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Commit e59e2ae2 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] SysRq-X: show blocked tasks 



Add SysRq-X support: show blocked (TASK_UNINTERRUPTIBLE) tasks only.

Useful for debugging IO stalls.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 875d95ec

drivers/char/sysrq.c

+13 −1
Original line number Diff line number Diff line
@@ -182,6 +182,18 @@ static struct sysrq_key_op sysrq_showstate_op = { 
	.enable_mask	= SYSRQ_ENABLE_DUMP,

};



static void sysrq_handle_showstate_blocked(int key, struct tty_struct *tty)

{

	show_state_filter(TASK_UNINTERRUPTIBLE);

}

static struct sysrq_key_op sysrq_showstate_blocked_op = {

	.handler	= sysrq_handle_showstate_blocked,

	.help_msg	= "showBlockedTasks",

	.action_msg	= "Show Blocked State",

	.enable_mask	= SYSRQ_ENABLE_DUMP,

};





static void sysrq_handle_showmem(int key, struct tty_struct *tty)

{

	show_mem();
@@ -304,7 +316,7 @@ static struct sysrq_key_op *sysrq_key_table[36] = { 
	/* May be assigned at init time by SMP VOYAGER */

	NULL,				/* v */

	NULL,				/* w */

	NULL,				/* x */

	&sysrq_showstate_blocked_op,	/* x */

	NULL,				/* y */

	NULL				/* z */

};

include/linux/sched.h

+10 −1
Original line number Diff line number Diff line
@@ -194,7 +194,16 @@ extern void init_idle(struct task_struct *idle, int cpu); 


extern cpumask_t nohz_cpu_mask;



extern void show_state(void);

/*

 * Only dump TASK_* tasks. (-1 for all tasks)

 */

extern void show_state_filter(unsigned long state_filter);



static inline void show_state(void)

{

	show_state_filter(-1);

}



extern void show_regs(struct pt_regs *);



/*

kernel/sched.c

+8 −3
Original line number Diff line number Diff line
@@ -4804,7 +4804,7 @@ static void show_task(struct task_struct *p) 
		show_stack(p, NULL);

}



void show_state(void)

void show_state_filter(unsigned long state_filter)

{

	struct task_struct *g, *p;
@@ -4824,10 +4824,15 @@ void show_state(void) 
		 * console might take alot of time:

		 */

		touch_nmi_watchdog();

		if (p->state & state_filter)

			show_task(p);

	} while_each_thread(g, p);



	read_unlock(&tasklist_lock);

	/*

	 * Only show locks if all tasks are dumped:

	 */

	if (state_filter == -1)

		debug_show_all_locks();

}