sched: Assert task state bits at build time

Since everybody is lazy and prone to forgetting things, make the
compiler help us a bit.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20091217121830.060186433@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 10 insertions, 8 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 96361e8fa3a..f560325c444 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -134,14 +134,14 @@ static inline void task_name(struct seq_file *m, struct task_struct *p)
  * simple bit tests.
  */
 static const char *task_state_array[] = {
-        "R (running)",          /*  0 */
-        "S (sleeping)",         /*  1 */
-        "D (disk sleep)",       /*  2 */
-        "T (stopped)",          /*  4 */
-        "t (tracing stop)",     /*  8 */
-        "Z (zombie)",           /* 16 */
-        "X (dead)",             /* 32 */
-        "x (dead)",             /* 64 */
+        "R (running)",          /*   0 */
+        "S (sleeping)",         /*   1 */
+        "D (disk sleep)",       /*   2 */
+        "T (stopped)",          /*   4 */
+        "t (tracing stop)",     /*   8 */
+        "Z (zombie)",           /*  16 */
+        "X (dead)",             /*  32 */
+        "x (dead)",             /*  64 */
         "K (wakekill)",         /* 128 */
         "W (waking)",           /* 256 */
 };
@@ -151,6 +151,8 @@ static inline const char *get_task_state(struct task_struct *tsk)
         unsigned int state = (tsk->state & TASK_REPORT) | tsk->exit_state;
         const char **p = &task_state_array[0];
 
+        BUILD_BUG_ON(1 + ilog2(TASK_STATE_MAX) != ARRAY_SIZE(task_state_array));
+
         while (state) {
                 p++;
                 state >>= 1;