Author: kib
Date: Sun Apr 10 17:07:02 2011
New Revision: 220526
URL: http://svn.freebsd.org/changeset/base/220526

Log:
  Some callers of proc_reparent() already have the parent process locked.
  Detect the situation and avoid process lock recursion.
  
  Reported by:  Fabian Keil <freebsd-listen fabiankeil de>

Modified:
  head/sys/kern/kern_exit.c

Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c   Sun Apr 10 15:48:16 2011        (r220525)
+++ head/sys/kern/kern_exit.c   Sun Apr 10 17:07:02 2011        (r220526)
@@ -903,15 +903,19 @@ loop:
 void
 proc_reparent(struct proc *child, struct proc *parent)
 {
+       int locked;
 
        sx_assert(&proctree_lock, SX_XLOCKED);
        PROC_LOCK_ASSERT(child, MA_OWNED);
        if (child->p_pptr == parent)
                return;
 
-       PROC_LOCK(parent);
+       locked = PROC_LOCKED(parent);
+       if (!locked)
+               PROC_LOCK(parent);
        racct_add_force(parent, RACCT_NPROC, 1);
-       PROC_UNLOCK(parent);
+       if (!locked)
+               PROC_UNLOCK(parent);
        PROC_LOCK(child->p_pptr);
        racct_sub(child->p_pptr, RACCT_NPROC, 1);
        sigqueue_take(child->p_ksi);
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