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From: Boris Brezillon <boris.brezillon@collabora.com>
To: "Boris Brezillon" <boris.brezillon@collabora.com>,
	"Steven Price" <steven.price@arm.com>,
	"Liviu Dudau" <liviu.dudau@arm.com>,
	"Adrián Larumbe" <adrian.larumbe@collabora.com>
Cc: dri-devel@lists.freedesktop.org, kernel@collabora.com,
	Eric Smith <eric.smith@collabora.com>
Subject: [PATCH v4 4/5] drm/panthor: Fix an off-by-one in the heap context retrieval logic
Date: Thu,  2 May 2024 18:51:57 +0200	[thread overview]
Message-ID: <20240502165158.1458959-5-boris.brezillon@collabora.com> (raw)
In-Reply-To: <20240502165158.1458959-1-boris.brezillon@collabora.com>

The heap ID is used to index the heap context pool, and allocating
in the [1:MAX_HEAPS_PER_POOL] leads to an off-by-one. This was
originally to avoid returning a zero heap handle, but given the handle
is formed with (vm_id << 16) | heap_id, with vm_id > 0, we already can't
end up with a valid heap handle that's zero.

v4:
- s/XA_FLAGS_ALLOC1/XA_FLAGS_ALLOC/

v3:
- Allocate in the [0:MAX_HEAPS_PER_POOL-1] range

v2:
- New patch

Fixes: 9cca48fa4f89 ("drm/panthor: Add the heap logical block")
Reported-by: Eric Smith <eric.smith@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Eric Smith <eric.smith@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_heap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_heap.c b/drivers/gpu/drm/panthor/panthor_heap.c
index b0fc5b9ee847..95a1c6c9f35e 100644
--- a/drivers/gpu/drm/panthor/panthor_heap.c
+++ b/drivers/gpu/drm/panthor/panthor_heap.c
@@ -323,7 +323,8 @@ int panthor_heap_create(struct panthor_heap_pool *pool,
 	if (!pool->vm) {
 		ret = -EINVAL;
 	} else {
-		ret = xa_alloc(&pool->xa, &id, heap, XA_LIMIT(1, MAX_HEAPS_PER_POOL), GFP_KERNEL);
+		ret = xa_alloc(&pool->xa, &id, heap,
+			       XA_LIMIT(0, MAX_HEAPS_PER_POOL - 1), GFP_KERNEL);
 		if (!ret) {
 			void *gpu_ctx = panthor_get_heap_ctx(pool, id);
 
@@ -543,7 +544,7 @@ panthor_heap_pool_create(struct panthor_device *ptdev, struct panthor_vm *vm)
 	pool->vm = vm;
 	pool->ptdev = ptdev;
 	init_rwsem(&pool->lock);
-	xa_init_flags(&pool->xa, XA_FLAGS_ALLOC1);
+	xa_init_flags(&pool->xa, XA_FLAGS_ALLOC);
 	kref_init(&pool->refcount);
 
 	pool->gpu_contexts = panthor_kernel_bo_create(ptdev, vm, bosize,
-- 
2.44.0


  parent reply	other threads:[~2024-05-02 16:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-02 16:51 [PATCH v4 0/5] drm/panthor: Collection of tiler heap related fixes Boris Brezillon
2024-05-02 16:51 ` [PATCH v4 1/5] drm/panthor: Fix tiler OOM handling to allow incremental rendering Boris Brezillon
2024-05-02 16:51 ` [PATCH v4 2/5] drm/panthor: Make sure the tiler initial/max chunks are consistent Boris Brezillon
2024-05-02 16:51 ` [PATCH v4 3/5] drm/panthor: Relax the constraints on the tiler chunk size Boris Brezillon
2024-05-02 16:51 ` Boris Brezillon [this message]
2024-05-03  8:26   ` [PATCH v4 4/5] drm/panthor: Fix an off-by-one in the heap context retrieval logic Steven Price
2024-05-03 10:22   ` Liviu Dudau
2024-05-02 16:51 ` [PATCH v4 5/5] drm/panthor: Document drm_panthor_tiler_heap_destroy::handle validity constraints Boris Brezillon
2024-05-03 10:22   ` Liviu Dudau
2024-05-13 11:41 ` [PATCH v4 0/5] drm/panthor: Collection of tiler heap related fixes Boris Brezillon

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