TEE and OP-TEE fixes for v5.16

- Fixes a race when a tee_shm reaches reference count 0 and is about to
   be teared down
 - Fixes an incorrect page free bug in an error path of the OP-TEE shared
   memory pool handling
 - Suppresses a false positive kmemleak report when allocating driver
   private shared memory buffers for OP-TEE
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Merge tag 'fixes-for-v5.16' of https://git.linaro.org/people/jens.wiklander/linux-tee into arm/fixes

TEE and OP-TEE fixes for v5.16

- Fixes a race when a tee_shm reaches reference count 0 and is about to
  be teared down
- Fixes an incorrect page free bug in an error path of the OP-TEE shared
  memory pool handling
- Suppresses a false positive kmemleak report when allocating driver
  private shared memory buffers for OP-TEE

* tag 'fixes-for-v5.16' of https://git.linaro.org/people/jens.wiklander/linux-tee:
  optee: Suppress false positive kmemleak report in optee_handle_rpc()
  tee: optee: Fix incorrect page free bug
  tee: handle lookup of shm with reference count 0

Link: https://lore.kernel.org/r/20211216150745.GA3347954@jade
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

include/linux/tee_drv.h

@@ -195,7 +195,7 @@ int tee_session_calc_client_uuid(uuid_t *uuid, u32 connection_method,
  * @offset:	offset of buffer in user space
  * @pages:	locked pages from userspace
  * @num_pages:	number of locked pages
- * @dmabuf:	dmabuf used to for exporting to user space
+ * @refcount:	reference counter
  * @flags:	defined by TEE_SHM_* in tee_drv.h
  * @id:		unique id of a shared memory object on this device, shared
  *		with user space
@@ -214,7 +214,7 @@ struct tee_shm {
 	unsigned int offset;
 	struct page **pages;
 	size_t num_pages;
-	struct dma_buf *dmabuf;
+	refcount_t refcount;
 	u32 flags;
 	int id;
 	u64 sec_world_id;