This patch resolves potential deadlock issue that can be incurred by changing file->f_op and filp->private_data to exynos specific mapper ops and gem object temporarily.
To resolve this issue, this patch creates a new anon file dedicated to exynos specific mmaper, and making it used instead of existing one.
Signed-off-by: Inki Dae inki.dae@samsung.com Signed-off-by: Kyungmin Park kyungmin.park@samsung.com --- drivers/gpu/drm/exynos/exynos_drm_drv.c | 21 +++++++++ drivers/gpu/drm/exynos/exynos_drm_drv.h | 1 + drivers/gpu/drm/exynos/exynos_drm_gem.c | 74 ++++++------------------------- drivers/gpu/drm/exynos/exynos_drm_gem.h | 3 ++ 4 files changed, 38 insertions(+), 61 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c index 22b8f5e..b5e5957 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c @@ -14,6 +14,8 @@ #include <drm/drmP.h> #include <drm/drm_crtc_helper.h>
+#include <linux/anon_inodes.h> + #include <drm/exynos_drm.h>
#include "exynos_drm_drv.h" @@ -150,9 +152,14 @@ static int exynos_drm_unload(struct drm_device *dev) return 0; }
+static const struct file_operations exynos_drm_gem_fops = { + .mmap = exynos_drm_gem_mmap_buffer, +}; + static int exynos_drm_open(struct drm_device *dev, struct drm_file *file) { struct drm_exynos_file_private *file_priv; + struct file *anon_filp; int ret;
file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL); @@ -167,6 +174,16 @@ static int exynos_drm_open(struct drm_device *dev, struct drm_file *file) file->driver_priv = NULL; }
+ anon_filp = anon_inode_getfile("exynos_gem", &exynos_drm_gem_fops, + NULL, 0); + if (IS_ERR(anon_filp)) { + kfree(file_priv); + return PTR_ERR(anon_filp); + } + + anon_filp->f_mode = FMODE_READ | FMODE_WRITE; + file_priv->anon_filp = anon_filp; + return ret; }
@@ -179,6 +196,7 @@ static void exynos_drm_preclose(struct drm_device *dev, static void exynos_drm_postclose(struct drm_device *dev, struct drm_file *file) { struct exynos_drm_private *private = dev->dev_private; + struct drm_exynos_file_private *file_priv; struct drm_pending_vblank_event *v, *vt; struct drm_pending_event *e, *et; unsigned long flags; @@ -204,6 +222,9 @@ static void exynos_drm_postclose(struct drm_device *dev, struct drm_file *file) } spin_unlock_irqrestore(&dev->event_lock, flags);
+ file_priv = file->driver_priv; + if (file_priv->anon_filp) + fput(file_priv->anon_filp);
kfree(file->driver_priv); file->driver_priv = NULL; diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.h b/drivers/gpu/drm/exynos/exynos_drm_drv.h index eaa1966..0eaf5a2 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_drv.h +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.h @@ -226,6 +226,7 @@ struct exynos_drm_ipp_private { struct drm_exynos_file_private { struct exynos_drm_g2d_private *g2d_priv; struct exynos_drm_ipp_private *ipp_priv; + struct file *anon_filp; };
/* diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c index 1ade191..49b8c9b 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_gem.c +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c @@ -338,46 +338,22 @@ int exynos_drm_gem_map_offset_ioctl(struct drm_device *dev, void *data, &args->offset); }
-static struct drm_file *exynos_drm_find_drm_file(struct drm_device *drm_dev, - struct file *filp) -{ - struct drm_file *file_priv; - - /* find current process's drm_file from filelist. */ - list_for_each_entry(file_priv, &drm_dev->filelist, lhead) - if (file_priv->filp == filp) - return file_priv; - - WARN_ON(1); - - return ERR_PTR(-EFAULT); -} - -static int exynos_drm_gem_mmap_buffer(struct file *filp, +int exynos_drm_gem_mmap_buffer(struct file *filp, struct vm_area_struct *vma) { struct drm_gem_object *obj = filp->private_data; struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj); struct drm_device *drm_dev = obj->dev; struct exynos_drm_gem_buf *buffer; - struct drm_file *file_priv; unsigned long vm_size; int ret;
+ WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); + vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP; vma->vm_private_data = obj; vma->vm_ops = drm_dev->driver->gem_vm_ops;
- /* restore it to driver's fops. */ - filp->f_op = fops_get(drm_dev->driver->fops); - - file_priv = exynos_drm_find_drm_file(drm_dev, filp); - if (IS_ERR(file_priv)) - return PTR_ERR(file_priv); - - /* restore it to drm_file. */ - filp->private_data = file_priv; - update_vm_cache_attr(exynos_gem_obj, vma);
vm_size = vma->vm_end - vma->vm_start; @@ -411,15 +387,13 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp, return 0; }
-static const struct file_operations exynos_drm_gem_fops = { - .mmap = exynos_drm_gem_mmap_buffer, -}; - int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { + struct drm_exynos_file_private *exynos_file_priv; struct drm_exynos_gem_mmap *args = data; struct drm_gem_object *obj; + struct file *anon_filp; unsigned long addr;
if (!(dev->driver->driver_features & DRIVER_GEM)) { @@ -427,47 +401,25 @@ int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data, return -ENODEV; }
+ mutex_lock(&dev->struct_mutex); + obj = drm_gem_object_lookup(dev, file_priv, args->handle); if (!obj) { DRM_ERROR("failed to lookup gem object.\n"); + mutex_unlock(&dev->struct_mutex); return -EINVAL; }
- /* - * We have to use gem object and its fops for specific mmaper, - * but vm_mmap() can deliver only filp. So we have to change - * filp->f_op and filp->private_data temporarily, then restore - * again. So it is important to keep lock until restoration the - * settings to prevent others from misuse of filp->f_op or - * filp->private_data. - */ - mutex_lock(&dev->struct_mutex); - - /* - * Set specific mmper's fops. And it will be restored by - * exynos_drm_gem_mmap_buffer to dev->driver->fops. - * This is used to call specific mapper temporarily. - */ - file_priv->filp->f_op = &exynos_drm_gem_fops; - - /* - * Set gem object to private_data so that specific mmaper - * can get the gem object. And it will be restored by - * exynos_drm_gem_mmap_buffer to drm_file. - */ - file_priv->filp->private_data = obj; + exynos_file_priv = file_priv->driver_priv; + anon_filp = exynos_file_priv->anon_filp; + anon_filp->private_data = obj;
- addr = vm_mmap(file_priv->filp, 0, args->size, - PROT_READ | PROT_WRITE, MAP_SHARED, 0); + addr = vm_mmap(anon_filp, 0, args->size, PROT_READ | PROT_WRITE, + MAP_SHARED, 0);
drm_gem_object_unreference(obj);
if (IS_ERR_VALUE(addr)) { - /* check filp->f_op, filp->private_data are restored */ - if (file_priv->filp->f_op == &exynos_drm_gem_fops) { - file_priv->filp->f_op = fops_get(dev->driver->fops); - file_priv->filp->private_data = file_priv; - } mutex_unlock(&dev->struct_mutex); return (int)addr; } diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.h b/drivers/gpu/drm/exynos/exynos_drm_gem.h index 702ec3a..fde860c 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_gem.h +++ b/drivers/gpu/drm/exynos/exynos_drm_gem.h @@ -122,6 +122,9 @@ int exynos_drm_gem_map_offset_ioctl(struct drm_device *dev, void *data, int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv);
+int exynos_drm_gem_mmap_buffer(struct file *filp, + struct vm_area_struct *vma); + /* map user space allocated by malloc to pages. */ int exynos_drm_gem_userptr_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv);