pid namespaces: destroy pid namespace on init's death

[pandora-kernel.git] / kernel / pid.c

diff --git a/kernel/pid.c b/kernel/pid.c
index d88b83e..b3e6d7c 100644 (file)
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -34,6 +34,7 @@
 #include <linux/hash.h>
 #include <linux/pid_namespace.h>
 #include <linux/init_task.h>
+#include <linux/syscalls.h>
 
 #define pid_hashfn(nr, ns)     \
        hash_long((unsigned long)nr + (unsigned long)ns, pidhash_shift)
@@ -567,6 +568,43 @@ void free_pid_ns(struct kref *kref)
                put_pid_ns(parent);
 }
 
+void zap_pid_ns_processes(struct pid_namespace *pid_ns)
+{
+       int nr;
+       int rc;
+
+       /*
+        * The last thread in the cgroup-init thread group is terminating.
+        * Find remaining pid_ts in the namespace, signal and wait for them
+        * to exit.
+        *
+        * Note:  This signals each threads in the namespace - even those that
+        *        belong to the same thread group, To avoid this, we would have
+        *        to walk the entire tasklist looking a processes in this
+        *        namespace, but that could be unnecessarily expensive if the
+        *        pid namespace has just a few processes. Or we need to
+        *        maintain a tasklist for each pid namespace.
+        *
+        */
+       read_lock(&tasklist_lock);
+       nr = next_pidmap(pid_ns, 1);
+       while (nr > 0) {
+               kill_proc_info(SIGKILL, SEND_SIG_PRIV, nr);
+               nr = next_pidmap(pid_ns, nr);
+       }
+       read_unlock(&tasklist_lock);
+
+       do {
+               clear_thread_flag(TIF_SIGPENDING);
+               rc = sys_wait4(-1, NULL, __WALL, NULL);
+       } while (rc != -ECHILD);
+
+
+       /* Child reaper for the pid namespace is going away */
+       pid_ns->child_reaper = NULL;
+       return;
+}
+
 /*
  * The pid hash table is scaled according to the amount of memory in the
  * machine.  From a minimum of 16 slots up to 4096 slots at one gigabyte or