hvc_console: Add support for tty window resizing
The patch provides the hvc_resize() function to update the terminal
window dimensions (struct winsize) for a specified hvc console.
The function stores the new window size and schedules a function
that finally updates the tty winsize and signals the change to
user space (SIGWINCH).
Because the winsize update must acquire a mutex and might sleep,
the function is scheduled instead of being called from hvc_poll()
or khvcd.
This patch uses the tty_do_resize() routine from the tty layer.
A pending resize work is canceled in hvc_close() and hvc_hangup().
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index 3650c90..2d256dc 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -374,6 +374,9 @@
if (hp->ops->notifier_del)
hp->ops->notifier_del(hp, hp->data);
+ /* cancel pending tty resize work */
+ cancel_work_sync(&hp->tty_resize);
+
/*
* Chain calls chars_in_buffer() and returns immediately if
* there is no buffered data otherwise sleeps on a wait queue
@@ -399,6 +402,9 @@
if (!hp)
return;
+ /* cancel pending tty resize work */
+ cancel_work_sync(&hp->tty_resize);
+
spin_lock_irqsave(&hp->lock, flags);
/*
@@ -494,6 +500,39 @@
return written;
}
+/**
+ * hvc_set_winsz() - Resize the hvc tty terminal window.
+ * @work: work structure.
+ *
+ * The routine shall not be called within an atomic context because it
+ * might sleep.
+ *
+ * Locking: hp->lock
+ */
+static void hvc_set_winsz(struct work_struct *work)
+{
+ struct hvc_struct *hp;
+ unsigned long hvc_flags;
+ struct tty_struct *tty;
+ struct winsize ws;
+
+ hp = container_of(work, struct hvc_struct, tty_resize);
+ if (!hp)
+ return;
+
+ spin_lock_irqsave(&hp->lock, hvc_flags);
+ if (!hp->tty) {
+ spin_unlock_irqrestore(&hp->lock, hvc_flags);
+ return;
+ }
+ ws = hp->ws;
+ tty = tty_kref_get(hp->tty);
+ spin_unlock_irqrestore(&hp->lock, hvc_flags);
+
+ tty_do_resize(tty, tty, &ws);
+ tty_kref_put(tty);
+}
+
/*
* This is actually a contract between the driver and the tty layer outlining
* how much write room the driver can guarantee will be sent OR BUFFERED. This
@@ -638,6 +677,24 @@
}
EXPORT_SYMBOL_GPL(hvc_poll);
+/**
+ * hvc_resize() - Update terminal window size information.
+ * @hp: HVC console pointer
+ * @ws: Terminal window size structure
+ *
+ * Stores the specified window size information in the hvc structure of @hp.
+ * The function schedule the tty resize update.
+ *
+ * Locking: Locking free; the function MUST be called holding hp->lock
+ */
+void hvc_resize(struct hvc_struct *hp, struct winsize ws)
+{
+ if ((hp->ws.ws_row != ws.ws_row) || (hp->ws.ws_col != ws.ws_col)) {
+ hp->ws = ws;
+ schedule_work(&hp->tty_resize);
+ }
+}
+
/*
* This kthread is either polling or interrupt driven. This is determined by
* calling hvc_poll() who determines whether a console adapter support
@@ -720,6 +777,7 @@
kref_init(&hp->kref);
+ INIT_WORK(&hp->tty_resize, hvc_set_winsz);
spin_lock_init(&hp->lock);
spin_lock(&hvc_structs_lock);