get_task_state() and task_state_array[] look confusing and suboptimal, it is not clear what it can actually report to user-space and task_state_array[] blows .data for no reason.
1. state = (tsk->state & TASK_REPORT) | tsk->exit_state is not clear. TASK_REPORT is self-documenting but it is not clear what ->exit_state can add. Move the potential exit_state's (EXIT_ZOMBIE and EXIT_DEAD) into TASK_REPORT and use it to calculate the final result. 2. With the change above it is obvious that task_state_array[] has the unused entries just to make BUILD_BUG_ON() happy. Change this BUILD_BUG_ON() to use TASK_REPORT rather than TASK_STATE_MAX and shrink task_state_array[]. 3. Turn the "while (state)" loop into fls(state). Signed-off-by: Oleg Nesterov <[email protected]> --- fs/proc/array.c | 15 +++------------ include/linux/sched.h | 2 +- 2 files changed, 4 insertions(+), 13 deletions(-) diff --git a/fs/proc/array.c b/fs/proc/array.c index cbd0f1b..c995807 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -140,24 +140,15 @@ static const char * const task_state_array[] = { "t (tracing stop)", /* 8 */ "Z (zombie)", /* 16 */ "X (dead)", /* 32 */ - "x (dead)", /* 64 */ - "K (wakekill)", /* 128 */ - "W (waking)", /* 256 */ - "P (parked)", /* 512 */ }; static inline const char *get_task_state(struct task_struct *tsk) { - unsigned int state = (tsk->state & TASK_REPORT) | tsk->exit_state; - const char * const *p = &task_state_array[0]; + unsigned int state = (tsk->state | tsk->exit_state) & TASK_REPORT; - BUILD_BUG_ON(1 + ilog2(TASK_STATE_MAX) != ARRAY_SIZE(task_state_array)); + BUILD_BUG_ON(1 + ilog2(TASK_REPORT) != ARRAY_SIZE(task_state_array)-1); - while (state) { - p++; - state >>= 1; - } - return *p; + return task_state_array[fls(state)]; } static inline void task_state(struct seq_file *m, struct pid_namespace *ns, diff --git a/include/linux/sched.h b/include/linux/sched.h index e27baee..ee2c2e6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -163,7 +163,7 @@ extern char ___assert_task_state[1 - 2*!!( /* get_task_state() */ #define TASK_REPORT (TASK_RUNNING | TASK_INTERRUPTIBLE | \ TASK_UNINTERRUPTIBLE | __TASK_STOPPED | \ - __TASK_TRACED) + __TASK_TRACED | EXIT_ZOMBIE | EXIT_DEAD) #define task_is_traced(task) ((task->state & __TASK_TRACED) != 0) #define task_is_stopped(task) ((task->state & __TASK_STOPPED) != 0) -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
