uml: SMP locking commentary

Add some more commentary about various pieces of global data not needing
locking.

Also got rid of unmap_physmem since that is no longer used.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 663011c2983f..d948babfc67a 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -22,17 +22,20 @@
 unsigned long *empty_zero_page = NULL;
 /* allocated in paging_init and unchanged thereafter */
 unsigned long *empty_bad_page = NULL;
+
+/*
+ * Initialized during boot, and readonly for initializing page tables
+ * afterwards
+ */
 pgd_t swapper_pg_dir[PTRS_PER_PGD];
+
+/* Initialized at boot time, and readonly after that */
 unsigned long long highmem;
 int kmalloc_ok = 0;
 
+/* Used during early boot */
 static unsigned long brk_end;
 
-void unmap_physmem(void)
-{
-        os_unmap_memory((void *) brk_end, uml_reserved - brk_end);
-}
-
 static void map_cb(void *unused)
 {
         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);