[RFC] "biological parent" pid

From: Tim Schmielau (tim_at_physik3.uni-rostock.de)
Date: 01/31/05

  • Next message: Arnd Bergmann: "Re: [PATCH] Fix SERIAL_TXX9 dependencies" 
    Date:	Mon, 31 Jan 2005 22:38:41 +0100 (CET)
To: lkml <linux-kernel@vger.kernel.org>

    The ppid of a process is not really helpful if I want to reconstruct the
    real history of processes on a machine, since it may become 1 when the
    parent dies and the process is reparented to init.

    I am not aware of concepts in Linux or other unices that apply to this
    case. So I made up the "biological parent pid" bioppid (in contrast to the
    adoptive parents pid) that just never changes.
    Any user of it must of course remember that it doesn't need to be a valid
    pid anymore or might even belong to a different process that was forked in
    the meantime. bioppid only had to be a valid pid at time btime (it's
    a (btime, pid) pair that unambiguously identifies a process).

    Comments? (other that I just broke /proc/nnn/status parsing once again :-)

    Tim

    --- linux-2.6.10/include/linux/sched.h 2004-12-24 22:33:59.000000000 +0100
    +++ linux-2.6.10-ppid/include/linux/sched.h 2005-01-31 19:20:00.000000000 +0100
    @@ -556,6 +556,7 @@ struct task_struct {
             unsigned did_exec:1;
             pid_t pid;
             pid_t tgid;
    + pid_t bioppid; /* biological parents */
             /*
              * pointers to (original) parent process, youngest child, younger sibling,
              * older sibling, respectively. (p->father can be replaced with

    --- linux-2.6.10/kernel/fork.c 2004-12-24 22:33:59.000000000 +0100
    +++ linux-2.6.10-ppid/kernel/fork.c 2005-01-31 18:15:39.000000000 +0100
    @@ -889,6 +889,7 @@ static task_t *copy_process(unsigned lon
             p->tgid = p->pid;
             if (clone_flags & CLONE_THREAD)
                     p->tgid = current->tgid;
    + p->bioppid = current->pid;
     
             if ((retval = security_task_alloc(p)))
                     goto bad_fork_cleanup_policy;

    --- linux-2.6.10/fs/proc/array.c 2004-12-24 22:35:00.000000000 +0100
    +++ linux-2.6.10-ppid/fs/proc/array.c 2005-01-31 18:19:02.000000000 +0100
    @@ -165,6 +165,7 @@ static inline char * task_state(struct t
                     "Tgid:\t%d\n"
                     "Pid:\t%d\n"
                     "PPid:\t%d\n"
    + "BioPPid:\t%d\n"
                     "TracerPid:\t%d\n"
                     "Uid:\t%d\t%d\t%d\t%d\n"
                     "Gid:\t%d\t%d\t%d\t%d\n",
    @@ -172,6 +173,7 @@ static inline char * task_state(struct t
                     (p->sleep_avg/1024)*100/(1020000000/1024),
                            p->tgid,
                     p->pid, pid_alive(p) ? p->group_leader->real_parent->tgid : 0,
    + p->bioppid,
                     pid_alive(p) && p->ptrace ? p->parent->pid : 0,
                     p->uid, p->euid, p->suid, p->fsuid,
                     p->gid, p->egid, p->sgid, p->fsgid);

    --- linux-2.6.10/kernel/acct.c 2004-12-24 22:34:58.000000000 +0100
    +++ linux-2.6.10-ppid/kernel/acct.c 2005-01-31 18:19:35.000000000 +0100
    @@ -446,7 +446,7 @@ static void do_acct_process(long exitcod
     #endif
     #if ACCT_VERSION==3
             ac.ac_pid = current->tgid;
    - ac.ac_ppid = current->parent->tgid;
    + ac.ac_ppid = current->bioppid;
     #endif
     
             read_lock(&tasklist_lock); /* pin current->signal */
    -
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