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SubjectRe: [RFC][PATCH 1/5] Virtualization/containers: startup
From
Date
 On Fri, 2006-02-03 at 09:49 -0800, Linus Torvalds wrote:
> One thing I don't particularly like is some of the naming. To me "vps"
> doesn't sound particularly generic or logical. I realize that it probably
> makes perfect sense to you (and I assume it just means "virtual private
> servers"), but especially if you see patches 1-3 to really be independent
> of any "actual" virtualization code that is totally generic, I'd actually
> prefer a less specialized name.

I just did a global s/vps/container/ and it looks pretty reasonable, at
least from my point of view.

Couple of minor naming nitpick questions, though. Is vps/container_info
really what we want to call it? It seems to me to be the basis for a
real "container", without the _info part.

"tsk->owner_container" That makes it sound like a pointer to the "task
owner's container". How about "owning_container"? The "container
owning this task". Or, maybe just "container"?

Any particular reason for the "u32 id" in the vps_info struct as opposed
to one of the more generic types? Do we want to abstract this one in
the same way we do pid_t?

The "host" in "host_container_info" doesn't mean much to me. Though, I
guess it has some context in the UML space. Would "init_container_info"
or "root_container_info" be more descriptive?

Lastly, is this a place for krefs? I don't see a real need for a
destructor yet, but the idea is fresh in my mind.

How does the attached patch look?

-- Dave

memhotplug-dave/include/linux/container.h | 40 +++++++++++++++++++++++++
memhotplug-dave/include/linux/init_task.h | 2 +
memhotplug-dave/include/linux/sched.h | 4 ++
memhotplug-dave/init/main.c | 8 +++++
memhotplug-dave/kernel/exit.c | 2 +
memhotplug-dave/kernel/fork.c | 2 +
6 files changed, 58 insertions(+)
diff -puN include/linux/container.h~container-base include/linux/container.h
--- memhotplug/include/linux/container.h~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/include/linux/container.h 2006-02-03 10:21:36.000000000 -0800
@@ -0,0 +1,40 @@
+#ifndef __LINUX_VPS_INFO_H_
+#define __LINUX_VPS_INFO_H_
+
+#include <asm/types.h>
+#include <asm/atomic.h>
+
+struct task_struct;
+
+struct container {
+ u32 id;
+ struct task_struct *init_task;
+ atomic_t refcnt;
+};
+
+extern struct container root_container;
+
+static inline container_t get_container(container_t container)
+{
+ atomic_inc(&container->refcnt);
+ return container;
+}
+
+static inline void put_container(container_t container)
+{
+ atomic_dec(&container->refcnt);
+}
+
+#include <linux/sched.h>
+#include <asm/current.h>
+
+static inline container_t set_current_container(container_t container)
+{
+ container_t ret;
+
+ ret = current->owning_container;
+ current->owning_container = container;
+ return ret;
+}
+
+#endif
diff -puN include/linux/init_task.h~container-base include/linux/init_task.h
--- memhotplug/include/linux/init_task.h~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/include/linux/init_task.h 2006-02-03 10:23:49.000000000 -0800
@@ -3,6 +3,7 @@

#include <linux/file.h>
#include <linux/rcupdate.h>
+#include <linux/container.h>

#define INIT_FDTABLE \
{ \
@@ -121,6 +122,7 @@ extern struct group_info init_groups;
.journal_info = NULL, \
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
+ .owning_container = &root_container, \
}


diff -puN include/linux/sched.h~container-base include/linux/sched.h
--- memhotplug/include/linux/sched.h~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/include/linux/sched.h 2006-02-03 10:21:36.000000000 -0800
@@ -687,6 +687,7 @@ static inline void prefetch_stack(struct

struct audit_context; /* See audit.c */
struct mempolicy;
+struct container;

struct task_struct {
volatile long state; /* -1 unrunnable, 0 runnable, >0 stopped */
@@ -844,6 +845,7 @@ struct task_struct {
struct backing_dev_info *backing_dev_info;

struct io_context *io_context;
+ struct container *owning_container;

unsigned long ptrace_message;
siginfo_t *last_siginfo; /* For ptrace use. */
@@ -874,6 +876,8 @@ struct task_struct {
struct rcu_head rcu;
};

+#define current_container() (current->owning_container)
+
static inline pid_t process_group(struct task_struct *tsk)
{
return tsk->signal->pgrp;
diff -puN init/main.c~container-base init/main.c
--- memhotplug/init/main.c~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/init/main.c 2006-02-03 10:21:36.000000000 -0800
@@ -47,6 +47,7 @@
#include <linux/rmap.h>
#include <linux/mempolicy.h>
#include <linux/key.h>
+#include <linux/container.h>

#include <asm/io.h>
#include <asm/bugs.h>
@@ -434,6 +435,13 @@ void __init parse_early_param(void)
done = 1;
}

+struct container root_container = {
+ .id = 0,
+ .init_task = &init_task,
+ .refcnt = ATOMIC_INIT(1),
+};
+
+EXPORT_SYMBOL(root_container);
/*
* Activate the first processor.
*/
diff -puN kernel/exit.c~container-base kernel/exit.c
--- memhotplug/kernel/exit.c~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/kernel/exit.c 2006-02-03 10:21:36.000000000 -0800
@@ -31,6 +31,7 @@
#include <linux/signal.h>
#include <linux/cn_proc.h>
#include <linux/mutex.h>
+#include <linux/container.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -107,6 +108,7 @@ repeat:
spin_unlock(&p->proc_lock);
proc_pid_flush(proc_dentry);
release_thread(p);
+ put_container(p->owning_container);
put_task_struct(p);

p = leader;
diff -puN kernel/fork.c~container-base kernel/fork.c
--- memhotplug/kernel/fork.c~container-base 2006-02-03 10:21:36.000000000 -0800
+++ memhotplug-dave/kernel/fork.c 2006-02-03 10:21:36.000000000 -0800
@@ -44,6 +44,7 @@
#include <linux/rmap.h>
#include <linux/acct.h>
#include <linux/cn_proc.h>
+#include <linux/container.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -1132,6 +1133,7 @@ static task_t *copy_process(unsigned lon
p->ioprio = current->ioprio;

SET_LINKS(p);
+ get_container(p->owning_container);
if (unlikely(p->ptrace & PT_PTRACED))
__ptrace_link(p, current->parent);

_

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