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Commit febde371 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Benjamin Herrenschmidt
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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: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 3feebbb5

drivers/char/hvc_console.c

+58 −0
Original line number Diff line number Diff line
@@ -374,6 +374,9 @@ static void hvc_close(struct tty_struct *tty, struct file * filp) 
		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 @@ static void hvc_hangup(struct tty_struct *tty) 
	if (!hp)

		return;



	/* cancel pending tty resize work */

	cancel_work_sync(&hp->tty_resize);



	spin_lock_irqsave(&hp->lock, flags);



	/*
@@ -494,6 +500,39 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count 
	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 @@ int hvc_poll(struct hvc_struct *hp) 
}

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 @@ struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int data, 


	kref_init(&hp->kref);



	INIT_WORK(&hp->tty_resize, hvc_set_winsz);

	spin_lock_init(&hp->lock);

	spin_lock(&hvc_structs_lock);

drivers/char/hvc_console.h

+6 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#ifndef HVC_CONSOLE_H

#define HVC_CONSOLE_H

#include <linux/kref.h>

#include <linux/tty.h>



/*

 * This is the max number of console adapters that can/will be found as
@@ -56,6 +57,8 @@ struct hvc_struct { 
	struct hv_ops *ops;

	int irq_requested;

	int data;

	struct winsize ws;

	struct work_struct tty_resize;

	struct list_head next;

	struct kref kref; /* ref count & hvc_struct lifetime */

};
@@ -84,6 +87,9 @@ extern int __devexit hvc_remove(struct hvc_struct *hp); 
int hvc_poll(struct hvc_struct *hp);

void hvc_kick(void);



/* Resize hvc tty terminal window */

extern void hvc_resize(struct hvc_struct *hp, struct winsize ws);



/* default notifier for irq based notification */

extern int notifier_add_irq(struct hvc_struct *hp, int data);

extern void notifier_del_irq(struct hvc_struct *hp, int data);