svn commit: r184417 - in stable/7/sys: . kern

[Christian S.J. Peron]

Author: csjp
Date: Tue Oct 28 17:01:16 2008
New Revision: 184417
URL: http://svn.freebsd.org/changeset/base/184417

Log:
  MFC SVN rev 181647
  
  - Reduce the scope of the vnode lock such that it does not
    cover the various copyouts associated with initializing
    the process's argv/env data in userspace.  It is possible
    that these copyout operations can fault under memory
    pressure, possibly resulting in dead locks.
  
  Approved by:	re@ (kib)

Modified:
  stable/7/sys/   (props changed)
  stable/7/sys/kern/kern_exec.c

Modified: stable/7/sys/kern/kern_exec.c
==============================================================================
--- stable/7/sys/kern/kern_exec.c	Tue Oct 28 15:17:59 2008	(r184416)
+++ stable/7/sys/kern/kern_exec.c	Tue Oct 28 17:01:16 2008	(r184417)
@@ -476,6 +476,11 @@ interpret:
 	}
 
 	/*
+	 * NB: We unlock the vnode here because it is believed that none
+	 * of the sv_copyout_strings/sv_fixup operations require the vnode.
+	 */
+	VOP_UNLOCK(imgp->vp, 0, td);
+	/*
 	 * Copy out strings (args and env) and initialize stack base
 	 */
 	if (p->p_sysent->sv_copyout_strings)
@@ -512,7 +517,6 @@ interpret:
 	}
 
 	/* close files on exec */
-	VOP_UNLOCK(imgp->vp, 0, td);
 	fdcloseexec(td);
 	vn_lock(imgp->vp, LK_EXCLUSIVE | LK_RETRY, td);