[PATCH] fbdev: Reduce stack usage

calc_mode_timings() and fb_get_mode() are using more than 500 bytes off the
stack.  Fix.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/video/fbmon.c b/drivers/video/fbmon.c
index fc7965b66775983a97d62d10ab7805c475e0eb73..0ef75a9f84affb10277d283f1d3d4573f513f262 100644 (file)
--- a/drivers/video/fbmon.c
+++ b/drivers/video/fbmon.c
@@ -317,26 +317,29 @@ static int edid_is_monitor_block(unsigned char *block)
 static void calc_mode_timings(int xres, int yres, int refresh,
                              struct fb_videomode *mode)
 {
-       struct fb_var_screeninfo var;
-       struct fb_info info;
+       struct fb_var_screeninfo *var;
        
-       memset(&var, 0, sizeof(struct fb_var_screeninfo));
-       var.xres = xres;
-       var.yres = yres;
-       fb_get_mode(FB_VSYNCTIMINGS | FB_IGNOREMON, 
-                   refresh, &var, &info);
-       mode->xres = xres;
-       mode->yres = yres;
-       mode->pixclock = var.pixclock;
-       mode->refresh = refresh;
-       mode->left_margin = var.left_margin;
-       mode->right_margin = var.right_margin;
-       mode->upper_margin = var.upper_margin;
-       mode->lower_margin = var.lower_margin;
-       mode->hsync_len = var.hsync_len;
-       mode->vsync_len = var.vsync_len;
-       mode->vmode = 0;
-       mode->sync = 0;
+       var = kzalloc(sizeof(struct fb_var_screeninfo), GFP_KERNEL);
+
+       if (var) {
+               var->xres = xres;
+               var->yres = yres;
+               fb_get_mode(FB_VSYNCTIMINGS | FB_IGNOREMON,
+                           refresh, var, NULL);
+               mode->xres = xres;
+               mode->yres = yres;
+               mode->pixclock = var->pixclock;
+               mode->refresh = refresh;
+               mode->left_margin = var->left_margin;
+               mode->right_margin = var->right_margin;
+               mode->upper_margin = var->upper_margin;
+               mode->lower_margin = var->lower_margin;
+               mode->hsync_len = var->hsync_len;
+               mode->vsync_len = var->vsync_len;
+               mode->vmode = 0;
+               mode->sync = 0;
+               kfree(var);
+       }
 }
 
 static int get_est_timing(unsigned char *block, struct fb_videomode *mode)
@@ -1105,15 +1108,21 @@ static void fb_timings_dclk(struct __fb_timings *timings)
  */ 
 int fb_get_mode(int flags, u32 val, struct fb_var_screeninfo *var, struct fb_info *info)
 {
-       struct __fb_timings timings;
+       struct __fb_timings *timings;
        u32 interlace = 1, dscan = 1;
-       u32 hfmin, hfmax, vfmin, vfmax, dclkmin, dclkmax;
+       u32 hfmin, hfmax, vfmin, vfmax, dclkmin, dclkmax, err = 0;
+
+
+       timings = kzalloc(sizeof(struct __fb_timings), GFP_KERNEL);
+
+       if (!timings)
+               return -ENOMEM;
 
        /* 
         * If monspecs are invalid, use values that are enough
         * for 640x480@60
         */
-       if (!info->monspecs.hfmax || !info->monspecs.vfmax ||
+       if (!info || !info->monspecs.hfmax || !info->monspecs.vfmax ||
            !info->monspecs.dclkmax ||
            info->monspecs.hfmax < info->monspecs.hfmin ||
            info->monspecs.vfmax < info->monspecs.vfmin ||
@@ -1130,65 +1139,66 @@ int fb_get_mode(int flags, u32 val, struct fb_var_screeninfo *var, struct fb_inf
                dclkmax = info->monspecs.dclkmax;
        }
 
-       memset(&timings, 0, sizeof(struct __fb_timings));
-       timings.hactive = var->xres;
-       timings.vactive = var->yres;
+       timings->hactive = var->xres;
+       timings->vactive = var->yres;
        if (var->vmode & FB_VMODE_INTERLACED) { 
-               timings.vactive /= 2;
+               timings->vactive /= 2;
                interlace = 2;
        }
        if (var->vmode & FB_VMODE_DOUBLE) {
-               timings.vactive *= 2;
+               timings->vactive *= 2;
                dscan = 2;
        }
 
        switch (flags & ~FB_IGNOREMON) {
        case FB_MAXTIMINGS: /* maximize refresh rate */
-               timings.hfreq = hfmax;
-               fb_timings_hfreq(&timings);
-               if (timings.vfreq > vfmax) {
-                       timings.vfreq = vfmax;
-                       fb_timings_vfreq(&timings);
+               timings->hfreq = hfmax;
+               fb_timings_hfreq(timings);
+               if (timings->vfreq > vfmax) {
+                       timings->vfreq = vfmax;
+                       fb_timings_vfreq(timings);
                }
-               if (timings.dclk > dclkmax) {
-                       timings.dclk = dclkmax;
-                       fb_timings_dclk(&timings);
+               if (timings->dclk > dclkmax) {
+                       timings->dclk = dclkmax;
+                       fb_timings_dclk(timings);
                }
                break;
        case FB_VSYNCTIMINGS: /* vrefresh driven */
-               timings.vfreq = val;
-               fb_timings_vfreq(&timings);
+               timings->vfreq = val;
+               fb_timings_vfreq(timings);
                break;
        case FB_HSYNCTIMINGS: /* hsync driven */
-               timings.hfreq = val;
-               fb_timings_hfreq(&timings);
+               timings->hfreq = val;
+               fb_timings_hfreq(timings);
                break;
        case FB_DCLKTIMINGS: /* pixelclock driven */
-               timings.dclk = PICOS2KHZ(val) * 1000;
-               fb_timings_dclk(&timings);
+               timings->dclk = PICOS2KHZ(val) * 1000;
+               fb_timings_dclk(timings);
                break;
        default:
-               return -EINVAL;
+               err = -EINVAL;
                
        } 
        
-       if (!(flags & FB_IGNOREMON) && 
-           (timings.vfreq < vfmin || timings.vfreq > vfmax || 
-            timings.hfreq < hfmin || timings.hfreq > hfmax ||
-            timings.dclk < dclkmin || timings.dclk > dclkmax))
-               return -EINVAL;
-
-       var->pixclock = KHZ2PICOS(timings.dclk/1000);
-       var->hsync_len = (timings.htotal * 8)/100;
-       var->right_margin = (timings.hblank/2) - var->hsync_len;
-       var->left_margin = timings.hblank - var->right_margin - var->hsync_len;
-       
-       var->vsync_len = (3 * interlace)/dscan;
-       var->lower_margin = (1 * interlace)/dscan;
-       var->upper_margin = (timings.vblank * interlace)/dscan - 
-               (var->vsync_len + var->lower_margin);
+       if (err || (!(flags & FB_IGNOREMON) &&
+           (timings->vfreq < vfmin || timings->vfreq > vfmax ||
+            timings->hfreq < hfmin || timings->hfreq > hfmax ||
+            timings->dclk < dclkmin || timings->dclk > dclkmax))) {
+               err = -EINVAL;
+       } else {
+               var->pixclock = KHZ2PICOS(timings->dclk/1000);
+               var->hsync_len = (timings->htotal * 8)/100;
+               var->right_margin = (timings->hblank/2) - var->hsync_len;
+               var->left_margin = timings->hblank - var->right_margin -
+                       var->hsync_len;
+               var->vsync_len = (3 * interlace)/dscan;
+               var->lower_margin = (1 * interlace)/dscan;
+               var->upper_margin = (timings->vblank * interlace)/dscan -
+                       (var->vsync_len + var->lower_margin);
+       }
        
-       return 0;
+       kfree(timings);
+       return err;
 }
 #else
 int fb_parse_edid(unsigned char *edid, struct fb_var_screeninfo *var)