Currently when allocating a framebuffer fails, the gem object gets
unrefed at the bottom of the call stack in __intel_framebuffer_create,
not where it gets refed, which is in intel_framebuffer_create_for_mode
(via i915_gem_alloc_object) and in intel_user_framebuffer_create
(via drm_gem_object_lookup).
This invites mistakes: __intel_framebuffer_create is also called from
intelfb_alloc, and as discovered by Tvrtko Ursulin, a double unref
was introduced there with a8bb6818270c ("drm/i915: Fix error path leak
in fbdev fb allocation").
As suggested by Ville Syrjälä, fix the double unref and improve code
clarity by moving the unref away from __intel_framebuffer_create to
where the gem object gets refed.
Based on Tvrtko Ursulin's original v2.
v3: On fb alloc failure, unref gem object where it gets refed,
fix double unref in separate commit (Ville Syrjälä)
v4: Lock struct_mutex on unref (Chris Wilson)
v5: Rebase on drm-intel-nightly 2015y-09m-01d-09h-06m-08s UTC,
rephrase commit message (Jani Nicula)
Tested-by: Pierre Moreau <pierre.mor...@free.fr>
[MBP 5,3 2009 nvidia MCP79 + G96 pre-retina]
Tested-by: Paul Hordiienko <pvt.g...@gmail.com>
[MBP 6,2 2010 intel ILK + nvidia GT216 pre-retina]
Tested-by: William Brown <will...@blackhats.net.au>
[MBP 8,2 2011 intel SNB + amd turks pre-retina]
Tested-by: Lukas Wunner <lu...@wunner.de>
[MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina]
Tested-by: Bruno Bierbaumer <br...@bierbaumer.net>
[MBP 11,3 2013 intel HSW + nvidia GK107 retina]
Fixes: a8bb6818270c ("drm/i915: Fix error path leak in fbdev fb
allocation")
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Signed-off-by: Lukas Wunner <lu...@wunner.de>
Reviewed-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 0811238..7fc6d9e 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10078,20 +10078,17 @@ __intel_framebuffer_create(struct drm_device *dev,
int ret;
intel_fb = kzalloc(sizeof(*intel_fb), GFP_KERNEL);
- if (!intel_fb) {
- drm_gem_object_unreference(&obj->base);
+ if (!intel_fb)
return ERR_PTR(-ENOMEM);
- }
ret = intel_framebuffer_init(dev, intel_fb, mode_cmd, obj);
if (ret)
goto err;
return &intel_fb->base;
+
err:
- drm_gem_object_unreference(&obj->base);
kfree(intel_fb);
-
return ERR_PTR(ret);
}
@@ -10131,6 +10128,7 @@ intel_framebuffer_create_for_mode(struct drm_device
*dev,
struct drm_display_mode *mode,
int depth, int bpp)
{
+ struct drm_framebuffer *fb;
struct drm_i915_gem_object *obj;
struct drm_mode_fb_cmd2 mode_cmd = { 0 };
@@ -10145,7 +10143,11 @@ intel_framebuffer_create_for_mode(struct drm_device
*dev,
bpp);
mode_cmd.pixel_format = drm_mode_legacy_fb_format(bpp, depth);
- return intel_framebuffer_create(dev, &mode_cmd, obj);
+ fb = intel_framebuffer_create(dev, &mode_cmd, obj);
+ if (IS_ERR(fb))
+ drm_gem_object_unreference_unlocked(&obj->base);
+
+ return fb;
}
static struct drm_framebuffer *
@@ -14548,6 +14550,7 @@ intel_user_framebuffer_create(struct drm_device *dev,
struct drm_file *filp,
struct drm_mode_fb_cmd2 *mode_cmd)
{
+ struct drm_framebuffer *fb;
struct drm_i915_gem_object *obj;
obj = to_intel_bo(drm_gem_object_lookup(dev, filp,
@@ -14555,7 +14558,11 @@ intel_user_framebuffer_create(struct drm_device *dev,
if (&obj->base == NULL)
return ERR_PTR(-ENOENT);
- return intel_framebuffer_create(dev, mode_cmd, obj);
+ fb = intel_framebuffer_create(dev, mode_cmd, obj);
+ if (IS_ERR(fb))
+ drm_gem_object_unreference_unlocked(&obj->base);
+
+ return fb;
}
#ifndef CONFIG_DRM_FBDEV_EMULATION
--
1.8.5.2 (Apple Git-48)
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
