[PATCH 4/16] Change data structures for pid namespaces

Pavel Emelianov
2007-07-06T08:07:00Z

struct pid_namespace will have the kmem_cache to allocate
the pids from, the parent, as they are hierarchical, and
the level of nesting value.

struct pid will have a variable length array of pid_number-s
one for each namespace this pid lives in. The level value
shows the level of the namespace this pid lives in and thus -
the number of elements in the numbers array.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

include/linux/init_task.h | 6 ++++++
include/linux/pid.h | 9 +++++++++
include/linux/pid_namespace.h | 3 +++
kernel/pid.c | 3 ++-
4 files changed, 20 insertions(+), 1 deletion(-)

diff -upr linux-2.6.22-rc4-mm2.orig/include/linux/pid.h linux-2.6.22-rc4-mm2-2/include/linux/pid.h
--- linux-2.6.22-rc4-mm2.orig/include/linux/pid.h 2007-06-14 12:14:29.000000000 +0400
+++ linux-2.6.22-rc4-mm2-2/include/linux/pid.h 2007-07-04 19:00:38.000000000 +0400
@@ -40,6 +40,13 @@ enum pid_type
* processes.
*/

+struct pid_number {
+ /* Try to keep pid_chain in the same cacheline as nr for find_pid */
+ int nr;
+ struct pid_namespace *ns;
+ struct hlist_node pid_chain;
+};
+
struct pid
{
atomic_t count;
@@ -40,6 +40,8 @@ enum pid_type
/* lists of tasks that use this pid */
struct hlist_head tasks[PIDTYPE_MAX];
struct rcu_head rcu;
+ int level;
+ struct pid_number numbers[1];
};

extern struct pid init_struct_pid;
diff -upr linux-2.6.22-rc4-mm2.orig/include/linux/pid_namespace.h linux-2.6.22-rc4-mm2-2/include/linux/pid_namespace.h
--- linux-2.6.22-rc4-mm2.orig/include/linux/pid_namespace.h 2007-06-14 12:14:29.000000000 +0400
+++ linux-2.6.22-rc4-mm2-2/include/linux/pid_namespace.h 2007-07-04 19:00:39.000000000 +0400
@@ -16,7 +15,10 @@ struct pidmap {
struct kref kref;
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
+ int level;
struct task_struct *child_reaper;
+ struct kmem_cache *pid_cachep;
+ struct pid_namespace *parent;
};

extern struct pid_namespace init_pid_ns;
diff -upr linux-2.6.22-rc4-mm2.orig/include/linux/init_task.h linux-2.6.22-rc4-mm2-2/include/linux/init_task.h
--- linux-2.6.22-rc4-mm2.orig/include/linux/init_task.h 2007-06-14 12:14:29.000000000 +0400
+++ linux-2.6.22-rc4-mm2-2/include/linux/init_task.h 2007-07-04 19:00:38.000000000 +0400
@@ -91,6 +91,12 @@ extern struct group_info init_groups;
{ .first = &init_task.pids[PIDTYPE_SID].node }, \
}, \
.rcu = RCU_HEAD_INIT, \
+ .level = 0, \
+ .numbers = { { \
+ .nr = 0, \
+ .ns = &init_pid_ns, \
+ .pid_chain = { .next = NULL, .pprev = NULL }, \
+ }, } \
}

#define INIT_PID_LINK(type) \
diff -upr linux-2.6.22-rc4-mm2.orig/kernel/pid.c linux-2.6.22-rc4-mm2-2/kernel/pid.c
--- linux-2.6.22-rc4-mm2.orig/kernel/pid.c 2007-06-14 12:14:29.000000000 +0400
+++ linux-2.6.22-rc4-mm2-2/kernel/pid.c 2007-07-04 19:00:38.000000000 +0400
@@ -61,7 +62,8 @@ static inline int mk_pid(struct pid_name
[ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL }
},
.last_pid = 0,
- .child_reaper = &init_task
+ .level = 0,
+ .child_reaper = &init_task,
};

EXPORT_SYMBOL_GPL(init_pid_ns);