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authorJiri Slaby <jirislaby@gmail.com>2007-02-12 00:55:11 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-12 09:48:42 -0800
commitc4f28e54d61278203c2bb2aea0679e0a738235d2 (patch)
treed92cf0718084a4e659444741443ee38afb847836 /drivers/video/vga16fb.c
parent52e7c922f37907ab3cf3445b916fbbc53cbd6c75 (diff)
[PATCH] Video: fb, add true ref_count atomicity
Some of fb drivers uses atomic_t in bad manner, since there are still some race-prone gaps. Use mutexes to protect open/close code sections with ref_count testing and finally use simple uint. Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Acked-by: Denis Oliver Kropp <dok@directfb.org> Cc: James Simmons <jsimmons@infradead.org> Cc: "Antonino A. Daplas" <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/video/vga16fb.c')
-rw-r--r--drivers/video/vga16fb.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/drivers/video/vga16fb.c b/drivers/video/vga16fb.c
index 6aff63d5b29..ec4c7dc54a6 100644
--- a/drivers/video/vga16fb.c
+++ b/drivers/video/vga16fb.c
@@ -70,7 +70,8 @@ struct vga16fb_par {
unsigned char ClockingMode; /* Seq-Controller:01h */
} vga_state;
struct vgastate state;
- atomic_t ref_count;
+ struct mutex open_lock;
+ unsigned int ref_count;
int palette_blanked, vesa_blanked, mode, isVGA;
u8 misc, pel_msk, vss, clkdiv;
u8 crtc[VGA_CRT_C];
@@ -300,28 +301,33 @@ static void vga16fb_clock_chip(struct vga16fb_par *par,
static int vga16fb_open(struct fb_info *info, int user)
{
struct vga16fb_par *par = info->par;
- int cnt = atomic_read(&par->ref_count);
- if (!cnt) {
+ mutex_lock(&par->open_lock);
+ if (!par->ref_count) {
memset(&par->state, 0, sizeof(struct vgastate));
par->state.flags = VGA_SAVE_FONTS | VGA_SAVE_MODE |
VGA_SAVE_CMAP;
save_vga(&par->state);
}
- atomic_inc(&par->ref_count);
+ par->ref_count++;
+ mutex_unlock(&par->open_lock);
+
return 0;
}
static int vga16fb_release(struct fb_info *info, int user)
{
struct vga16fb_par *par = info->par;
- int cnt = atomic_read(&par->ref_count);
- if (!cnt)
+ mutex_lock(&par->open_lock);
+ if (!par->ref_count) {
+ mutex_unlock(&par->open_lock);
return -EINVAL;
- if (cnt == 1)
+ }
+ if (par->ref_count == 1)
restore_vga(&par->state);
- atomic_dec(&par->ref_count);
+ par->ref_count--;
+ mutex_unlock(&par->open_lock);
return 0;
}
@@ -1357,6 +1363,7 @@ static int __init vga16fb_probe(struct platform_device *dev)
printk(KERN_INFO "vga16fb: mapped to 0x%p\n", info->screen_base);
par = info->par;
+ mutex_init(&par->open_lock);
par->isVGA = ORIG_VIDEO_ISVGA;
par->palette_blanked = 0;
par->vesa_blanked = 0;