linux-kernel - [PATCH] drm/msm: Do not unpin/evict exported dma-buf's

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Date:   Mon, 26 Apr 2021 16:53:25 -0700
From:   Rob Clark <robdclark@...il.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     Rob Clark <robdclark@...omium.org>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        linux-arm-msm@...r.kernel.org (open list:DRM DRIVER FOR MSM ADRENO GPU),
        freedreno@...ts.freedesktop.org (open list:DRM DRIVER FOR MSM ADRENO
        GPU), linux-kernel@...r.kernel.org (open list),
        linux-media@...r.kernel.org (open list:DMA BUFFER SHARING FRAMEWORK),
        linaro-mm-sig@...ts.linaro.org (moderated list:DMA BUFFER SHARING
        FRAMEWORK)
Subject: [PATCH] drm/msm: Do not unpin/evict exported dma-buf's

From: Rob Clark <robdclark@...omium.org>

Our initial logic for excluding dma-bufs was not quite right.  In
particular we want msm_gem_get/put_pages() path used for exported
dma-bufs to increment/decrement the pin-count.

Also, in case the importer is vmap'ing the dma-buf, we need to be
sure to update the object's status, because it is now no longer
potentially evictable.

Fixes: 63f17ef83428 drm/msm: Support evicting GEM objects to swap
Signed-off-by: Rob Clark <robdclark@...omium.org>
---
 drivers/gpu/drm/msm/msm_gem.c | 16 +++++++++++++++-
 drivers/gpu/drm/msm/msm_gem.h |  4 ++--
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 09ef4ec6eb34..17f85d2f23ab 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -190,13 +190,25 @@ struct page **msm_gem_get_pages(struct drm_gem_object *obj)
 	}
 
 	p = get_pages(obj);
+
+	if (!IS_ERR(p)) {
+		msm_obj->pin_count++;
+		update_inactive(msm_obj);
+	}
+
 	msm_gem_unlock(obj);
 	return p;
 }
 
 void msm_gem_put_pages(struct drm_gem_object *obj)
 {
-	/* when we start tracking the pin count, then do something here */
+	struct msm_gem_object *msm_obj = to_msm_bo(obj);
+
+	msm_gem_lock(obj);
+	msm_obj->pin_count--;
+	GEM_WARN_ON(msm_obj->pin_count < 0);
+	update_inactive(msm_obj);
+	msm_gem_unlock(obj);
 }
 
 int msm_gem_mmap_obj(struct drm_gem_object *obj,
@@ -646,6 +658,8 @@ static void *get_vaddr(struct drm_gem_object *obj, unsigned madv)
 			ret = -ENOMEM;
 			goto fail;
 		}
+
+		update_inactive(msm_obj);
 	}
 
 	return msm_obj->vaddr;
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index 1b519fcd8418..66fb40b87122 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -228,7 +228,7 @@ static inline bool is_active(struct msm_gem_object *msm_obj)
 /* imported/exported objects are not purgeable: */
 static inline bool is_unpurgeable(struct msm_gem_object *msm_obj)
 {
-	return msm_obj->base.dma_buf && msm_obj->base.import_attach;
+	return msm_obj->base.import_attach || msm_obj->pin_count;
 }
 
 static inline bool is_purgeable(struct msm_gem_object *msm_obj)
@@ -278,7 +278,7 @@ static inline void mark_unpurgeable(struct msm_gem_object *msm_obj)
 
 static inline bool is_unevictable(struct msm_gem_object *msm_obj)
 {
-	return is_unpurgeable(msm_obj) || msm_obj->pin_count || msm_obj->vaddr;
+	return is_unpurgeable(msm_obj) || msm_obj->vaddr;
 }
 
 static inline void mark_evictable(struct msm_gem_object *msm_obj)
-- 
2.30.2