proc: cleanup/simplify get_task_state/task_state_array (74e37200) · Commits · 戴 / test

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 <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Laight <David.Laight@ACULAB.COM> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/array.c

+3 −12

Original line number	Diff line number	Diff line
		@@ -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,

include/linux/sched.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -229,7 +229,7 @@ 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)

Admin message