sched/debug: Ignore TASK_IDLE for SysRq-W

Markus reported that tasks in TASK_IDLE state are reported by SysRq-W,
which results in undesirable clutter.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 23 insertions, 1 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 18a6966567da..d17c5da523a0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5166,6 +5166,28 @@ void sched_show_task(struct task_struct *p)
         put_task_stack(p);
 }
 
+static inline bool
+state_filter_match(unsigned long state_filter, struct task_struct *p)
+{
+        /* no filter, everything matches */
+        if (!state_filter)
+                return true;
+
+        /* filter, but doesn't match */
+        if (!(p->state & state_filter))
+                return false;
+
+        /*
+         * When looking for TASK_UNINTERRUPTIBLE skip TASK_IDLE (allows
+         * TASK_KILLABLE).
+         */
+        if (state_filter == TASK_UNINTERRUPTIBLE && p->state == TASK_IDLE)
+                return false;
+
+        return true;
+}
+
+
 void show_state_filter(unsigned long state_filter)
 {
         struct task_struct *g, *p;
@@ -5188,7 +5210,7 @@ void show_state_filter(unsigned long state_filter)
                  */
                 touch_nmi_watchdog();
                 touch_all_softlockup_watchdogs();
-                if (!state_filter || (p->state & state_filter))
+                if (state_filter_match(state_filter, p))
                         sched_show_task(p);
         }