[broadcom-stblinux:drivers/next 8/22] drivers/platform/raspberrypi/vc-sm-cma/vc_sm.c:473 vc_sm_cma_import_dmabuf_internal() warn: unsigned 'import.kernel_id' is never less than zero.

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/Broadcom/stblinux drivers/next
head:   0cab822bca7a59667774725b83e948b71462290f
commit: 0d6409fd70afa8e0e43dfd8b15a419d84a2a802d [8/22] platform/raspberrypi: Add VideoCore shared memory support
config: powerpc-randconfig-2200-20261114 (https://download.01.org/0day-ci/archive/20261114/202611141042.Rxt6cuNo-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project c0693becb96c1610aeb87445a50df00d58a823cd)
smatch: v0.5.0-9187-g5189e3fb

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202611141042.Rxt6cuNo-lkp@intel.com/

smatch warnings:
drivers/platform/raspberrypi/vc-sm-cma/vc_sm.c:473 vc_sm_cma_import_dmabuf_internal() warn: unsigned 'import.kernel_id' is never less than zero.

vim +473 drivers/platform/raspberrypi/vc-sm-cma/vc_sm.c

   404	
   405	/* Import a dma_buf to be shared with VC. */
   406	static int
   407	vc_sm_cma_import_dmabuf_internal(struct dma_buf *dma_buf,
   408					 int fd,
   409					 struct dma_buf **imported_buf)
   410	{
   411		DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
   412		struct dma_buf_attachment *attach = NULL;
   413		struct vc_sm_import_result result = { };
   414		struct vc_sm_buffer *buffer = NULL;
   415		struct vc_sm_import import = { };
   416		struct sg_table *sgt = NULL;
   417		dma_addr_t dma_addr;
   418		u32 cache_alias;
   419		int ret = 0;
   420		int status;
   421	
   422		/* Setup our allocation parameters */
   423		if (fd < 0)
   424			get_dma_buf(dma_buf);
   425		else
   426			dma_buf = dma_buf_get(fd);
   427	
   428		if (!dma_buf)
   429			return -EINVAL;
   430	
   431		attach = dma_buf_attach(dma_buf, &sm_state->device->dev);
   432		if (IS_ERR(attach)) {
   433			ret = PTR_ERR(attach);
   434			goto error;
   435		}
   436	
   437		sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
   438		if (IS_ERR(sgt)) {
   439			ret = PTR_ERR(sgt);
   440			goto error;
   441		}
   442	
   443		/* Verify that the address block is contiguous */
   444		if (sgt->nents != 1) {
   445			ret = -ENOMEM;
   446			goto error;
   447		}
   448	
   449		/* Allocate local buffer to track this allocation. */
   450		buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
   451		if (!buffer) {
   452			ret = -ENOMEM;
   453			goto error;
   454		}
   455	
   456		import.type = VC_SM_ALLOC_NON_CACHED;
   457		dma_addr = sg_dma_address(sgt->sgl);
   458		import.addr = (u32)dma_addr;
   459		cache_alias = import.addr & VC_SM_VC4_ALIAS_MASK;
   460		if (cache_alias != VC_SM_VC4_UNCACHED_ALIAS &&
   461		    cache_alias != VC_SM_VC4_COHERENT_ALIAS) {
   462			dev_err(&sm_state->device->dev, "%s: Expecting an uncached alias for dma_addr %pad\n",
   463				__func__, &dma_addr);
   464			/*
   465			 * Note that this assumes we're on >= Pi2, but it implies a
   466			 * DT configuration error.
   467			 */
   468			import.addr |= VC_SM_VC4_UNCACHED_ALIAS;
   469		}
   470		import.size = sg_dma_len(sgt->sgl);
   471		import.allocator = current->tgid;
   472		import.kernel_id = get_kernel_id(buffer);
 > 473		if (import.kernel_id < 0) {
   474			ret = import.kernel_id;
   475			goto error;
   476		}
   477	
   478		memcpy(import.name, VC_SM_RESOURCE_NAME_DEFAULT,
   479		       sizeof(VC_SM_RESOURCE_NAME_DEFAULT));
   480	
   481		/* Allocate the videocore buffer. */
   482		status = vc_sm_cma_vchi_import(sm_state->sm_handle, &import, &result,
   483					       &sm_state->int_trans_id);
   484		if (status == -EINTR) {
   485			dev_dbg(&sm_state->device->dev,
   486				"%s: requesting import memory action restart (trans_id: %u)\n",
   487				__func__, sm_state->int_trans_id);
   488			ret = -ERESTARTSYS;
   489			sm_state->restart_sys = -EINTR;
   490			sm_state->int_action = VC_SM_MSG_TYPE_IMPORT;
   491			goto error;
   492		} else if (status || !result.res_handle) {
   493			dev_dbg(&sm_state->device->dev,
   494				"%s: failed to import memory on videocore (status: %u, trans_id: %u)\n",
   495				 __func__, status, sm_state->int_trans_id);
   496			ret = -ENOMEM;
   497			goto error;
   498		}
   499	
   500		mutex_init(&buffer->lock);
   501		INIT_LIST_HEAD(&buffer->attachments);
   502		memcpy(buffer->name, import.name,
   503		       min(sizeof(buffer->name), sizeof(import.name) - 1));
   504	
   505		/* Keep track of the buffer we created. */
   506		buffer->vc_handle = result.res_handle;
   507		buffer->size = import.size;
   508		buffer->vpu_state = VPU_MAPPED;
   509	
   510		buffer->imported_dma_buf = dma_buf;
   511	
   512		buffer->attach = attach;
   513		buffer->sgt = sgt;
   514		buffer->dma_addr = dma_addr;
   515		buffer->in_use = true;
   516		buffer->kernel_id = import.kernel_id;
   517	
   518		/*
   519		 * We're done - we need to export a new dmabuf chaining through most
   520		 * functions, but enabling us to release our own internal references
   521		 * here.
   522		 */
   523		exp_info.ops = &dma_buf_import_ops;
   524		exp_info.size = import.size;
   525		exp_info.flags = O_RDWR;
   526		exp_info.priv = buffer;
   527	
   528		buffer->dma_buf = dma_buf_export(&exp_info);
   529		if (IS_ERR(buffer->dma_buf)) {
   530			ret = PTR_ERR(buffer->dma_buf);
   531			goto error;
   532		}
   533	
   534		vc_sm_add_resource(buffer);
   535	
   536		*imported_buf = buffer->dma_buf;
   537	
   538		return 0;
   539	
   540	error:
   541		if (result.res_handle) {
   542			struct vc_sm_free_t free = { result.res_handle, 0 };
   543	
   544			vc_sm_cma_vchi_free(sm_state->sm_handle, &free,
   545					    &sm_state->int_trans_id);
   546		}
   547		free_kernel_id(import.kernel_id);
   548		kfree(buffer);
   549		if (sgt)
   550			dma_buf_unmap_attachment_unlocked(attach, sgt,
   551							  DMA_BIDIRECTIONAL);
   552		if (attach)
   553			dma_buf_detach(dma_buf, attach);
   554		dma_buf_put(dma_buf);
   555		return ret;
   556	}
   557	

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