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| author | Eric W. Biederman <ebiederm@xmission.com> | 2012-08-01 21:33:47 +0400 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-11-19 17:59:10 +0400 |
| commit | 0a01f2cc390e10633a54f72c608cc3fe19a50c3d (patch) | |
| tree | e713a1c45b5ce125a5d33b61d528cd45264d47a7 /include/linux/pid_namespace.h | |
| parent | 17cf22c33e1f1b5e435469c84e43872579497653 (diff) | |
| download | linux-0a01f2cc390e10633a54f72c608cc3fe19a50c3d.tar.xz | |
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.h | 2 |
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 */ |