[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>
diff --git a/drivers/video/i810/i810.h b/drivers/video/i810/i810.h
index 579195c..aa65ffc 100644
--- a/drivers/video/i810/i810.h
+++ b/drivers/video/i810/i810.h
@@ -264,7 +264,8 @@
struct heap_data cursor_heap;
struct vgastate state;
struct i810fb_i2c_chan chan[3];
- atomic_t use_count;
+ struct mutex open_lock;
+ unsigned int use_count;
u32 pseudo_palette[17];
unsigned long mmio_start_phys;
u8 __iomem *mmio_start_virtual;
diff --git a/drivers/video/i810/i810_main.c b/drivers/video/i810/i810_main.c
index b55a12d..e343c0d 100644
--- a/drivers/video/i810/i810_main.c
+++ b/drivers/video/i810/i810_main.c
@@ -1235,9 +1235,9 @@
static int i810fb_open(struct fb_info *info, int user)
{
struct i810fb_par *par = info->par;
- u32 count = atomic_read(&par->use_count);
-
- if (count == 0) {
+
+ mutex_lock(&par->open_lock);
+ if (par->use_count == 0) {
memset(&par->state, 0, sizeof(struct vgastate));
par->state.flags = VGA_SAVE_CMAP;
par->state.vgabase = par->mmio_start_virtual;
@@ -1246,7 +1246,8 @@
i810_save_vga_state(par);
}
- atomic_inc(&par->use_count);
+ par->use_count++;
+ mutex_unlock(&par->open_lock);
return 0;
}
@@ -1254,18 +1255,20 @@
static int i810fb_release(struct fb_info *info, int user)
{
struct i810fb_par *par = info->par;
- u32 count;
-
- count = atomic_read(&par->use_count);
- if (count == 0)
- return -EINVAL;
- if (count == 1) {
+ mutex_lock(&par->open_lock);
+ if (par->use_count == 0) {
+ mutex_unlock(&par->open_lock);
+ return -EINVAL;
+ }
+
+ if (par->use_count == 1) {
i810_restore_vga_state(par);
restore_vga(&par->state);
}
- atomic_dec(&par->use_count);
+ par->use_count--;
+ mutex_unlock(&par->open_lock);
return 0;
}
@@ -1752,6 +1755,8 @@
static void __devinit i810_init_defaults(struct i810fb_par *par,
struct fb_info *info)
{
+ mutex_init(&par->open_lock);
+
if (voffset)
v_offset_default = voffset;
else if (par->aperture.size > 32 * 1024 * 1024)
diff --git a/drivers/video/neofb.c b/drivers/video/neofb.c
index 459ca55..395cced 100644
--- a/drivers/video/neofb.c
+++ b/drivers/video/neofb.c
@@ -556,14 +556,16 @@
neofb_open(struct fb_info *info, int user)
{
struct neofb_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_MODE | VGA_SAVE_FONTS;
save_vga(&par->state);
}
- atomic_inc(&par->ref_count);
+ par->ref_count++;
+ mutex_unlock(&par->open_lock);
+
return 0;
}
@@ -571,14 +573,18 @@
neofb_release(struct fb_info *info, int user)
{
struct neofb_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;
}
@@ -2047,6 +2053,7 @@
info->fix.accel = id->driver_data;
+ mutex_init(&par->open_lock);
par->pci_burst = !nopciburst;
par->lcd_stretch = !nostretch;
par->libretto = libretto;
diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c
index 1a13966..7c19b5c2a 100644
--- a/drivers/video/riva/fbdev.c
+++ b/drivers/video/riva/fbdev.c
@@ -1101,10 +1101,10 @@
static int rivafb_open(struct fb_info *info, int user)
{
struct riva_par *par = info->par;
- int cnt = atomic_read(&par->ref_count);
NVTRACE_ENTER();
- if (!cnt) {
+ mutex_lock(&par->open_lock);
+ if (!par->ref_count) {
#ifdef CONFIG_X86
memset(&par->state, 0, sizeof(struct vgastate));
par->state.flags = VGA_SAVE_MODE | VGA_SAVE_FONTS;
@@ -1119,7 +1119,8 @@
riva_save_state(par, &par->initial_state);
}
- atomic_inc(&par->ref_count);
+ par->ref_count++;
+ mutex_unlock(&par->open_lock);
NVTRACE_LEAVE();
return 0;
}
@@ -1127,12 +1128,14 @@
static int rivafb_release(struct fb_info *info, int user)
{
struct riva_par *par = info->par;
- int cnt = atomic_read(&par->ref_count);
NVTRACE_ENTER();
- 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) {
par->riva.LockUnlock(&par->riva, 0);
par->riva.LoadStateExt(&par->riva, &par->initial_state.ext);
riva_load_state(par, &par->initial_state);
@@ -1141,7 +1144,8 @@
#endif
par->riva.LockUnlock(&par->riva, 1);
}
- atomic_dec(&par->ref_count);
+ par->ref_count--;
+ mutex_unlock(&par->open_lock);
NVTRACE_LEAVE();
return 0;
}
@@ -1999,6 +2003,7 @@
goto err_disable_device;
}
+ mutex_init(&default_par->open_lock);
default_par->riva.Architecture = riva_get_arch(pd);
default_par->Chipset = (pd->vendor << 16) | pd->device;
diff --git a/drivers/video/riva/rivafb.h b/drivers/video/riva/rivafb.h
index 7fa13fc..48ead6d 100644
--- a/drivers/video/riva/rivafb.h
+++ b/drivers/video/riva/rivafb.h
@@ -53,7 +53,8 @@
#ifdef CONFIG_X86
struct vgastate state;
#endif
- atomic_t ref_count;
+ struct mutex open_lock;
+ unsigned int ref_count;
unsigned char *EDID;
unsigned int Chipset;
int forceCRTC;
diff --git a/drivers/video/vga16fb.c b/drivers/video/vga16fb.c
index 6aff63d..ec4c7dc 100644
--- a/drivers/video/vga16fb.c
+++ b/drivers/video/vga16fb.c
@@ -70,7 +70,8 @@
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 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 @@
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;
diff --git a/include/video/neomagic.h b/include/video/neomagic.h
index 78b1f15..a9e118a 100644
--- a/include/video/neomagic.h
+++ b/include/video/neomagic.h
@@ -140,7 +140,8 @@
struct neofb_par {
struct vgastate state;
- atomic_t ref_count;
+ struct mutex open_lock;
+ unsigned int ref_count;
unsigned char MiscOutReg; /* Misc */
unsigned char CRTC[25]; /* Crtc Controller */