Re: mmc: omap: Fix DMA configuration to not rely on device id

[Tony Lindgren <tony@atomide.com>]

* Dan Carpenter <dan.carpenter@oracle.com> [131202 00:07]:
> Hello Tony Lindgren,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 31ee9181eb92: "mmc: omap: Fix DMA configuration to not rely 
> on device id" from Nov 26, 2013, leads to the following Smatch 
> complaint:
> 
> drivers/mmc/host/omap.c:1468 mmc_omap_probe()
> 	 error: we previously assumed 'res' could be null (see line 1410)
> 
> drivers/mmc/host/omap.c
>   1409		res = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
>   1410		if (res)
>                     ^^^
> Patch introduces a check.
> 
>   1411			sig = res->start;
>   1412		host->dma_rx = dma_request_slave_channel_compat(mask,
>   1413					omap_dma_filter_fn, &sig, &pdev->dev, "rx");
>   1414		if (!host->dma_rx)
>   1415			dev_warn(host->dev, "unable to obtain RX DMA engine channel %u\n",
>   1416				sig);
>   1417	
>   1418		ret = request_irq(host->irq, mmc_omap_irq, 0, DRIVER_NAME, host);
>   1419		if (ret)
>   1420			goto err_free_dma;
>   1421	
>   1422		if (pdata->init != NULL) {
>   1423			ret = pdata->init(&pdev->dev);
>   1424			if (ret < 0)
>   1425				goto err_free_irq;
>   1426		}
>   1427	
>   1428		host->nr_slots = pdata->nr_slots;
>   1429		host->reg_shift = (mmc_omap7xx() ? 1 : 2);
>   1430	
>   1431		host->mmc_omap_wq = alloc_workqueue("mmc_omap", 0, 0);
>   1432		if (!host->mmc_omap_wq)
>   1433			goto err_plat_cleanup;
>   1434	
>   1435		for (i = 0; i < pdata->nr_slots; i++) {
>   1436			ret = mmc_omap_new_slot(host, i);
>   1437			if (ret < 0) {
>   1438				while (--i >= 0)
>   1439					mmc_omap_remove_slot(host->slots[i]);
>   1440	
>   1441				goto err_destroy_wq;
>   1442			}
>   1443		}
>   1444	
>   1445		return 0;
>   1446	
>   1447	err_destroy_wq:
>   1448		destroy_workqueue(host->mmc_omap_wq);
>   1449	err_plat_cleanup:
>   1450		if (pdata->cleanup)
>   1451			pdata->cleanup(&pdev->dev);
>   1452	err_free_irq:
>   1453		free_irq(host->irq, host);
>   1454	err_free_dma:
>   1455		if (host->dma_tx)
>   1456			dma_release_channel(host->dma_tx);
>   1457		if (host->dma_rx)
>   1458			dma_release_channel(host->dma_rx);
>   1459		clk_put(host->fclk);
>   1460	err_free_iclk:
>   1461		clk_disable(host->iclk);
>   1462		clk_put(host->iclk);
>   1463	err_free_mmc_host:
>   1464		iounmap(host->virt_base);
>   1465	err_ioremap:
>   1466		kfree(host);
>   1467	err_free_mem_region:
>   1468		release_mem_region(res->start, resource_size(res));
>                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Existing unchecked dereferences.
> 
>   1469		return ret;
>   1470	}

Oops. Thanks a lot for reporting this, I'll post a fix for it separately.

Looks like the minimal fix is to add what at least omap_hsmmc.c is doing:

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res)
	release_mem_region(res->start, resource_size(res));

Regards,

Tony