From: Matthew Dillon <dillon@apollo.backplane.com>
Date: Thu, 22 Mar 2018 01:11:10 +0000 (-0700)
Subject: kernel - Fix tapN creation >= 32 units, fix pty issues >= 32 ptys
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/095422fab17a80173d19945ec66d07cdd9fa1b44

kernel - Fix tapN creation >= 32 units, fix pty issues >= 32 ptys

* Fix ifconfig tapN create for N >= 32.

* devfs_clone_bitmap_chk(), which only if_tap uses, was returning
  the wrong default value for unit numbers beyond the current
  dynamic size of the bitmap.

* Both devfs_clone_bitmap_chk() and devfs_clone_bitmap_put()
  were improperly using (1 << unit) instead of (1L << unit)
  when masking the 64-bit (long) bitmap elements, resulting in
  chaos for units >= 32.

* This also should fix pty issues >= 32 ptys.

Reported-by: Aaron Li
---

diff --git a/sys/vfs/devfs/devfs_helper.c b/sys/vfs/devfs/devfs_helper.c
index a3807588b4..c906e22429 100644
--- a/sys/vfs/devfs/devfs_helper.c
+++ b/sys/vfs/devfs/devfs_helper.c
@@ -104,7 +104,13 @@ devfs_clone_bitmap_fff(struct devfs_bitmap *bitmap)
 	return -1;
 }
 
-
+/*
+ * Caller wants to know if the specified unit has been allocated
+ * or not.  Return 0, indicating that it has not been allocated.
+ *
+ * (the bitmap implements 0=allocated, 1=not-allocated but the
+ * return value is inverted).
+ */
 int
 devfs_clone_bitmap_chk(struct devfs_bitmap *bitmap, int unit)
 {
@@ -114,9 +120,9 @@ devfs_clone_bitmap_chk(struct devfs_bitmap *bitmap, int unit)
 	unit -= chunk * (sizeof(u_long) * 8);
 
 	if (chunk >= bitmap->chunks)
-		return 1;
+		return 0;		/* device does not exist */
 
-	return !((bitmap->bitmap[chunk]) & (1 << unit));
+	return !((bitmap->bitmap[chunk]) & (1L << unit));
 }
 
 
@@ -150,7 +156,7 @@ devfs_clone_bitmap_put(struct devfs_bitmap *bitmap, int unit)
 
 	if (chunk >= bitmap->chunks)
 		return;
-	bitmap->bitmap[chunk] |= (1 << unit);
+	bitmap->bitmap[chunk] |= (1L << unit);
 }
 
 /*