Code to prevent a panic caused by procfs_exit(). Note that i don't know

what is teh root cause -- but, sometimes, a procfs vnode in pfshead is
apparantly corrupt (or a UFS vnode instead).  Without this patch, I can
get it to panic by doing (in csh)

	while (1)
		ps auxwww
	end

and it will panic when the PID's wrap.  With it, it does not panic.
Yes -- I know that this is NOT the right way to fix it.  But I haven't
been able to get it to panic yet (which confuses me).  I am going to
be looking into the vgone() code now, as that may be a part of it.

2 files changed, 22 insertions, 6 deletions

diff --git a/sys/fs/procfs/procfs_subr.c b/sys/fs/procfs/procfs_subr.c
index 12dcf76..e13e425 100644
--- a/sys/fs/procfs/procfs_subr.c
+++ b/sys/fs/procfs/procfs_subr.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_subr.c	8.6 (Berkeley) 5/14/95
  *
- *	$Id: procfs_subr.c,v 1.18 1997/12/06 04:11:12 sef Exp $
+ *	$Id: procfs_subr.c,v 1.19 1997/12/08 01:06:22 sef Exp $
  */
 
 #include <sys/param.h>
@@ -359,7 +359,15 @@ procfs_exit(struct proc *p)
 	pid_t pid = p->p_pid;
 
 	for (pfs = pfshead; pfs ; pfs = pfs->pfs_next) {
-		if (pfs->pfs_pid == pid)
-			vgone(PFSTOV(pfs));
+		struct vnode *vp = PFSTOV(pfs);
+		/*
+		 * XXX - this is probably over-paranoid here --
+		 * for some reason, occasionally the v_tag is
+		 * not VT_PROCFS; this results in a panic.  I'm
+		 * not sure *why* that is happening.
+		 */
+		if (pfs->pfs_pid == pid && vp->v_usecount &&
+		    vp->v_tag == VT_PROCFS)
+			vgone(vp);
 	}
 }
diff --git a/sys/miscfs/procfs/procfs_subr.c b/sys/miscfs/procfs/procfs_subr.c
index 12dcf76..e13e425 100644
--- a/sys/miscfs/procfs/procfs_subr.c
+++ b/sys/miscfs/procfs/procfs_subr.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_subr.c	8.6 (Berkeley) 5/14/95
  *
- *	$Id: procfs_subr.c,v 1.18 1997/12/06 04:11:12 sef Exp $
+ *	$Id: procfs_subr.c,v 1.19 1997/12/08 01:06:22 sef Exp $
  */
 
 #include <sys/param.h>
@@ -359,7 +359,15 @@ procfs_exit(struct proc *p)
 	pid_t pid = p->p_pid;
 
 	for (pfs = pfshead; pfs ; pfs = pfs->pfs_next) {
-		if (pfs->pfs_pid == pid)
-			vgone(PFSTOV(pfs));
+		struct vnode *vp = PFSTOV(pfs);
+		/*
+		 * XXX - this is probably over-paranoid here --
+		 * for some reason, occasionally the v_tag is
+		 * not VT_PROCFS; this results in a panic.  I'm
+		 * not sure *why* that is happening.
+		 */
+		if (pfs->pfs_pid == pid && vp->v_usecount &&
+		    vp->v_tag == VT_PROCFS)
+			vgone(vp);
 	}
 }