On 06/10/2011 11:46 AM, Greg Kurz wrote: > Since pid namespaces were introduced, there's a recurring demand: how one > can correlate a pid from a child pid ns with a pid from a parent pid ns ? > The need arises in the LXC community when one wants to send a signal from > the host (aka. init_pid_ns context) to a container process for which one > only knows the pid inside the container. > > In the future, this should be achievable thanks to Eric Biederman's setns() > syscall but there's still some work to be done to support pid namespaces: > > https://lkml.org/lkml/2011/5/21/162 > > As stated by Serge Hallyn in: > > http://sourceforge.net/mailarchive/message.php?msg_id=27424447 > > "There is nothing that gives you a 100% guaranteed correct race-free > correspondence right now. You can look under /proc/<pid>/root/proc/ to > see the pids valid in the container, and you can relate output of > lxc-ps --forest to ps --forest output. But nothing under /proc that I > know of tells you "this task is the same as that task". You can't > even look at /proc/<pid> inode numbers since they are different > filesystems for each proc mount." > > This patch adds a single line to /proc/self/status. Provided one has kept > track of its container tasks (with a cgroup like liblxc does for example), > he may correlate global pids and container pids. This is still racy but > definitely easier than what we have today. > > Signed-off-by: Greg Kurz <gkurz@xxxxxxxxxx> Acked-by: Cedric Le Goater <clg@xxxxxxxxxx> Thanks, C. > --- > > fs/proc/array.c | 8 ++++++-- > 1 files changed, 6 insertions(+), 2 deletions(-) > > diff --git a/fs/proc/array.c b/fs/proc/array.c > index 5e4f776..f9db2a4 100644 > --- a/fs/proc/array.c > +++ b/fs/proc/array.c > @@ -165,7 +165,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, > int g; > struct fdtable *fdt = NULL; > const struct cred *cred; > - pid_t ppid, tpid; > + struct pid_namespace *pid_ns; > + pid_t ppid, tpid, vpid; > > rcu_read_lock(); > ppid = pid_alive(p) ? > @@ -176,6 +177,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, > if (tracer) > tpid = task_pid_nr_ns(tracer, ns); > } > + pid_ns = task_active_pid_ns(p); > + vpid = pid_ns ? task_pid_nr_ns(p, pid_ns) : 0; > cred = get_task_cred(p); > seq_printf(m, > "State:\t%s\n" > @@ -183,12 +186,13 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns, > "Pid:\t%d\n" > "PPid:\t%d\n" > "TracerPid:\t%d\n" > + "VPid:\t%d\n" > "Uid:\t%d\t%d\t%d\t%d\n" > "Gid:\t%d\t%d\t%d\t%d\n", > get_task_state(p), > task_tgid_nr_ns(p, ns), > pid_nr_ns(pid, ns), > - ppid, tpid, > + ppid, tpid, vpid, > cred->uid, cred->euid, cred->suid, cred->fsuid, > cred->gid, cred->egid, cred->sgid, cred->fsgid); > > _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
