From: Cedric Le Goater <[EMAIL PROTECTED]>
Subject: [RFC][PATCH 3/6] pid namespace : use struct pid_nr
Allocate and attach a struct pid nr to the struct pid. When freeing the
pid, free the attached struct pid nrs.
Changelog:
- [Serge Hallyn's comment]: Add comments on what pid->lock protects
and that pid->nr will eventually go away.
Signed-off-by: Cedric Le Goater <[EMAIL PROTECTED]>
Signed-off-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
---
include/linux/pid.h | 3 +++
kernel/pid.c | 44 +++++++++++++++++++++++++++++++++++---------
2 files changed, 38 insertions(+), 9 deletions(-)
Index: lx26-20-mm2b/include/linux/pid.h
===================================================================
--- lx26-20-mm2b.orig/include/linux/pid.h 2007-03-09 15:29:21.000000000
-0800
+++ lx26-20-mm2b/include/linux/pid.h 2007-03-09 15:49:29.000000000 -0800
@@ -66,6 +66,9 @@ struct pid
/* lists of tasks that use this pid */
struct hlist_head tasks[PIDTYPE_MAX];
struct rcu_head rcu;
+ struct hlist_head pid_nrs;
+ spinlock_t lock;
+ /* protects pid_nrs list */
};
extern struct pid init_struct_pid;
Index: lx26-20-mm2b/kernel/pid.c
===================================================================
--- lx26-20-mm2b.orig/kernel/pid.c 2007-03-09 15:29:21.000000000 -0800
+++ lx26-20-mm2b/kernel/pid.c 2007-03-09 15:29:23.000000000 -0800
@@ -180,8 +180,19 @@ fastcall void put_pid(struct pid *pid)
if (!pid)
return;
if ((atomic_read(&pid->count) == 1) ||
- atomic_dec_and_test(&pid->count))
+ atomic_dec_and_test(&pid->count)) {
+ struct pid_nr* pid_nr;
+ struct hlist_node *pos, *next;
+
+ /*
+ * rcu is not needed anymore
+ */
+ hlist_for_each_entry_safe(pid_nr, pos, next, &pid->pid_nrs,
node) {
+ hlist_del_init(&pid_nr->node);
+ free_pid_nr(pid_nr);
+ }
kmem_cache_free(pid_cachep, pid);
+ }
}
EXPORT_SYMBOL_GPL(put_pid);
@@ -202,6 +213,9 @@ void free_pid_nr(struct pid_nr *pid_nr)
fastcall void free_pid(struct pid *pid)
{
+ struct pid_nr* pid_nr;
+ struct hlist_node *pos;
+
/* We can be called with write_lock_irq(&tasklist_lock) held */
unsigned long flags;
@@ -209,7 +223,8 @@ fastcall void free_pid(struct pid *pid)
hlist_del_rcu(&pid->pid_chain);
spin_unlock_irqrestore(&pidmap_lock, flags);
- free_pidmap(&init_pid_ns, pid->nr);
+ hlist_for_each_entry(pid_nr, pos, &pid->pid_nrs, node)
+ free_pidmap(pid_nr->pid_ns, pid_nr->nr);
call_rcu(&pid->rcu, delayed_put_pid);
}
@@ -290,31 +305,42 @@ struct pid *alloc_pid(void)
struct pid *pid;
enum pid_type type;
int nr = -1;
+ struct pid_nr *pid_nr;
pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
if (!pid)
- goto out;
+ return NULL;
nr = alloc_pidmap(task_pid_ns(current));
if (nr < 0)
- goto out_free;
+ goto out_free_pid;
+
+ pid_nr = alloc_pid_nr(task_pid_ns(current));
+ if (!pid_nr)
+ goto out_free_pidmap;
atomic_set(&pid->count, 1);
- pid->nr = nr;
+ pid->nr = pid_nr->nr = nr; /* pid->nr to be removed soon */
for (type = 0; type < PIDTYPE_MAX; ++type)
INIT_HLIST_HEAD(&pid->tasks[type]);
+ spin_lock_init(&pid->lock);
+
+ INIT_HLIST_HEAD(&pid->pid_nrs);
+ hlist_add_head_rcu(&pid_nr->node, &pid->pid_nrs);
+
spin_lock_irq(&pidmap_lock);
hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]);
spin_unlock_irq(&pidmap_lock);
-out:
return pid;
-out_free:
+out_free_pidmap:
+ free_pidmap(task_pid_ns(current), nr);
+
+out_free_pid:
kmem_cache_free(pid_cachep, pid);
- pid = NULL;
- goto out;
+ return NULL;
}
struct pid * fastcall find_pid(int nr)
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