提交 74e37200 编写于 作者: O Oleg Nesterov 提交者: Linus Torvalds

proc: cleanup/simplify get_task_state/task_state_array

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: NOleg 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 942be387
......@@ -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,
......
......@@ -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)
......
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