[hurd] 04/05: proc: Remove erroneous process entry.

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit fb3698ebbb375472832939d5534363d42de624f2
Author: Justus Winter <address@hidden>
Date:   Thu Mar 9 23:10:05 2017 +0100

    proc: Remove erroneous process entry.
    
    Previously, there was a spurious copy of PID 1 in the process table,
    usually PID 8.  PID 1, usually a sysvinit compatible process, needs to
    be PID 1 even though it is not actually the first process on the Hurd.
    To this end, PID 1 is reserved, and the task is later supplied to proc
    via proc_set_init_task once startup starts sysvinit.
    
    Fixes 8d16db0cc28b2d911aee918d5c3582ad29ddfeed.
    
    * proc/mgt.c (S_proc_set_init_task): Check if sysvinit's task already
    made it into the process table, and remove it if so.
---
 proc/mgt.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/proc/mgt.c b/proc/mgt.c
index dc3a19e..831a351 100644
--- a/proc/mgt.c
+++ b/proc/mgt.c
@@ -966,17 +966,46 @@ genpid ()
   return nextpid++;
 }
 
+
+
+/* Support for making sysvinit PID 1.  */
+
+/* We reserve PID 1 for sysvinit.  However, proc may pick up the task
+   when it is created and reserve an entry in the process table for
+   it.  When startup tells us the task that it created for sysvinit,
+   we need to locate this preliminary entry and remove it.  Otherwise,
+   we end up with two entries for sysvinit with the same task.  */
+
+/* XXX: This is a mess.  It would be nicer if startup gave us the
+   ports (e.g. sysvinit's task, the kernel task...) before starting
+   us, communicating the names using command line options.  */
+
 /* Implement proc_set_init_task as described in <hurd/process.defs>.  */
 error_t
 S_proc_set_init_task(struct proc *callerp,
                     task_t task)
 {
+  struct proc *shadow;
+
   if (! callerp)
     return EOPNOTSUPP;
 
   if (callerp != startup_proc)
     return EPERM;
 
+  /* Check if TASK already made it into the process table, and if so
+     remove it.  */
+  shadow = task_find_nocreate (task);
+  if (shadow)
+    {
+      /* Cheat a little so we can use complete_exit.  */
+      shadow->p_dead = 1;
+      shadow->p_waited = 1;
+      mach_port_deallocate (mach_task_self (), shadow->p_task);
+      shadow->p_task = MACH_PORT_NULL;
+      complete_exit (shadow);
+    }
+
   init_proc->p_task = task;
   proc_death_notify (init_proc);
   add_proc_to_hash (init_proc);
@@ -984,6 +1013,8 @@ S_proc_set_init_task(struct proc *callerp,
   return 0;
 }
 
+
+
 /* Implement proc_mark_important as described in <hurd/process.defs>. */
 kern_return_t
 S_proc_mark_important (struct proc *p)

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