[PATCH] reset tss->io_bitmap_owner in sys_ioperm()

my patch "x86: initialise tss->io_bitmap_owner to something" (commit ID
d5cd4aadd3d220afac8e3e6d922e333592551f7d) introduced a problem with a
program (DOSEMU) that called ioperm after already doing some port i/o.

The problem is that a process switch return causes tss->io_bitmap_base
to be set to IO_BITMAP_OFFSET so that the fault (that *really* sets the
io bitmap) never triggers.

This fixes that regression.

Signed-off-by: Bart Oldeman <bartoldeman@users.sourceforge.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/i386/kernel/ioport.c b/arch/i386/kernel/ioport.c
index f2b37654777f..b59a34dbe262 100644
--- a/arch/i386/kernel/ioport.c
+++ b/arch/i386/kernel/ioport.c
@@ -108,8 +108,11 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
         /*
          * Sets the lazy trigger so that the next I/O operation will
          * reload the correct bitmap.
+         * Reset the owner so that a process switch will not set
+         * tss->io_bitmap_base to IO_BITMAP_OFFSET.
          */
         tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+        tss->io_bitmap_owner = NULL;
 
         put_cpu();