Quoting chenhanxiao@xxxxxxxxxxxxxx (chenhanxiao@xxxxxxxxxxxxxx): > Hi > > > -----Original Message----- > > From: Richard Weinberger [mailto:richard@xxxxxx] > > Sent: Friday, June 20, 2014 7:02 PM > > To: Chen, Hanxiao/陈 晗霄; containers@xxxxxxxxxxxxxxxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx > > Cc: Eric W. Biederman; Serge Hallyn; Daniel P. Berrange; Oleg Nesterov; Al Viro; > > David Howells; Pavel Emelyanov; Vasiliy Kulikov; Gotou, Yasunori/五島 康文; > > linux-api@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH v2] ns: introduce getnspid syscall > > > > Am 20.06.2014 12:18, schrieb Chen Hanxiao: > > > 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. > > > > > > int getnspid(pid_t pid, int fd1, int fd2); > > > > > > 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. > > > > > > return value: > > > >0 : translated pid in ns1(fd1) seen from ns2(fd2). > > > <=0: on failure. > > > > > > > I don't think that adding a new system call for this is a good solution. > > We need a more generic way. I bet people are interested in more than just PID > > numbers. > > Could you please give some hints on how to expand this interface? > > > > > I agree with Eric that a procfs solution is more appropriate. > > > > Procfs is a good solution, but syscall is not bad though. I might be inclined to agree, except that in this case you are still needing mounted procfs anyway to get the proc/$pid/ns/pid fds. I'm sorry, I've not been watching this thread, so this probably has been considered and decided against, but I'm going to ask anyway. Keeping in mind both checkpoint-restart and and introspection for use in a setns'd commend, why not make it pid_t getnspid(pid_t query_pid, pid_t observer_pid) which returns the process id of query_pid as seen from observer_pid's pidns? > Procfs works for me, but that seems could not fit > Pavel's requirement. > His opinion is that a syscall is a more generic interface > than proc files, and also very helpful. > And syscall could tell whether a pid lives in a specific pid namespace, > much convenient than procfs. > > Thanks, > - Chen > _______________________________________________ > Containers mailing list > Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx > https://lists.linuxfoundation.org/mailman/listinfo/containers -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
