[RFC 09/16] kgr: mark task_safe in some kthreads

[Jiri Slaby <jslaby@suse.cz>]

Some threads do not use kthread_should_stop. Before we enable a
kthread support in kgr, we must make sure all those mark themselves
safe explicitly.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
---
 drivers/base/devtmpfs.c  | 1 +
 fs/jbd2/journal.c        | 2 ++
 fs/notify/mark.c         | 5 ++++-
 kernel/hung_task.c       | 5 ++++-
 kernel/kthread.c         | 3 +++
 kernel/rcu/tree.c        | 6 ++++--
 kernel/rcu/tree_plugin.h | 9 +++++++--
 kernel/workqueue.c       | 1 +
 8 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c
index 25798db14553..c7d52d1b8c9c 100644
--- a/drivers/base/devtmpfs.c
+++ b/drivers/base/devtmpfs.c
@@ -387,6 +387,7 @@ static int devtmpfsd(void *p)
 	sys_chroot(".");
 	complete(&setup_done);
 	while (1) {
+		kgr_task_safe(current);
 		spin_lock(&req_lock);
 		while (requests) {
 			struct req *req = requests;
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 67b8e303946c..1b9c4c2e014a 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -43,6 +43,7 @@
 #include <linux/backing-dev.h>
 #include <linux/bitops.h>
 #include <linux/ratelimit.h>
+#include <linux/sched.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/jbd2.h>
@@ -260,6 +261,7 @@ loop:
 			write_lock(&journal->j_state_lock);
 		}
 		finish_wait(&journal->j_wait_commit, &wait);
+		kgr_task_safe(current);
 	}
 
 	jbd_debug(1, "kjournald2 wakes\n");
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 923fe4a5f503..a74b6175e645 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -82,6 +82,7 @@
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/srcu.h>
@@ -355,7 +356,9 @@ static int fsnotify_mark_destroy(void *ignored)
 			fsnotify_put_mark(mark);
 		}
 
-		wait_event_interruptible(destroy_waitq, !list_empty(&destroy_list));
+		wait_event_interruptible(destroy_waitq, ({
+					kgr_task_safe(current);
+					!list_empty(&destroy_list); }));
 	}
 
 	return 0;
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 06bb1417b063..b5f85bff2509 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -14,6 +14,7 @@
 #include <linux/kthread.h>
 #include <linux/lockdep.h>
 #include <linux/export.h>
+#include <linux/sched.h>
 #include <linux/sysctl.h>
 #include <linux/utsname.h>
 #include <trace/events/sched.h>
@@ -227,8 +228,10 @@ static int watchdog(void *dummy)
 	for ( ; ; ) {
 		unsigned long timeout = sysctl_hung_task_timeout_secs;
 
-		while (schedule_timeout_interruptible(timeout_jiffies(timeout)))
+		while (schedule_timeout_interruptible(timeout_jiffies(timeout))) {
+			kgr_task_safe(current);
 			timeout = sysctl_hung_task_timeout_secs;
+		}
 
 		if (atomic_xchg(&reset_hung_task, 0))
 			continue;
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 9a130ec06f7a..08b979dad619 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -78,6 +78,8 @@ static struct kthread *to_live_kthread(struct task_struct *k)
  */
 bool kthread_should_stop(void)
 {
+	kgr_task_safe(current);
+
 	return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
 }
 EXPORT_SYMBOL(kthread_should_stop);
@@ -497,6 +499,7 @@ int kthreadd(void *unused)
 		if (list_empty(&kthread_create_list))
 			schedule();
 		__set_current_state(TASK_RUNNING);
+		kgr_task_safe(current);
 
 		spin_lock(&kthread_create_lock);
 		while (!list_empty(&kthread_create_list)) {
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 0c47e300210a..5dddedacfc06 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1593,9 +1593,10 @@ static int __noreturn rcu_gp_kthread(void *arg)
 			trace_rcu_grace_period(rsp->name,
 					       ACCESS_ONCE(rsp->gpnum),
 					       TPS("reqwait"));
-			wait_event_interruptible(rsp->gp_wq,
+			wait_event_interruptible(rsp->gp_wq, ({
+						 kgr_task_safe(current);
 						 ACCESS_ONCE(rsp->gp_flags) &
-						 RCU_GP_FLAG_INIT);
+						 RCU_GP_FLAG_INIT; }));
 			/* Locking provides needed memory barrier. */
 			if (rcu_gp_init(rsp))
 				break;
@@ -1626,6 +1627,7 @@ static int __noreturn rcu_gp_kthread(void *arg)
 					(!ACCESS_ONCE(rnp->qsmask) &&
 					 !rcu_preempt_blocked_readers_cgp(rnp)),
 					j);
+			kgr_task_safe(current);
 			/* Locking provides needed memory barriers. */
 			/* If grace period done, leave loop. */
 			if (!ACCESS_ONCE(rnp->qsmask) &&
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 962d1d589929..8b383003b228 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -27,6 +27,7 @@
 #include <linux/delay.h>
 #include <linux/gfp.h>
 #include <linux/oom.h>
+#include <linux/sched.h>
 #include <linux/smpboot.h>
 #include "../time/tick-internal.h"
 
@@ -1273,7 +1274,8 @@ static int rcu_boost_kthread(void *arg)
 	for (;;) {
 		rnp->boost_kthread_status = RCU_KTHREAD_WAITING;
 		trace_rcu_utilization(TPS("End boost kthread@rcu_wait"));
-		rcu_wait(rnp->boost_tasks || rnp->exp_tasks);
+		rcu_wait(({ kgr_task_safe(current);
+					rnp->boost_tasks || rnp->exp_tasks; }));
 		trace_rcu_utilization(TPS("Start boost kthread@rcu_wait"));
 		rnp->boost_kthread_status = RCU_KTHREAD_RUNNING;
 		more2boost = rcu_boost(rnp);
@@ -2283,11 +2285,14 @@ static int rcu_nocb_kthread(void *arg)
 
 	/* Each pass through this loop invokes one batch of callbacks */
 	for (;;) {
+		kgr_task_safe(current);
 		/* If not polling, wait for next batch of callbacks. */
 		if (!rcu_nocb_poll) {
 			trace_rcu_nocb_wake(rdp->rsp->name, rdp->cpu,
 					    TPS("Sleep"));
-			wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head);
+			wait_event_interruptible(rdp->nocb_wq, ({
+						kgr_task_safe(current);
+						rdp->nocb_head; }));
 			/* Memory barrier provide by xchg() below. */
 		} else if (firsttime) {
 			firsttime = 0;
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0ee63af30bd1..4b89f1dc0dd8 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2369,6 +2369,7 @@ sleep:
 	__set_current_state(TASK_INTERRUPTIBLE);
 	spin_unlock_irq(&pool->lock);
 	schedule();
+	kgr_task_safe(current);
 	goto woke_up;
 }
 
-- 
1.9.2