From: Måns Rullgård <mru@inprovide.com>
Teach sysrq-N to switch all rt-policy tasks to SCHED_OTHER. For recovering
from (and diagnosing) userspace bugs.
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/drivers/char/sysrq.c | 12 +++++++++++-
25-akpm/include/linux/sched.h | 6 ++++++
25-akpm/kernel/sched.c | 32 ++++++++++++++++++++++++++++++++
3 files changed, 49 insertions(+), 1 deletion(-)
diff -puN drivers/char/sysrq.c~sysrq-n-changes-rt-tasks-to-normal drivers/char/sysrq.c
--- 25/drivers/char/sysrq.c~sysrq-n-changes-rt-tasks-to-normal Mon Nov 1 14:40:17 2004
+++ 25-akpm/drivers/char/sysrq.c Mon Nov 1 14:40:17 2004
@@ -247,6 +247,16 @@ static struct sysrq_key_op sysrq_kill_op
/* END SIGNAL SYSRQ HANDLERS BLOCK */
+static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
+ struct tty_struct *tty)
+{
+ normalize_rt_tasks();
+}
+static struct sysrq_key_op sysrq_unrt_op = {
+ .handler = sysrq_handle_unrt,
+ .help_msg = "Nice",
+ .action_msg = "Nice All RT Tasks"
+};
/* Key Operations table and lock */
static spinlock_t sysrq_key_table_lock = SPIN_LOCK_UNLOCKED;
@@ -281,7 +291,7 @@ static struct sysrq_key_op *sysrq_key_ta
#endif
/* l */ NULL,
/* m */ &sysrq_showmem_op,
-/* n */ NULL,
+/* n */ &sysrq_unrt_op,
/* o */ NULL, /* This will often be registered
as 'Off' at init time */
/* p */ &sysrq_showregs_op,
diff -puN include/linux/sched.h~sysrq-n-changes-rt-tasks-to-normal include/linux/sched.h
--- 25/include/linux/sched.h~sysrq-n-changes-rt-tasks-to-normal Mon Nov 1 14:40:17 2004
+++ 25-akpm/include/linux/sched.h Mon Nov 1 14:40:17 2004
@@ -1125,6 +1125,12 @@ static inline void arch_pick_mmap_layout
extern long sched_setaffinity(pid_t pid, cpumask_t new_mask);
extern long sched_getaffinity(pid_t pid, cpumask_t *mask);
+#ifdef CONFIG_MAGIC_SYSRQ
+
+extern void normalize_rt_tasks(void);
+
+#endif
+
#endif /* __KERNEL__ */
extern void init_sched_domain_sysctl(void);
diff -puN kernel/sched.c~sysrq-n-changes-rt-tasks-to-normal kernel/sched.c
--- 25/kernel/sched.c~sysrq-n-changes-rt-tasks-to-normal Mon Nov 1 14:40:17 2004
+++ 25-akpm/kernel/sched.c Mon Nov 1 14:40:17 2004
@@ -4868,3 +4868,35 @@ void destroy_sched_domain_sysctl()
{
}
#endif
+
+#ifdef CONFIG_MAGIC_SYSRQ
+void normalize_rt_tasks(void)
+{
+ struct task_struct *p;
+ prio_array_t *array;
+ unsigned long flags;
+ runqueue_t *rq;
+
+ read_lock_irq(&tasklist_lock);
+ for_each_process (p) {
+ if (!rt_task(p))
+ continue;
+
+ rq = task_rq_lock(p, &flags);
+
+ array = p->array;
+ if (array)
+ deactivate_task(p, task_rq(p));
+ __setscheduler(p, SCHED_NORMAL, 0);
+ if (array) {
+ __activate_task(p, task_rq(p));
+ resched_task(rq->curr);
+ }
+
+ task_rq_unlock(rq, &flags);
+ }
+ read_unlock_irq(&tasklist_lock);
+}
+
+EXPORT_SYMBOL(normalize_rt_tasks);
+#endif /* CONFIG_MAGIC_SYSRQ */
_