Hi, > -----Original Message----- > From: Eric W. Biederman [mailto:ebiederm@xxxxxxxxxxxx] > Sent: Wednesday, June 18, 2014 9:31 AM > To: Chen, Hanxiao/陈 晗霄 > Cc: containers@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > Andrew Morton; Serge Hallyn; Daniel P. Berrange; Oleg Nesterov; Al Viro; David > Howells; Richard Weinberger; Pavel Emelyanov; Vasiliy Kulikov; Gotou, Yasunori/ > 五? 康文; Linux API; Michael Kerrisk-manpages > Subject: Re: [PATCH] ns: introduce getnspid syscall > > Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx> writes: > > > We need a direct method of getting the pid inside containers. > > If some issues occurred inside container guest, host user > > could not know which process is in trouble just by guest pid: > > the users of container guest only knew the pid inside containers. > > This will bring obstacle for trouble shooting. > > There is also some ongoing work to export this information via a proc > file which seems more appropriate for solving your problem. Certainly > for debugging something easily human discoverable is needed. > Do you mean this patch: /proc/pid/status: show all sets of pid according to ns https://lkml.org/lkml/2014/5/26/145 But no new comments on this patch, Pavel suggested that a syscall should be a good choice. Do we should continue this kind of work? > > int getnspid(pid_t pid, int fd1, int fd2, int pidtype); > > The pidtype is nonsense. The translation of a pid does not depend upon > type. Using that kind of nonsense will lead you and others into confusion. > I see. > > pid: the pid number need to be translated. > > > > fd: a file descriptor referring to one of > > the namespace entries in a /proc/[pid]/ns/pid. > > fd1 for destination ns(ns1), where the pid came from. > > fd2 for reference ns(ns2), while fd2 = -2 means for current ns. > > > > pidtype: 0 PIDTYPE_PID; 1 PIDTYPE_PGID; 2 PIDTYPE_SID. > > > > return value: > > >0: translated pid in ns1(fd1) seen from ns2(fd2). > > <0: on failure. > > Elsewhere we use 0 on pid translation failure. Why be different here? > It should be <=0. And <0 means some other failures. > Eric > > > > Signed-off-by: Chen Hanxiao <chenhanxiao@xxxxxxxxxxxxxx> > > + > > + rcu_read_lock(); > > + task = find_task_by_pid_ns(pid, ns1); > > The functions you want to be using here are: > find_pid_ns and pid_nr_ns. > Thanks for your hint. - Chen
_______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
