[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>

1 files changed, 68 insertions, 58 deletions

diff --git a/drivers/video/fbmon.c b/drivers/video/fbmon.c
index fc7965b66775..0ef75a9f84af 100644
--- 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)