[snip]
diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 525d8fc..74f21fe 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -32,8 +32,14 @@ struct nsproxy { }; extern struct nsproxy init_nsproxy; +static inline struct nsproxy *task_nsproxy(struct task_struct *tsk) +{ + return rcu_dereference(tsk->nsproxy); +}Looks like a very nice cleanup as well. But please add a comment above task_nsproxy() that it must be called under rcu_read_lock() or task_lock(task) (though I'll admit the rcu_dereference may make that obvious)
I will, but I think that rcu_dereference implies this. Anyway. [snip]
+ if (ns == new) + return; + + if (new) + get_nsproxy(new); + rcu_assign_pointer(p->nsproxy, new); + + if (ns && atomic_dec_and_test(&ns->count)) { + /* + * wait for others to get what they want from this + * nsproxy. cannot release this nsproxy via the + * call_rcu() since put_mnt_ns will want to sleep + */ + synchronize_rcu(); + free_nsproxy(ns); + } +}Also a comment above switch_task_namespaces() that it must be called with task_lock held.
no! no locks here! free_nsproxy() may sleep when putting mnt_ns and maybe some other. see - there's a hunk in sys_unshare that move the task_lock() after switch_task_namespaces().
thanks, -serge
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