[Intel-gfx] [PATCH 2/2] drm/i915: Handle vm_mmap error during I915_GEM_MMAP ioctl with WC set

[Joonas Lahtinen]

Add err goto label and use it when VMA can't be established or changes
underneath.

Fixes: 1816f9236303 ("drm/i915: Support creation of unbound wc user mappings for objects")
Reported-by: Adam Zabrocki <adamza at microsoft.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: <stable at vger.kernel.org> # v4.0+
Cc: Akash Goel <akash.goel at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Adam Zabrocki <adamza at microsoft.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f1d594a53978..97cbc0e27e3e 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1738,6 +1738,9 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	addr = vm_mmap(obj->base.filp, 0, args->size,
 		       PROT_READ | PROT_WRITE, MAP_SHARED,
 		       args->offset);
+	if (IS_ERR((void *)addr))
+		goto err;
+
 	if (args->flags & I915_MMAP_WC) {
 		struct mm_struct *mm = current->mm;
 		struct vm_area_struct *vma;
@@ -1753,17 +1756,22 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 		else
 			addr = -ENOMEM;
 		up_write(&mm->mmap_sem);
+		if (IS_ERR((void *)addr))
+			goto err;
 
 		/* This may race, but that's ok, it only gets set */
 		WRITE_ONCE(obj->frontbuffer_ggtt_origin, ORIGIN_CPU);
 	}
 	i915_gem_object_put(obj);
-	if (IS_ERR((void *)addr))
-		return addr;
 
 	args->addr_ptr = (uint64_t) addr;
 
 	return 0;
+
+err:
+	i915_gem_object_put(obj);
+
+	return addr;
 }
 
 static unsigned int tile_row_pages(const struct drm_i915_gem_object *obj)
-- 
2.17.2