From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
We had two failure modes here:
1.
Deadlock in intelfb_alloc failure path where it calls
drm_framebuffer_remove, which grabs the struct mutex and intelfb_create
(caller of intelfb_alloc) was already holding it.
2.
Deadlock in intelfb_create failure path where it calls
drm_framebuffer_unreference, which grabs the struct mutex and
intelfb_create was already holding it.
v2:
* Reformat commit msg to 72 chars. (Lukas Wunner)
* Add third failure mode. (Lukas Wunner)
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)
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Paul Hordiienko <pvt.gord@xxxxxxxxx>
[MBP 6,2 2010 intel ILK + nvidia GT216 pre-retina]
Tested-by: William Brown <william@xxxxxxxxxxxxxxxx>
[MBP 8,2 2011 intel SNB + amd turks pre-retina]
Tested-by: Lukas Wunner <lukas@xxxxxxxxx>
[MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina]
Tested-by: Bruno Bierbaumer <bruno@xxxxxxxxxxxxxx>
[MBP 11,3 2013 intel HSW + nvidia GK107 retina -- work in progress]
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Fixes: 60a5ca015ffd ("drm/i915: Add locking around
framebuffer_references--")
Reported-by: Lukas Wunner <lukas@xxxxxxxxx>
[Lukas: Create v3 + v4 based on Tvrtko's v2]
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_fbdev.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index 7eff33f..dd138aa 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -140,7 +140,7 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
{
struct intel_fbdev *ifbdev =
container_of(helper, struct intel_fbdev, helper);
- struct drm_framebuffer *fb;
+ struct drm_framebuffer *fb = NULL;
struct drm_device *dev = helper->dev;
struct drm_mode_fb_cmd2 mode_cmd = {};
struct drm_i915_gem_object *obj;
@@ -158,6 +158,8 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp,
sizes->surface_depth);
+ mutex_lock(&dev->struct_mutex);
+
size = mode_cmd.pitches[0] * mode_cmd.height;
size = PAGE_ALIGN(size);
obj = i915_gem_object_create_stolen(dev, size);
@@ -179,18 +181,21 @@ static int intelfb_alloc(struct drm_fb_helper *helper,
ret = intel_pin_and_fence_fb_obj(NULL, fb, NULL, NULL, NULL);
if (ret) {
DRM_ERROR("failed to pin obj: %d\n", ret);
- goto out_fb;
+ goto out_unref;
}
+ mutex_unlock(&dev->struct_mutex);
+
ifbdev->fb = to_intel_framebuffer(fb);
return 0;
-out_fb:
- drm_framebuffer_remove(fb);
out_unref:
drm_gem_object_unreference(&obj->base);
out:
+ mutex_unlock(&dev->struct_mutex);
+ if (fb)
+ drm_framebuffer_remove(fb);
return ret;
}
@@ -208,8 +213,6 @@ static int intelfb_create(struct drm_fb_helper *helper,
int size, ret;
bool prealloc = false;
- mutex_lock(&dev->struct_mutex);
-
if (intel_fb &&
(sizes->fb_width > intel_fb->base.width ||
sizes->fb_height > intel_fb->base.height)) {
@@ -224,7 +227,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
DRM_DEBUG_KMS("no BIOS fb, allocating a new one\n");
ret = intelfb_alloc(helper, sizes);
if (ret)
- goto out_unlock;
+ return ret;
intel_fb = ifbdev->fb;
} else {
DRM_DEBUG_KMS("re-using BIOS fb\n");
@@ -236,6 +239,8 @@ static int intelfb_create(struct drm_fb_helper *helper,
obj = intel_fb->obj;
size = obj->base.size;
+ mutex_lock(&dev->struct_mutex);
+
info = framebuffer_alloc(0, &dev->pdev->dev);
if (!info) {
ret = -ENOMEM;
@@ -306,7 +311,6 @@ static int intelfb_create(struct drm_fb_helper *helper,
out_unpin:
i915_gem_object_ggtt_unpin(obj);
drm_gem_object_unreference(&obj->base);
-out_unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
}
--
1.8.5.2 (Apple Git-48)
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