Commit 051a1d1a authored by Dmitry Adamushko's avatar Dmitry Adamushko Committed by Ingo Molnar
Browse files

sched: fix crash on ia64, introduce task_current() 

Some services (e.g. sched_setscheduler(), rt_mutex_setprio() and
sched_move_task()) must handle a given task differently in case it's the
'rq->curr' task on its run-queue. The task_running() interface is not
suitable for determining such tasks for platforms with one of the
following options:

#define __ARCH_WANT_UNLOCKED_CTXSW
#define __ARCH_WANT_INTERRUPTS_ON_CTXSW

Due to the fact that it makes use of 'p->oncpu == 1' as a criterion but
such a task is not necessarily 'rq->curr'.

The detailed explanation is available here:
https://lists.linux-foundation.org/pipermail/containers/2007-December/009262.html



Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Tested-by: default avatarDhaval Giani <dhaval@linux.vnet.ibm.com>
Tested-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
parent c63a1190

kernel/sched.c

+11 −6
Original line number Diff line number Diff line
@@ -508,10 +508,15 @@ EXPORT_SYMBOL_GPL(cpu_clock); 
# define finish_arch_switch(prev)	do { } while (0)

#endif



static inline int task_current(struct rq *rq, struct task_struct *p)

{

	return rq->curr == p;

}



#ifndef __ARCH_WANT_UNLOCKED_CTXSW

static inline int task_running(struct rq *rq, struct task_struct *p)

{

	return rq->curr == p;

	return task_current(rq, p);

}



static inline void prepare_lock_switch(struct rq *rq, struct task_struct *next)
@@ -540,7 +545,7 @@ static inline int task_running(struct rq *rq, struct task_struct *p) 
#ifdef CONFIG_SMP

	return p->oncpu;

#else

	return rq->curr == p;

	return task_current(rq, p);

#endif

}
@@ -3334,7 +3339,7 @@ unsigned long long task_sched_runtime(struct task_struct *p) 


	rq = task_rq_lock(p, &flags);

	ns = p->se.sum_exec_runtime;

	if (rq->curr == p) {

	if (task_current(rq, p)) {

		update_rq_clock(rq);

		delta_exec = rq->clock - p->se.exec_start;

		if ((s64)delta_exec > 0)
@@ -4021,7 +4026,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio) 


	oldprio = p->prio;

	on_rq = p->se.on_rq;

	running = task_running(rq, p);

	running = task_current(rq, p);

	if (on_rq) {

		dequeue_task(rq, p, 0);

		if (running)
@@ -4332,7 +4337,7 @@ recheck: 
	}

	update_rq_clock(rq);

	on_rq = p->se.on_rq;

	running = task_running(rq, p);

	running = task_current(rq, p);

	if (on_rq) {

		deactivate_task(rq, p, 0);

		if (running)
@@ -7101,7 +7106,7 @@ void sched_move_task(struct task_struct *tsk) 


	update_rq_clock(rq);



	running = task_running(rq, tsk);

	running = task_current(rq, tsk);

	on_rq = tsk->se.on_rq;



	if (on_rq) {

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