Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=baf8f0f82dd79e374bf6fa9e996393df2bae3c21
Commit: baf8f0f82dd79e374bf6fa9e996393df2bae3c21
Parent: a05f7b15deb2903d9f0b5df33ddd4d186d5ecac1
Author: Pavel Emelianov <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 18 23:39:48 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Fri Oct 19 11:53:37 2007 -0700
pid namespaces: dynamic kmem cache allocator for pid namespaces
Add kmem_cache to pid_namespace to allocate pids from.
Since both implementations expand the struct pid to carry more numerical
values each namespace should have separate cache to store pids of different
sizes.
Each kmem cache is name "pid_<NR>", where <NR> is the number of numerical
ids
on the pid. Different namespaces with same level of nesting will have same
caches.
This patch has two FIXMEs that are to be fixed after we reach the consensus
about the struct pid itself.
The first one is that the namespace to free the pid from in free_pid() must
be
taken from pid. Now the init_pid_ns is used.
The second FIXME is about the cache allocation. When we do know how long
the
object will be then we'll have to calculate this size in create_pid_cachep.
Right now the sizeof(struct pid) value is used.
[EMAIL PROTECTED]: coding-style repair]
Signed-off-by: Pavel Emelianov <[EMAIL PROTECTED]>
Acked-by: Cedric Le Goater <[EMAIL PROTECTED]>
Acked-by: Sukadev Bhattiprolu <[EMAIL PROTECTED]>
Cc: Kirill Korotaev <[EMAIL PROTECTED]>
Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
Cc: Herbert Poetzl <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
include/linux/pid_namespace.h | 1 +
kernel/pid.c | 70 +++++++++++++++++++++++++++++++++++++---
2 files changed, 65 insertions(+), 6 deletions(-)
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index ddb9a4c..c471c0c 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -20,6 +20,7 @@ struct pid_namespace {
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
struct task_struct *child_reaper;
+ struct kmem_cache *pid_cachep;
};
extern struct pid_namespace init_pid_ns;
diff --git a/kernel/pid.c b/kernel/pid.c
index c6e3f9f..42de9af 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -32,7 +32,6 @@
#define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift)
static struct hlist_head *pid_hash;
static int pidhash_shift;
-static struct kmem_cache *pid_cachep;
struct pid init_struct_pid = INIT_STRUCT_PID;
int pid_max = PID_MAX_DEFAULT;
@@ -176,11 +175,16 @@ static int next_pidmap(struct pid_namespace *pid_ns, int
last)
fastcall void put_pid(struct pid *pid)
{
+ struct pid_namespace *ns;
+
if (!pid)
return;
+
+ /* FIXME - this must be the namespace this pid lives in */
+ ns = &init_pid_ns;
if ((atomic_read(&pid->count) == 1) ||
atomic_dec_and_test(&pid->count))
- kmem_cache_free(pid_cachep, pid);
+ kmem_cache_free(ns->pid_cachep, pid);
}
EXPORT_SYMBOL_GPL(put_pid);
@@ -208,12 +212,14 @@ struct pid *alloc_pid(void)
struct pid *pid;
enum pid_type type;
int nr = -1;
+ struct pid_namespace *ns;
- pid = kmem_cache_alloc(pid_cachep, GFP_KERNEL);
+ ns = current->nsproxy->pid_ns;
+ pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL);
if (!pid)
goto out;
- nr = alloc_pidmap(current->nsproxy->pid_ns);
+ nr = alloc_pidmap(ns);
if (nr < 0)
goto out_free;
@@ -230,7 +236,7 @@ out:
return pid;
out_free:
- kmem_cache_free(pid_cachep, pid);
+ kmem_cache_free(ns->pid_cachep, pid);
pid = NULL;
goto out;
}
@@ -365,6 +371,56 @@ struct pid *find_ge_pid(int nr)
}
EXPORT_SYMBOL_GPL(find_get_pid);
+struct pid_cache {
+ int nr_ids;
+ char name[16];
+ struct kmem_cache *cachep;
+ struct list_head list;
+};
+
+static LIST_HEAD(pid_caches_lh);
+static DEFINE_MUTEX(pid_caches_mutex);
+
+/*
+ * creates the kmem cache to allocate pids from.
+ * @nr_ids: the number of numerical ids this pid will have to carry
+ */
+
+static struct kmem_cache *create_pid_cachep(int nr_ids)
+{
+ struct pid_cache *pcache;
+ struct kmem_cache *cachep;
+
+ mutex_lock(&pid_caches_mutex);
+ list_for_each_entry (pcache, &pid_caches_lh, list)
+ if (pcache->nr_ids == nr_ids)
+ goto out;
+
+ pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL);
+ if (pcache == NULL)
+ goto err_alloc;
+
+ snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids);
+ cachep = kmem_cache_create(pcache->name,
+ /* FIXME add numerical ids here */
+ sizeof(struct pid), 0, SLAB_HWCACHE_ALIGN, NULL);
+ if (cachep == NULL)
+ goto err_cachep;
+
+ pcache->nr_ids = nr_ids;
+ pcache->cachep = cachep;
+ list_add(&pcache->list, &pid_caches_lh);
+out:
+ mutex_unlock(&pid_caches_mutex);
+ return pcache->cachep;
+
+err_cachep:
+ kfree(pcache);
+err_alloc:
+ mutex_unlock(&pid_caches_mutex);
+ return NULL;
+}
+
struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace
*old_ns)
{
BUG_ON(!old_ns);
@@ -412,5 +468,7 @@ void __init pidmap_init(void)
set_bit(0, init_pid_ns.pidmap[0].page);
atomic_dec(&init_pid_ns.pidmap[0].nr_free);
- pid_cachep = KMEM_CACHE(pid, SLAB_PANIC);
+ init_pid_ns.pid_cachep = create_pid_cachep(1);
+ if (init_pid_ns.pid_cachep == NULL)
+ panic("Can't create pid_1 cachep\n");
}
-
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