linux-kernel - [PATCH] drm/panthor: Lock XArray when getting entries for heap and VM

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Message-ID: <20241106120748.290697-1-liviu.dudau@arm.com>
Date: Wed,  6 Nov 2024 12:07:48 +0000
From: Liviu Dudau <liviu.dudau@....com>
To: Boris Brezillon <boris.brezillon@...labora.com>
Cc: Steven Price <steven.price@....com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Jann Horn <jannh@...gle.com>
Subject: [PATCH] drm/panthor: Lock XArray when getting entries for heap and VM

Similar to cac075706f29 ("drm/panthor: Fix race when converting
group handle to group object") we need to use the XArray's internal
locking when retrieving a pointer from there for heap and vm.

Reported-by: Jann Horn <jannh@...gle.com>
Cc: Boris Brezillon <boris.brezillon@...labora.com>
Cc: Steven Price <steven.price@....com>
Signed-off-by: Liviu Dudau <liviu.dudau@....com>
---
 drivers/gpu/drm/panthor/panthor_heap.c | 15 +++++++++++++--
 drivers/gpu/drm/panthor/panthor_mmu.c  |  2 ++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
index 3796a9eb22af2..fe0bcb6837f74 100644
--- a/drivers/gpu/drm/panthor/panthor_heap.c
+++ b/drivers/gpu/drm/panthor/panthor_heap.c
@@ -351,6 +351,17 @@ int panthor_heap_create(struct panthor_heap_pool *pool,
 	return ret;
 }
 
+static struct panthor_heap *panthor_heap_from_id(struct pathor_heap_pool *pool, u32 id)
+{
+	struct panthor_heap *heap;
+
+	xa_lock(&pool->xa);
+	heap = xa_load(&pool->xa, id);
+	xa_unlock(&pool->va);
+
+	return heap;
+}
+
 /**
  * panthor_heap_return_chunk() - Return an unused heap chunk
  * @pool: The pool this heap belongs to.
@@ -375,7 +386,7 @@ int panthor_heap_return_chunk(struct panthor_heap_pool *pool,
 		return -EINVAL;
 
 	down_read(&pool->lock);
-	heap = xa_load(&pool->xa, heap_id);
+	heap = panthor_heap_from_id(pool, heap_id);
 	if (!heap) {
 		ret = -EINVAL;
 		goto out_unlock;
@@ -438,7 +449,7 @@ int panthor_heap_grow(struct panthor_heap_pool *pool,
 		return -EINVAL;
 
 	down_read(&pool->lock);
-	heap = xa_load(&pool->xa, heap_id);
+	heap = panthor_heap_from_id(pool, heap_id);
 	if (!heap) {
 		ret = -EINVAL;
 		goto out_unlock;
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 8ca85526491e6..8b5cda9d21768 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1580,7 +1580,9 @@ panthor_vm_pool_get_vm(struct panthor_vm_pool *pool, u32 handle)
 {
 	struct panthor_vm *vm;
 
+	xa_lock(&pool->xa);
 	vm = panthor_vm_get(xa_load(&pool->xa, handle));
+	xa_unlock(&pool->va);
 
 	return vm;
 }
-- 
2.47.0