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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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Hendrik Brueckner 2008-10-14 05:02:09 +00:00 committed by Benjamin Herrenschmidt
parent 3feebbb549
commit febde37119
2 changed files with 64 additions and 0 deletions
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58
drivers/char/hvc_console.c
View File

@ -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);

6
drivers/char/hvc_console.h
View File

@ -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);