Commit 1adfcb03 authored by Al Viro's avatar Al Viro
Browse files

pid_namespace: make freeing struct pid_namespace rcu-delayed 



makes procfs ->premission() instances safety in RCU mode independent
from vfsmount_lock.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1dcddd4a

include/linux/pid_namespace.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct bsd_acct_struct; 
struct pid_namespace {

	struct kref kref;

	struct pidmap pidmap[PIDMAP_ENTRIES];

	struct rcu_head rcu;

	int last_pid;

	unsigned int nr_hashed;

	struct task_struct *child_reaper;

kernel/pid_namespace.c

+7 −1
Original line number Diff line number Diff line
@@ -132,6 +132,12 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns 
	return ERR_PTR(err);

}



static void delayed_free_pidns(struct rcu_head *p)

{

	kmem_cache_free(pid_ns_cachep,

			container_of(p, struct pid_namespace, rcu));

}



static void destroy_pid_namespace(struct pid_namespace *ns)

{

	int i;
@@ -140,7 +146,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns) 
	for (i = 0; i < PIDMAP_ENTRIES; i++)

		kfree(ns->pidmap[i].page);

	put_user_ns(ns->user_ns);

	kmem_cache_free(pid_ns_cachep, ns);

	call_rcu(&ns->rcu, delayed_free_pidns);

}



struct pid_namespace *copy_pid_ns(unsigned long flags,