[PATCH] Video: fb, add true ref_count atomicity

[linux-drm-fsl-dcu.git] / drivers / video / vga16fb.c

diff --git a/drivers/video/vga16fb.c b/drivers/video/vga16fb.c
index 6aff63d5b295f97211a88ef84243f16613d4c7a1..ec4c7dc54a66972dbc662e0137b468d2bda088aa 100644 (file)
--- 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;