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Subject[PATCH 1/3] vgacon: Fix & cleanup refcounting
Date
The vgacon driver prepares a two element array of uni_pagedir_loc and
uses the second item as its own reference counter for sharing the
uni_pagedir. And the code assumes blindly that the second item is
available if the assigned vc_uni_pagedir isn't the standard one, which
might be wrong (although currently it's so).

This patch fixes that wrong assumption, and gives a slight cleanup
along with it: namely, instead of array, just give the uni_pagedir_loc
and a separate refcount variable. It makes the code a bit more
understandable at first glance.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
drivers/video/console/vgacon.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 9d8feac67637..9e18770aaba6 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -87,7 +87,8 @@ static void vgacon_save_screen(struct vc_data *c);
static int vgacon_scroll(struct vc_data *c, int t, int b, int dir,
int lines);
static void vgacon_invert_region(struct vc_data *c, u16 * p, int count);
-static unsigned long vgacon_uni_pagedir[2];
+static unsigned long vgacon_uni_pagedir;
+static int vgacon_refcount;

/* Description of the hardware situation */
static int vga_init_done __read_mostly;
@@ -575,12 +576,12 @@ static void vgacon_init(struct vc_data *c, int init)
if (vga_512_chars)
c->vc_hi_font_mask = 0x0800;
p = *c->vc_uni_pagedir_loc;
- if (c->vc_uni_pagedir_loc == &c->vc_uni_pagedir ||
- !--c->vc_uni_pagedir_loc[1])
+ if (c->vc_uni_pagedir_loc != &vgacon_uni_pagedir) {
con_free_unimap(c);
- c->vc_uni_pagedir_loc = vgacon_uni_pagedir;
- vgacon_uni_pagedir[1]++;
- if (!vgacon_uni_pagedir[0] && p)
+ c->vc_uni_pagedir_loc = &vgacon_uni_pagedir;
+ vgacon_refcount++;
+ }
+ if (!vgacon_uni_pagedir && p)
con_set_default_unimap(c);

/* Only set the default if the user didn't deliberately override it */
@@ -597,7 +598,7 @@ static void vgacon_deinit(struct vc_data *c)
vga_set_mem_top(c);
}

- if (!--vgacon_uni_pagedir[1])
+ if (!--vgacon_refcount)
con_free_unimap(c);
c->vc_uni_pagedir_loc = &c->vc_uni_pagedir;
con_set_default_unimap(c);
--
1.9.2


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