OMAP: DSS2: OMAPFB: Make lockdep happy

When more than one memory region needs to be lockd at the same time use
the memory region id to fix the order in which the locks are taken. Also
one needs to use the _nested() versions of the locking primitives. The
memory region id can serve as the lock class there as well.

Signed-off-by: Ville Syrjälä <ville.syrjala@nokia.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@nokia.com>

diff --git a/drivers/video/omap2/omapfb/omapfb-ioctl.c b/drivers/video/omap2/omapfb/omapfb-ioctl.c
index 3a10146dc1208c5e4f754e47d143279269a72a9c..7975a99c33f9c35a190c9fe6b002f25ffe09050f 100644 (file)
--- a/drivers/video/omap2/omapfb/omapfb-ioctl.c
+++ b/drivers/video/omap2/omapfb/omapfb-ioctl.c
@@ -55,7 +55,7 @@ static struct omapfb2_mem_region *get_mem_region(struct omapfb_info *ofbi,
        if (mem_idx >= fbdev->num_fbs)
                return NULL;
 
-       return omapfb_get_mem_region(&fbdev->regions[mem_idx]);
+       return &fbdev->regions[mem_idx];
 }
 
 static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
@@ -77,20 +77,30 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
        /* XXX uses only the first overlay */
        ovl = ofbi->overlays[0];
 
-       old_rg = omapfb_get_mem_region(ofbi->region);
+       old_rg = ofbi->region;
        new_rg = get_mem_region(ofbi, pi->mem_idx);
        if (!new_rg) {
                r = -EINVAL;
-               goto put_old;
+               goto out;
        }
 
+       /* Take the locks in a specific order to keep lockdep happy */
+       if (old_rg->id < new_rg->id) {
+               omapfb_get_mem_region(old_rg);
+               omapfb_get_mem_region(new_rg);
+       } else if (new_rg->id < old_rg->id) {
+               omapfb_get_mem_region(new_rg);
+               omapfb_get_mem_region(old_rg);
+       } else
+               omapfb_get_mem_region(old_rg);
+
        if (pi->enabled && !new_rg->size) {
                /*
                 * This plane's memory was freed, can't enable it
                 * until it's reallocated.
                 */
                r = -EINVAL;
-               goto put_new;
+               goto put_mem;
        }
 
        ovl->get_overlay_info(ovl, &old_info);
@@ -135,8 +145,15 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
        if (ovl->manager)
                ovl->manager->apply(ovl->manager);
 
-       omapfb_put_mem_region(new_rg);
-       omapfb_put_mem_region(old_rg);
+       /* Release the locks in a specific order to keep lockdep happy */
+       if (old_rg->id > new_rg->id) {
+               omapfb_put_mem_region(old_rg);
+               omapfb_put_mem_region(new_rg);
+       } else if (new_rg->id > old_rg->id) {
+               omapfb_put_mem_region(new_rg);
+               omapfb_put_mem_region(old_rg);
+       } else
+               omapfb_put_mem_region(old_rg);
 
        return 0;
 
@@ -147,10 +164,16 @@ static int omapfb_setup_plane(struct fb_info *fbi, struct omapfb_plane_info *pi)
        }
 
        ovl->set_overlay_info(ovl, &old_info);
- put_new:
-       omapfb_put_mem_region(new_rg);
- put_old:
-       omapfb_put_mem_region(old_rg);
+ put_mem:
+       /* Release the locks in a specific order to keep lockdep happy */
+       if (old_rg->id > new_rg->id) {
+               omapfb_put_mem_region(old_rg);
+               omapfb_put_mem_region(new_rg);
+       } else if (new_rg->id > old_rg->id) {
+               omapfb_put_mem_region(new_rg);
+               omapfb_put_mem_region(old_rg);
+       } else
+               omapfb_put_mem_region(old_rg);
  out:
        dev_err(fbdev->dev, "setup_plane failed\n");
 
@@ -198,7 +221,7 @@ static int omapfb_setup_mem(struct fb_info *fbi, struct omapfb_mem_info *mi)
 
        rg = ofbi->region;
 
-       down_write(&rg->lock);
+       down_write_nested(&rg->lock, rg->id);
 
        if (atomic_read(&rg->map_count)) {
                r = -EBUSY;

diff --git a/drivers/video/omap2/omapfb/omapfb-sysfs.c b/drivers/video/omap2/omapfb/omapfb-sysfs.c
index 724b760404f2ddffe8e3b2f084ff0116b3e47e02..1e714bb48d3935e4f11188824e8c57635b679ec6 100644 (file)
--- a/drivers/video/omap2/omapfb/omapfb-sysfs.c
+++ b/drivers/video/omap2/omapfb/omapfb-sysfs.c
@@ -452,7 +452,7 @@ static ssize_t store_size(struct device *dev, struct device_attribute *attr,
 
        rg = ofbi->region;
 
-       down_write(&rg->lock);
+       down_write_nested(&rg->lock, rg->id);
 
        if (atomic_read(&rg->map_count)) {
                r = -EBUSY;

diff --git a/drivers/video/omap2/omapfb/omapfb.h b/drivers/video/omap2/omapfb/omapfb.h
index 195a760eef542b4adcd30a2678c5fc9fe7273a69..676b55d9894180601a11d3a67144f464e90f23e5 100644 (file)
--- a/drivers/video/omap2/omapfb/omapfb.h
+++ b/drivers/video/omap2/omapfb/omapfb.h
@@ -165,7 +165,7 @@ static inline int omapfb_overlay_enable(struct omap_overlay *ovl,
 static inline struct omapfb2_mem_region *
 omapfb_get_mem_region(struct omapfb2_mem_region *rg)
 {
-       down_read(&rg->lock);
+       down_read_nested(&rg->lock, rg->id);
        return rg;
 }