[PATCH] uml: locking documentation

Some locking documentation and a cleanup.  uml_exitcode is copied into a local
before sprintf sees it, in case sprintf does anything non-atomic with it.

The rest are comments about why certain globals don't need any kind of
locking.

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

4 files changed, 8 insertions, 0 deletions

diff --git a/arch/um/drivers/null.c b/arch/um/drivers/null.c
index 3683ed44315d..9016c68beee8 100644
--- a/arch/um/drivers/null.c
+++ b/arch/um/drivers/null.c
@@ -8,6 +8,7 @@
 #include "chan_user.h"
 #include "os.h"
 
+/* This address is used only as a unique identifer */
 static int null_chan;
 
 static void *null_init(char *str, int device, const struct chan_opts *opts)
diff --git a/arch/um/drivers/random.c b/arch/um/drivers/random.c
index ae9909415b9c..73b2bdd6d2d3 100644
--- a/arch/um/drivers/random.c
+++ b/arch/um/drivers/random.c
@@ -20,6 +20,10 @@
 
 #define RNG_MISCDEV_MINOR               183 /* official */
 
+/* Changed at init time, in the non-modular case, and at module load
+ * time, in the module case.  Presumably, the module subsystem
+ * protects against a module being loaded twice at the same time.
+ */
 static int random_fd = -1;
 
 static int rng_dev_open (struct inode *inode, struct file *filp)
diff --git a/arch/um/drivers/stderr_console.c b/arch/um/drivers/stderr_console.c
index 6d2cf32a9e8f..911539293871 100644
--- a/arch/um/drivers/stderr_console.c
+++ b/arch/um/drivers/stderr_console.c
@@ -9,6 +9,8 @@
 /*
  * Don't register by default -- as this registeres very early in the
  * boot process it becomes the default console.
+ *
+ * Initialized at init time.
  */
 static int use_stderr_console = 0;
 
diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
index 5e44adb07051..e4bfcfe8550b 100644
--- a/arch/um/drivers/stdio_console.c
+++ b/arch/um/drivers/stdio_console.c
@@ -108,6 +108,7 @@ static int con_open(struct tty_struct *tty, struct file *filp)
         return line_open(vts, tty);
 }
 
+/* Set in an initcall, checked in an exitcall */
 static int con_init_done = 0;
 
 static const struct tty_operations console_ops = {