[PATCH 0/2] annotate i915_gem_object_trylock() as __must_check

[PATCH 0/2] annotate i915_gem_object_trylock() as __must_check

[Rolf Eike Beer]

[-- Attachment #1: Type: text/plain, Size: 809 bytes --]

A while ago I did an attempt to convert some *_trylock*() functions to 
__must_check annotation. I have refreshed that and the only new compile error 
I found was in i915/gt/selftest_migrate.c.

Here is what I have come up with as a solution for this. I have not observed 
any actual error about this, so you may prefer an entirely different way.

Regards,

Eike
-- 
Rolf Eike Beer

emlix GmbH
Headquarters: Berliner Str. 12, 37073 Göttingen, Germany
Phone +49 (0)551 30664-0, e-mail info@emlix.com
District Court of Göttingen, Registry Number HR B 3160
Managing Directors: Heike Jordan, Dr. Uwe Kracke
VAT ID No. DE 205 198 055
Office Berlin: Panoramastr. 1, 10178 Berlin, Germany
Office Bonn: Bachstr. 6, 53115 Bonn, Germany
http://www.emlix.com

emlix - your embedded Linux partner

[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 313 bytes --]

[PATCH 1/2] drm/i915/selftests: check the return value of i915_gem_object_trylock()

[Rolf Eike Beer]

A trylock can fail, in which case operating on the object is unsafe and
unconditionally unlocking is wrong.

Signed-off-by: Rolf Eike Beer <eb@emlix.com>
---
 drivers/gpu/drm/i915/gt/selftest_migrate.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/selftest_migrate.c b/drivers/gpu/drm/i915/gt/selftest_migrate.c
index ca460cee4f8b..b2cb501febe8 100644
--- a/drivers/gpu/drm/i915/gt/selftest_migrate.c
+++ b/drivers/gpu/drm/i915/gt/selftest_migrate.c
@@ -822,7 +822,10 @@ create_init_lmem_internal(struct intel_gt *gt, size_t sz, bool try_lmem)
 			return obj;
 	}
 
-	i915_gem_object_trylock(obj, NULL);
+	if (!i915_gem_object_trylock(obj, NULL)) {
+		i915_gem_object_put(obj);
+		return ERR_PTR(-EBUSY);
+	}
 	err = i915_gem_object_pin_pages(obj);
 	if (err) {
 		i915_gem_object_unlock(obj);
-- 
2.47.1


-- 
Rolf Eike Beer

emlix GmbH
Headquarters: Berliner Str. 12, 37073 Göttingen, Germany
Phone +49 (0)551 30664-0, e-mail info@emlix.com
District Court of Göttingen, Registry Number HR B 3160
Managing Directors: Heike Jordan, Dr. Uwe Kracke
VAT ID No. DE 205 198 055
Office Berlin: Panoramastr. 1, 10178 Berlin, Germany
Office Bonn: Bachstr. 6, 53115 Bonn, Germany
http://www.emlix.com

emlix - your embedded Linux partner

[PATCH 2/2] drm/i915: mark i915_gem_object_trylock() as __must_check

[Rolf Eike Beer]

When you don't look at the return code you can't know if you actually got the
lock.

Signed-off-by: Rolf Eike Beer <eb@emlix.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 3dc61cbd2e11..b6da8b561ae0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -198,8 +198,8 @@ static inline int i915_gem_object_lock_interruptible(struct drm_i915_gem_object
 	return __i915_gem_object_lock(obj, ww, true);
 }
 
-static inline bool i915_gem_object_trylock(struct drm_i915_gem_object *obj,
-					   struct i915_gem_ww_ctx *ww)
+static inline bool __must_check i915_gem_object_trylock(struct drm_i915_gem_object *obj,
+							struct i915_gem_ww_ctx *ww)
 {
 	if (!ww)
 		return dma_resv_trylock(obj->base.resv);
-- 
2.47.1


-- 
Rolf Eike Beer

emlix GmbH
Headquarters: Berliner Str. 12, 37073 Göttingen, Germany
Phone +49 (0)551 30664-0, e-mail info@emlix.com
District Court of Göttingen, Registry Number HR B 3160
Managing Directors: Heike Jordan, Dr. Uwe Kracke
VAT ID No. DE 205 198 055
Office Berlin: Panoramastr. 1, 10178 Berlin, Germany
Office Bonn: Bachstr. 6, 53115 Bonn, Germany
http://www.emlix.com

emlix - your embedded Linux partner