Fix a problem with procfs_exit() that resulted in missing some procfs

nodes; this also apparantly caused a panic in some circumstances.
Also, since procfs_exit() is getting rid of the nodes when a process
exits, don't bother checking for the process' existance in procfs_inactive().

4 files changed, 54 insertions, 46 deletions

diff --git a/sys/fs/procfs/procfs_subr.c b/sys/fs/procfs/procfs_subr.c
index e13e425..2156b12 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 1.19 1997/12/08 01:06:22 sef Exp $
+ *	$Id: procfs_subr.c,v 1.20 1997/12/09 05:03:41 sef Exp $
  */
 
 #include <sys/param.h>
@@ -358,16 +358,30 @@ procfs_exit(struct proc *p)
 	struct pfsnode *pfs;
 	pid_t pid = p->p_pid;
 
-	for (pfs = pfshead; pfs ; pfs = pfs->pfs_next) {
-		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);
+	/*
+	 * The reason for this loop is not obvious -- basicly,
+	 * procfs_freevp(), which is called via vgone() (eventually),
+	 * removes the specified procfs node from the pfshead list.
+	 * It does this by *pfsp = pfs->pfs_next, meaning that it
+	 * overwrites the node.  So when we do pfs = pfs->next, we
+	 * end up skipping the node that replaces the one that was
+	 * vgone'd.  Since it may have been the last one on the list,
+	 * it may also have been set to null -- but *our* pfs pointer,
+	 * here, doesn't see this.  So the loop starts from the beginning
+	 * again.
+	 *
+	 * This is not a for() loop because the final event
+	 * would be "pfs = pfs->pfs_next"; in the case where
+	 * pfs is set to pfshead again, that would mean that
+	 * pfshead is skipped over.
+	 *
+	 */
+	pfs = pfshead;
+	while (pfs) {
+		if (pfs->pfs_pid == pid) {
+			vgone(PFSTOV(pfs));
+			pfs = pfshead;
+		} else
+			pfs = pfs->pfs_next;
 	}
 }
diff --git a/sys/fs/procfs/procfs_vnops.c b/sys/fs/procfs/procfs_vnops.c
index f0c1bfb..f660f3a 100644
--- a/sys/fs/procfs/procfs_vnops.c
+++ b/sys/fs/procfs/procfs_vnops.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_vnops.c	8.18 (Berkeley) 5/21/95
  *
- *	$Id: procfs_vnops.c,v 1.45 1997/12/07 04:01:03 sef Exp $
+ *	$Id: procfs_vnops.c,v 1.46 1997/12/08 22:09:24 sef Exp $
  */
 
 /*
@@ -324,13 +324,6 @@ procfs_bmap(ap)
  * list, so to get it back vget() must be
  * used.
  *
- * for procfs, check if the process is still
- * alive and if it isn't then just throw away
- * the vnode by calling vgone().  this may
- * be overkill and a waste of time since the
- * chances are that the process will still be
- * there and PFIND is not free.
- *
  * (vp) is locked on entry, but must be unlocked on exit.
  */
 static int
@@ -340,11 +333,8 @@ procfs_inactive(ap)
 	} */ *ap;
 {
 	struct vnode *vp = ap->a_vp;
-	struct pfsnode *pfs = VTOPFS(vp);
 
 	VOP_UNLOCK(vp, 0, ap->a_p);
-	if (PFIND(pfs->pfs_pid) == 0)
-		vgone(vp);
 
 	return (0);
 }
diff --git a/sys/miscfs/procfs/procfs_subr.c b/sys/miscfs/procfs/procfs_subr.c
index e13e425..2156b12 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 1.19 1997/12/08 01:06:22 sef Exp $
+ *	$Id: procfs_subr.c,v 1.20 1997/12/09 05:03:41 sef Exp $
  */
 
 #include <sys/param.h>
@@ -358,16 +358,30 @@ procfs_exit(struct proc *p)
 	struct pfsnode *pfs;
 	pid_t pid = p->p_pid;
 
-	for (pfs = pfshead; pfs ; pfs = pfs->pfs_next) {
-		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);
+	/*
+	 * The reason for this loop is not obvious -- basicly,
+	 * procfs_freevp(), which is called via vgone() (eventually),
+	 * removes the specified procfs node from the pfshead list.
+	 * It does this by *pfsp = pfs->pfs_next, meaning that it
+	 * overwrites the node.  So when we do pfs = pfs->next, we
+	 * end up skipping the node that replaces the one that was
+	 * vgone'd.  Since it may have been the last one on the list,
+	 * it may also have been set to null -- but *our* pfs pointer,
+	 * here, doesn't see this.  So the loop starts from the beginning
+	 * again.
+	 *
+	 * This is not a for() loop because the final event
+	 * would be "pfs = pfs->pfs_next"; in the case where
+	 * pfs is set to pfshead again, that would mean that
+	 * pfshead is skipped over.
+	 *
+	 */
+	pfs = pfshead;
+	while (pfs) {
+		if (pfs->pfs_pid == pid) {
+			vgone(PFSTOV(pfs));
+			pfs = pfshead;
+		} else
+			pfs = pfs->pfs_next;
 	}
 }
diff --git a/sys/miscfs/procfs/procfs_vnops.c b/sys/miscfs/procfs/procfs_vnops.c
index f0c1bfb..f660f3a 100644
--- a/sys/miscfs/procfs/procfs_vnops.c
+++ b/sys/miscfs/procfs/procfs_vnops.c
@@ -36,7 +36,7 @@
  *
  *	@(#)procfs_vnops.c	8.18 (Berkeley) 5/21/95
  *
- *	$Id: procfs_vnops.c,v 1.45 1997/12/07 04:01:03 sef Exp $
+ *	$Id: procfs_vnops.c,v 1.46 1997/12/08 22:09:24 sef Exp $
  */
 
 /*
@@ -324,13 +324,6 @@ procfs_bmap(ap)
  * list, so to get it back vget() must be
  * used.
  *
- * for procfs, check if the process is still
- * alive and if it isn't then just throw away
- * the vnode by calling vgone().  this may
- * be overkill and a waste of time since the
- * chances are that the process will still be
- * there and PFIND is not free.
- *
  * (vp) is locked on entry, but must be unlocked on exit.
  */
 static int
@@ -340,11 +333,8 @@ procfs_inactive(ap)
 	} */ *ap;
 {
 	struct vnode *vp = ap->a_vp;
-	struct pfsnode *pfs = VTOPFS(vp);
 
 	VOP_UNLOCK(vp, 0, ap->a_p);
-	if (PFIND(pfs->pfs_pid) == 0)
-		vgone(vp);
 
 	return (0);
 }