From: Al Viro Date: Thu, 3 Oct 2013 17:28:06 +0000 (-0400) Subject: pid_namespace: make freeing struct pid_namespace rcu-delayed X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=1adfcb03e31ba0d6be5fddf773da4357d0792cbb;p=deliverable%2Flinux.git pid_namespace: make freeing struct pid_namespace rcu-delayed makes procfs ->premission() instances safety in RCU mode independent from vfsmount_lock. Signed-off-by: Al Viro --- diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index e2772666f004..7246ef3d4455 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -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; diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 42086551a24a..06c62de9c711 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -132,6 +132,12 @@ out: 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,