That's why we have the list_empty here */
+ task_exited = list_empty(&p->tasks);
+ put_task_struct(p);
+ if ((init_result != 0) || task_exited) {
+ break;
+ }
+ }
+ read_unlock(&tasklist_lock);
+ } while ((init_result == 0) && task_exited);
+
+ /*
+ * if anything went wrong during initialisation abandon the
+ * registration process
+ */
+ if (init_result != 0) {
+ remove_client_paggs_from_all_tasks(pagg_hook_new);
+ list_del_init(&pagg_hook_new->entry);
+ up_write(&pagg_hook_list_sem);
+
+ printk(KERN_WARNING "Registering PAGG support for"
+ " (name=%s) failed\n", pagg_hook_new->name);
+
+ return init_result; /* hook init function error result */
+ }
+ }
+
+ 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, paggs associated
+ * with the hook (if any) will have their detach function called and will
+ * be detached.
+ *
+ */
+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);
+
+ if (pagg_hook && pagg_hook == pagg_hook_old) {
+ remove_client_paggs_from_all_tasks(pagg_hook);
+ 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.
+ *
+ */
+void
+__pagg_attach(struct task_struct *to_task, struct task_struct *from_task)
+{
+ 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) {
+ goto error_return;
+ }
+ if (to_pagg->hook->attach(to_task, to_pagg, from_pagg->data) != 0 )
+ goto error_return;
+ }
+
+ up_read(&from_task->pagg_sem); /* unlock the pagg list */
+
+ return; /* 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; /* 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.
+ *
+ */
+void
+__pagg_detach(struct task_struct *task)
+{
+ struct pagg *pagg;
+ struct pagg *paggtmp;
+
+ /* 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) {
+ pagg->hook->detach(task, pagg);
+ pagg_free(pagg);
+ }
+
+ up_write(&task->pagg_sem); /* write unlock the pagg list */
+
+ return; /* 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);
_