Re: [3/3] 2.6.21-rc7: known regressions (v2)

[Ingo Molnar]

just found and fixed the bug below in SysRq-T - should be included in 
v2.6.21 i think.

-------------------------->
Subject: [patch] make SysRq-T show all tasks again
From: Ingo Molnar <mingo@xxxxxxx>

show_state() (SysRq-T) developed the buggy habbit of not showing 
TASK_RUNNING tasks. This was due to the mistaken belief that 
state_filter == -1 would be a pass-through filter - while in reality it 
did not let TASK_RUNNING == 0 p->state values through.

(fix this be restoring the original '!state_filter means all tasks' 
special-case i had in the original version. Test-built and test-booted 
on i686, SysRq-T now works as intended.)

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 include/linux/sched.h |    4 ++--
 kernel/sched.c        |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

Index: linux/include/linux/sched.h
===================================================================
--- linux.orig/include/linux/sched.h
+++ linux/include/linux/sched.h
@@ -196,13 +196,13 @@ extern void init_idle(struct task_struct
 extern cpumask_t nohz_cpu_mask;
 
 /*
- * Only dump TASK_* tasks. (-1 for all tasks)
+ * Only dump TASK_* tasks. (0 for all tasks)
  */
 extern void show_state_filter(unsigned long state_filter);
 
 static inline void show_state(void)
 {
-	show_state_filter(-1);
+	show_state_filter(0);
 }
 
 extern void show_regs(struct pt_regs *);
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -4746,7 +4746,7 @@ void show_state_filter(unsigned long sta
 		 * console might take alot of time:
 		 */
 		touch_nmi_watchdog();
-		if (p->state & state_filter)
+		if (!state_filter || (p->state & state_filter))
 			show_task(p);
 	} while_each_thread(g, p);
 
-
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