vserver 1.9.3

[linux-2.6.git] / arch / i386 / kernel / ioport.c

diff --git a/arch/i386/kernel/ioport.c b/arch/i386/kernel/ioport.c
index 3346657..8b25160 100644 (file)
--- a/arch/i386/kernel/ioport.c
+++ b/arch/i386/kernel/ioport.c
@@ -56,6 +56,7 @@ static void set_bitmap(unsigned long *bitmap, unsigned int base, unsigned int ex
  */
 asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 {
+       unsigned long i, max_long, bytes, bytes_updated;
        struct thread_struct * t = &current->thread;
        struct tss_struct * tss;
        unsigned long *bitmap;
@@ -81,16 +82,37 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 
        /*
         * do it in the per-thread copy and in the TSS ...
+        *
+        * Disable preemption via get_cpu() - we must not switch away
+        * because the ->io_bitmap_max value must match the bitmap
+        * contents:
         */
+       tss = &per_cpu(init_tss, get_cpu());
+
        set_bitmap(t->io_bitmap_ptr, from, num, !turn_on);
-       tss = init_tss + get_cpu();
-       if (tss->io_bitmap_base == IO_BITMAP_OFFSET) { /* already active? */
-               set_bitmap(tss->io_bitmap, from, num, !turn_on);
-       } else {
-               memcpy(tss->io_bitmap, t->io_bitmap_ptr, IO_BITMAP_BYTES);
-               tss->io_bitmap_base = IO_BITMAP_OFFSET; /* Activate it in the TSS */
-       }
+
+       /*
+        * Search for a (possibly new) maximum. This is simple and stupid,
+        * to keep it obviously correct:
+        */
+       max_long = 0;
+       for (i = 0; i < IO_BITMAP_LONGS; i++)
+               if (t->io_bitmap_ptr[i] != ~0UL)
+                       max_long = i;
+
+       bytes = (max_long + 1) * sizeof(long);
+       bytes_updated = max(bytes, t->io_bitmap_max);
+
+       t->io_bitmap_max = bytes;
+
+       /*
+        * Sets the lazy trigger so that the next I/O operation will
+        * reload the correct bitmap.
+        */
+       tss->io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
+
        put_cpu();
+
        return 0;
 }