[PATCH] Module ref counting for vt console drivers

From: Herbert Xu
Date: Thu Apr 29 2004 - 06:51:21 EST

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Hi:

The following patch adds basic module reference counting to vt console
drivers. Currently modules like fbcon are not counted at all.

Cheers,
--
Debian GNU/Linux 3.0 is out! ( http://www.debian.org/ )
Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
Index: drivers/char/vt.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/char/vt.c,v
retrieving revision 1.6
diff -u -r1.6 vt.c
--- a/drivers/char/vt.c 5 Apr 2004 10:54:32 -0000 1.6
+++ b/drivers/char/vt.c 29 Apr 2004 11:30:11 -0000
@@ -661,11 +661,14 @@
static void visual_init(int currcons, int init)
{
/* ++Geert: sw->con_init determines console size */
+ if (sw)
+ module_put(sw->owner);
sw = conswitchp;
#ifndef VT_SINGLE_DRIVER
if (con_driver_map[currcons])
sw = con_driver_map[currcons];
#endif
+ __module_get(sw->owner);
cons_num = currcons;
display_fg = &master_display_fg;
vc_cons[currcons].d->vc_uni_pagedir_loc = &vc_cons[currcons].d->vc_uni_pagedir;
@@ -2653,25 +2656,38 @@
* and become default driver for newly opened ones.
*/

-void take_over_console(const struct consw *csw, int first, int last, int deflt)
+int take_over_console(const struct consw *csw, int first, int last, int deflt)
{
int i, j = -1;
const char *desc;
+ struct module *owner;
+
+ owner = csw->owner;
+ if (!try_module_get(owner))
+ return -ENODEV;

acquire_console_sem();

desc = csw->con_startup();
if (!desc) {
release_console_sem();
- return;
+ module_put(owner);
+ return -ENODEV;
}
- if (deflt)
+ if (deflt) {
+ if (conswitchp)
+ module_put(conswitchp->owner);
+ __module_get(owner);
conswitchp = csw;
+ }

for (i = first; i <= last; i++) {
int old_was_color;
int currcons = i;

+ if (con_driver_map[i])
+ module_put(con_driver_map[i]->owner);
+ __module_get(owner);
con_driver_map[i] = csw;

if (!vc_cons[i].d || !vc_cons[i].d->vc_sw)
@@ -2706,6 +2722,9 @@
printk("to %s\n", desc);

release_console_sem();
+
+ module_put(owner);
+ return 0;
}

void give_up_console(const struct consw *csw)
@@ -2713,8 +2732,10 @@
int i;

for(i = 0; i < MAX_NR_CONSOLES; i++)
- if (con_driver_map[i] == csw)
+ if (con_driver_map[i] == csw) {
+ module_put(csw->owner);
con_driver_map[i] = NULL;
+ }
}

#endif
Index: drivers/video/console/dummycon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/dummycon.c,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 dummycon.c
--- a/drivers/video/console/dummycon.c 3 Jan 2003 01:36:55 -0000 1.1.1.2
+++ b/drivers/video/console/dummycon.c 29 Apr 2004 10:58:51 -0000
@@ -11,6 +11,7 @@
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/init.h>
+#include <linux/module.h>

/*
* Dummy console driver
@@ -58,6 +59,7 @@
*/

const struct consw dummy_con = {
+ .owner = THIS_MODULE,
.con_startup = dummycon_startup,
.con_init = dummycon_init,
.con_deinit = DUMMY,
Index: drivers/video/console/fbcon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/fbcon.c,v
retrieving revision 1.1.1.10
diff -u -r1.1.1.10 fbcon.c
--- a/drivers/video/console/fbcon.c 5 Apr 2004 09:49:37 -0000 1.1.1.10
+++ b/drivers/video/console/fbcon.c 29 Apr 2004 11:12:28 -0000
@@ -304,8 +304,7 @@
return -ENODEV;
con2fb_map[unit] = newidx;
fbcon_is_default = (vc->vc_sw == &fb_con) ? 1 : 0;
- take_over_console(&fb_con, unit, unit, fbcon_is_default);
- return 0;
+ return take_over_console(&fb_con, unit, unit, fbcon_is_default);
}

/*
@@ -2257,6 +2256,7 @@
*/

const struct consw fb_con = {
+ .owner = THIS_MODULE,
.con_startup = fbcon_startup,
.con_init = fbcon_init,
.con_deinit = fbcon_deinit,
@@ -2286,10 +2286,16 @@

int __init fb_console_init(void)
{
+ int err;
+
if (!num_registered_fb)
return -ENODEV;

- take_over_console(&fb_con, first_fb_vc, last_fb_vc, fbcon_is_default);
+ err = take_over_console(&fb_con, first_fb_vc, last_fb_vc,
+ fbcon_is_default);
+ if (err)
+ return err;
+
acquire_console_sem();
if (!fbcon_event_notifier_registered) {
fb_register_client(&fbcon_event_notifer);
Index: drivers/video/console/mdacon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/mdacon.c,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 mdacon.c
--- a/drivers/video/console/mdacon.c 3 Jan 2003 01:36:55 -0000 1.1.1.2
+++ b/drivers/video/console/mdacon.c 29 Apr 2004 11:17:39 -0000
@@ -370,8 +370,6 @@

if (mda_display_fg == NULL)
mda_display_fg = c;
-
- MOD_INC_USE_COUNT;
}

static void mdacon_deinit(struct vc_data *c)
@@ -380,8 +378,6 @@

if (mda_display_fg == c)
mda_display_fg = NULL;
-
- MOD_DEC_USE_COUNT;
}

static inline u16 mda_convert_attr(u16 ch)
@@ -586,6 +582,7 @@
*/

const struct consw mda_con = {
+ .owner = THIS_MODULE,
.con_startup = mdacon_startup,
.con_init = mdacon_init,
.con_deinit = mdacon_deinit,
@@ -609,8 +606,7 @@
if (mda_first_vc > mda_last_vc)
return 1;

- take_over_console(&mda_con, mda_first_vc-1, mda_last_vc-1, 0);
- return 0;
+ return take_over_console(&mda_con, mda_first_vc-1, mda_last_vc-1, 0);
}

void __exit mda_console_exit(void)
Index: drivers/video/console/newport_con.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/newport_con.c,v
retrieving revision 1.1.1.3
diff -u -r1.1.1.3 newport_con.c
--- a/drivers/video/console/newport_con.c 24 Mar 2003 22:01:16 -0000 1.1.1.3
+++ b/drivers/video/console/newport_con.c 29 Apr 2004 11:12:38 -0000
@@ -677,6 +677,7 @@
#define DUMMY (void *) newport_dummy

const struct consw newport_con = {
+ .owner = THIS_MODULE,
.con_startup = newport_startup,
.con_init = newport_init,
.con_deinit = DUMMY,
@@ -704,9 +705,7 @@
printk("Error loading SGI Newport Console driver\n");
else
printk("Loading SGI Newport Console Driver\n");
- take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
-
- return 0;
+ return take_over_console(&newport_con, 0, MAX_NR_CONSOLES - 1, 1);
}

int cleanup_module(void)
Index: drivers/video/console/promcon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/promcon.c,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 promcon.c
--- a/drivers/video/console/promcon.c 11 Mar 2004 02:55:33 -0000 1.1.1.2
+++ b/drivers/video/console/promcon.c 29 Apr 2004 10:59:56 -0000
@@ -574,6 +574,7 @@
#define DUMMY (void *) promcon_dummy

const struct consw prom_con = {
+ .owner = THIS_MODULE,
.con_startup = promcon_startup,
.con_init = promcon_init,
.con_deinit = promcon_deinit,
Index: drivers/video/console/sticon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/sticon.c,v
retrieving revision 1.1.1.4
diff -u -r1.1.1.4 sticon.c
--- a/drivers/video/console/sticon.c 11 Mar 2004 02:55:37 -0000 1.1.1.4
+++ b/drivers/video/console/sticon.c 29 Apr 2004 11:13:13 -0000
@@ -354,6 +354,7 @@
}

static struct consw sti_con = {
+ .owner = THIS_MODULE,
.con_startup = sticon_startup,
.con_init = sticon_init,
.con_deinit = sticon_deinit,
@@ -390,7 +391,7 @@

if (conswitchp == &dummy_con) {
printk(KERN_INFO "sticon: Initializing STI text console.\n");
- take_over_console(&sti_con, 0, MAX_NR_CONSOLES - 1, 1);
+ return take_over_console(&sti_con, 0, MAX_NR_CONSOLES - 1, 1);
}
return 0;
}
Index: drivers/video/console/vgacon.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/drivers/video/console/vgacon.c,v
retrieving revision 1.1.1.3
diff -u -r1.1.1.3 vgacon.c
--- a/drivers/video/console/vgacon.c 11 Mar 2004 02:55:26 -0000 1.1.1.3
+++ b/drivers/video/console/vgacon.c 29 Apr 2004 11:00:24 -0000
@@ -1065,6 +1065,7 @@
#define DUMMY (void *) vgacon_dummy

const struct consw vga_con = {
+ .owner = THIS_MODULE,
.con_startup = vgacon_startup,
.con_init = vgacon_init,
.con_deinit = vgacon_deinit,
Index: include/linux/console.h
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/include/linux/console.h,v
retrieving revision 1.1.1.8
diff -u -r1.1.1.8 console.h
--- a/include/linux/console.h 11 Mar 2004 02:55:26 -0000 1.1.1.8
+++ b/include/linux/console.h 29 Apr 2004 10:47:39 -0000
@@ -19,6 +19,7 @@

struct vc_data;
struct console_font_op;
+struct module;

/*
* this is what the terminal answers to a ESC-Z or csi0c query.
@@ -27,6 +28,7 @@
#define VT102ID "\033[?6c"

struct consw {
+ struct module *owner;
const char *(*con_startup)(void);
void (*con_init)(struct vc_data *, int);
void (*con_deinit)(struct vc_data *);
@@ -58,7 +60,7 @@
extern const struct consw newport_con; /* SGI Newport console */
extern const struct consw prom_con; /* SPARC PROM console */

-void take_over_console(const struct consw *sw, int first, int last, int deflt);
+int take_over_console(const struct consw *sw, int first, int last, int deflt);
void give_up_console(const struct consw *sw);

/* scroll */

Next message: Maciej W. Rozycki: "Re: IO-APIC on nforce2 [PATCH] + [PATCH] for nmi_debug=1 + [PATCH]for idle=C1halt, 2.6.5"
Previous message: Ross Dickson: "Re: IO-APIC on nforce2 [PATCH] + [PATCH] for nmi_debug=1 + [PATCH] for idle=C1halt, 2.6.5"
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