1. 20 10月, 2007 2 次提交
    • P
      pid namespaces: changes to show virtual ids to user · b488893a
      Pavel Emelyanov 提交于
      This is the largest patch in the set. Make all (I hope) the places where
      the pid is shown to or get from user operate on the virtual pids.
      
      The idea is:
       - all in-kernel data structures must store either struct pid itself
         or the pid's global nr, obtained with pid_nr() call;
       - when seeking the task from kernel code with the stored id one
         should use find_task_by_pid() call that works with global pids;
       - when showing pid's numerical value to the user the virtual one
         should be used, but however when one shows task's pid outside this
         task's namespace the global one is to be used;
       - when getting the pid from userspace one need to consider this as
         the virtual one and use appropriate task/pid-searching functions.
      
      [akpm@linux-foundation.org: build fix]
      [akpm@linux-foundation.org: nuther build fix]
      [akpm@linux-foundation.org: yet nuther build fix]
      [akpm@linux-foundation.org: remove unneeded casts]
      Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
      Signed-off-by: NAlexey Dobriyan <adobriyan@openvz.org>
      Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
      Cc: Oleg Nesterov <oleg@tv-sign.ru>
      Cc: Paul Menage <menage@google.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b488893a
    • P
      Make access to task's nsproxy lighter · cf7b708c
      Pavel Emelyanov 提交于
      When someone wants to deal with some other taks's namespaces it has to lock
      the task and then to get the desired namespace if the one exists.  This is
      slow on read-only paths and may be impossible in some cases.
      
      E.g.  Oleg recently noticed a race between unshare() and the (sent for
      review in cgroups) pid namespaces - when the task notifies the parent it
      has to know the parent's namespace, but taking the task_lock() is
      impossible there - the code is under write locked tasklist lock.
      
      On the other hand switching the namespace on task (daemonize) and releasing
      the namespace (after the last task exit) is rather rare operation and we
      can sacrifice its speed to solve the issues above.
      
      The access to other task namespaces is proposed to be performed
      like this:
      
           rcu_read_lock();
           nsproxy = task_nsproxy(tsk);
           if (nsproxy != NULL) {
                   / *
                     * work with the namespaces here
                     * e.g. get the reference on one of them
                     * /
           } / *
               * NULL task_nsproxy() means that this task is
               * almost dead (zombie)
               * /
           rcu_read_unlock();
      
      This patch has passed the review by Eric and Oleg :) and,
      of course, tested.
      
      [clg@fr.ibm.com: fix unshare()]
      [ebiederm@xmission.com: Update get_net_ns_by_pid]
      Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
      Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
      Cc: Oleg Nesterov <oleg@tv-sign.ru>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Serge Hallyn <serue@us.ibm.com>
      Signed-off-by: NCedric Le Goater <clg@fr.ibm.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cf7b708c
  2. 19 10月, 2007 6 次提交
  3. 18 10月, 2007 32 次提交