From: Aaron Taylor <ataylor@subgeniuskitty.com>
Date: Wed, 28 Apr 2021 08:01:31 +0000 (-0700)
Subject: Updated host/linvcons.c to use new timer API introduced in Linux 4.14.0.
X-Git-Tag: first-build~23
X-Git-Url: https://git.subgeniuskitty.com/xeon-phi-kernel-module/.git/commitdiff_plain/f4a476d15921ee97ff3f23147e5119e25bc561cb

Updated host/linvcons.c to use new timer API introduced in Linux 4.14.0.

See also:

  - https://lwn.net/Articles/735887/

  - https://stackoverflow.com/questions/53839625
---

diff --git a/host/linvcons.c b/host/linvcons.c
index 556a9b5..7c3e58d 100644
--- a/host/linvcons.c
+++ b/host/linvcons.c
@@ -43,7 +43,7 @@ static int micvcons_write(struct tty_struct * tty, const unsigned char *buf,
 								int count);
 static int micvcons_write_room(struct tty_struct *tty);
 static void micvcons_set_termios(struct tty_struct *tty, struct ktermios * old);
-static void micvcons_timeout(unsigned long);
+static void micvcons_timeout(struct timer_list *);
 static void micvcons_throttle(struct tty_struct *tty);
 static void micvcons_unthrottle(struct tty_struct *tty);
 static void micvcons_wakeup_readbuf(struct work_struct *work);
@@ -62,10 +62,19 @@ static struct tty_operations micvcons_tty_ops = {
 static struct tty_driver *micvcons_tty = NULL;
 static u16 extra_timeout = 0;
 static u8 restart_timer_flag = MICVCONS_TIMER_RESTART;
-static struct timer_list vcons_timer;
-static struct list_head timer_list_head;
 static spinlock_t timer_list_lock;
 
+// The timer API introduced in Linux 4.14.0 includes a from_timer() macro built
+// atop the container_of() macro. As the kernel moves away from using
+// timer_list.data, it quasi-assumes that the timer_list struct will be
+// contained in some larger struct that also contains the data, hence this
+// timer_wrapper struct since it allows us to avoid any serious code changes to
+// the driver.
+static struct timer_wrapper {
+	struct timer_list vcons_timer;
+	struct list_head timer_list_head;
+} timer_wrapper ;
+
 int
 micvcons_create(int num_bds)
 {
@@ -75,7 +84,7 @@ micvcons_create(int num_bds)
 	char wq_name[14];
 	struct device *dev;
 
-	INIT_LIST_HEAD(&timer_list_head);
+	INIT_LIST_HEAD(&timer_wrapper.timer_list_head);
 
 	if (micvcons_tty)
 		goto exit;
@@ -145,9 +154,7 @@ micvcons_create(int num_bds)
 		}
 		INIT_WORK(&port->dp_wakeup_read_buf, micvcons_wakeup_readbuf);
 	}
-	vcons_timer.function = micvcons_timeout;
-	vcons_timer.data = (unsigned long)(&timer_list_head);
-	init_timer(&vcons_timer);
+	timer_setup(&timer_wrapper.vcons_timer, micvcons_timeout, 0);
 exit:
 	return ret;
 }
@@ -215,10 +222,10 @@ micvcons_open(struct tty_struct * tty, struct file * filp)
 		if (ret != 0)
 			goto exit_locked;
 		spin_lock(&timer_list_lock);
-		list_add_tail_rcu(&port->list_member, &timer_list_head);
-		if (list_is_singular(&timer_list_head)) {
+		list_add_tail_rcu(&port->list_member, &timer_wrapper.timer_list_head);
+		if (list_is_singular(&timer_wrapper.timer_list_head)) {
 			restart_timer_flag = MICVCONS_TIMER_RESTART;
-			mod_timer(&vcons_timer, jiffies + 
+			mod_timer(&timer_wrapper.vcons_timer, jiffies +
 				msecs_to_jiffies(MICVCONS_SHORT_TIMEOUT));
 		}
 		spin_unlock(&timer_list_lock);
@@ -235,10 +242,10 @@ micvcons_del_timer_entry(micvcons_port_t *port)
 {
 	spin_lock(&timer_list_lock);
 	list_del_rcu(&port->list_member);
-	if (list_empty(&timer_list_head)) {
+	if (list_empty(&timer_wrapper.timer_list_head)) {
 		restart_timer_flag = MICVCONS_TIMER_SHUTDOWN;
 		spin_unlock(&timer_list_lock);
-		del_timer_sync(&vcons_timer);
+		del_timer_sync(&timer_wrapper.vcons_timer);
 	} else {
 		spin_unlock(&timer_list_lock);
 	}
@@ -499,9 +506,10 @@ micvcons_wakeup_readbuf(struct work_struct *work)
 }
 
 static void
-micvcons_timeout(unsigned long data)
+micvcons_timeout(struct timer_list *t)
 {
-	struct list_head *timer_list_ptr = (struct list_head *)data;
+	struct timer_wrapper *tm_wrap = from_timer(tm_wrap, t, vcons_timer);
+	struct list_head *timer_list_ptr = &tm_wrap->timer_list_head;
 	micvcons_port_t *port;
 	u8 console_active = 0;
 	int num_chars_read = 0;
@@ -519,7 +527,7 @@ micvcons_timeout(unsigned long data)
 		extra_timeout = (console_active ? 0 :
 				extra_timeout + MICVCONS_SHORT_TIMEOUT);
 		extra_timeout = min(extra_timeout, (u16)MICVCONS_MAX_TIMEOUT);
-		mod_timer(&vcons_timer, jiffies + 
+		mod_timer(&timer_wrapper.vcons_timer, jiffies +
 			msecs_to_jiffies(MICVCONS_SHORT_TIMEOUT+extra_timeout));
 	}
 	spin_unlock(&timer_list_lock);