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authorEric W. Biederman <ebiederm@xmission.com>2012-08-01 10:33:47 -0700
committerEric W. Biederman <ebiederm@xmission.com>2012-11-19 05:59:10 -0800
commit0a01f2cc390e10633a54f72c608cc3fe19a50c3d (patch)
treee713a1c45b5ce125a5d33b61d528cd45264d47a7 /include/linux/pid_namespace.h
parent17cf22c33e1f1b5e435469c84e43872579497653 (diff)
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pidns: Make the pidns proc mount/umount logic obvious.
Track the number of pids in the proc hash table. When the number of pids goes to 0 schedule work to unmount the kernel mount of proc. Move the mount of proc into alloc_pid when we allocate the pid for init. Remove the surprising calls of pid_ns_release proc in fork and proc_flush_task. Those code paths really shouldn't know about proc namespace implementation details and people have demonstrated several times that finding and understanding those code paths is difficult and non-obvious. Because of the call path detach pid is alwasy called with the rtnl_lock held free_pid is not allowed to sleep, so the work to unmounting proc is moved to a work queue. This has the side benefit of not blocking the entire world waiting for the unnecessary rcu_barrier in deactivate_locked_super. In the process of making the code clear and obvious this fixes a bug reported by Gao feng <gaofeng@cn.fujitsu.com> where we would leak a mount of proc during clone(CLONE_NEWPID|CLONE_NEWNET) if copy_pid_ns succeeded and copy_net_ns failed. Acked-by: "Serge E. Hallyn" <serge@hallyn.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'include/linux/pid_namespace.h')
-rw-r--r--include/linux/pid_namespace.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index c89c9cfcd247..4c96acdb2489 100644
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -21,6 +21,7 @@ struct pid_namespace {
struct kref kref;
struct pidmap pidmap[PIDMAP_ENTRIES];
int last_pid;
+ int nr_hashed;
struct task_struct *child_reaper;
struct kmem_cache *pid_cachep;
unsigned int level;
@@ -32,6 +33,7 @@ struct pid_namespace {
struct bsd_acct_struct *bacct;
#endif
struct user_namespace *user_ns;
+ struct work_struct proc_work;
kgid_t pid_gid;
int hide_pid;
int reboot; /* group exit code if this pidns was rebooted */