drivers: staging: sm750: Hold lock irrespective of fb numbers.

Start holding the lock for all cases irrespective of number of fb,
there could be a deadlock since this number could change in the
lifetime of this lock
Signed-off-by: Dhananjay Balan <mail@dbalan.in>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sm750fb/sm750.c

@@ -183,10 +183,11 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
 	rop = (region->rop != ROP_COPY) ? HW_ROP2_XOR : HW_ROP2_COPY;
 
 	/*
-	 * If not use spin_lock,system will die if user load driver
+	 * If not use spin_lock, system will die if user load driver
 	 * and immediately unload driver frequently (dual)
+	 * since they fb_count could change during the lifetime of
+	 * this lock, we are holding it for all cases.
 	 */
-	if (sm750_dev->fb_count > 1)
 	spin_lock(&sm750_dev->slock);
 
 	sm750_dev->accel.de_fillrect(&sm750_dev->accel,
@@ -194,7 +195,6 @@ static void lynxfb_ops_fillrect(struct fb_info *info,
 				     region->dx, region->dy,
 				     region->width, region->height,
 				     color, rop);
-	if (sm750_dev->fb_count > 1)
 	spin_unlock(&sm750_dev->slock);
 }
 
@@ -219,8 +219,9 @@ static void lynxfb_ops_copyarea(struct fb_info *info,
 	/*
 	 * If not use spin_lock, system will die if user load driver
 	 * and immediately unload driver frequently (dual)
+	 * since they fb_count could change during the lifetime of
+	 * this lock, we are holding it for all cases.
 	 */
-	if (sm750_dev->fb_count > 1)
 	spin_lock(&sm750_dev->slock);
 
 	sm750_dev->accel.de_copyarea(&sm750_dev->accel,
@@ -228,7 +229,6 @@ static void lynxfb_ops_copyarea(struct fb_info *info,
 				     base, pitch, Bpp, region->dx, region->dy,
 				     region->width, region->height,
 				     HW_ROP2_COPY);
-	if (sm750_dev->fb_count > 1)
 	spin_unlock(&sm750_dev->slock);
 }
 
@@ -268,8 +268,9 @@ static void lynxfb_ops_imageblit(struct fb_info *info,
 	/*
 	 * If not use spin_lock, system will die if user load driver
 	 * and immediately unload driver frequently (dual)
+	 * since they fb_count could change during the lifetime of
+	 * this lock, we are holding it for all cases.
 	 */
-	if (sm750_dev->fb_count > 1)
 	spin_lock(&sm750_dev->slock);
 
 	sm750_dev->accel.de_imageblit(&sm750_dev->accel,
@@ -278,7 +279,6 @@ static void lynxfb_ops_imageblit(struct fb_info *info,
 				      image->dx, image->dy,
 				      image->width, image->height,
 				      fgcol, bgcol, HW_ROP2_COPY);
-	if (sm750_dev->fb_count > 1)
 	spin_unlock(&sm750_dev->slock);
 }