[bug report] mtd: nand: omap2: fix return value check in omap_nand_probe()

[Dan Carpenter]

Hello Wei Yongjun,

The patch de3bfc4a1616: "mtd: nand: omap2: fix return value check in
omap_nand_probe()" from Jul 14, 2016, leads to the following static
checker warning:

	drivers/mtd/nand/omap2.c:2173 omap_nand_probe()
	error: 'info->dma' dereferencing possible ERR_PTR()

drivers/mtd/nand/omap2.c
  1921          case NAND_OMAP_PREFETCH_DMA:
  1922                  dma_cap_zero(mask);
  1923                  dma_cap_set(DMA_SLAVE, mask);
  1924                  info->dma = dma_request_chan(pdev->dev.parent, "rxtx");
  1925  
  1926                  if (IS_ERR(info->dma)) {
                                   ^^^^^^^^^
  1927                          dev_err(&pdev->dev, "DMA engine request failed\n");
  1928                          err = PTR_ERR(info->dma);
  1929                          goto return_error;
  1930                  } else {
  1931                          struct dma_slave_config cfg;
  1932  
  1933                          memset(&cfg, 0, sizeof(cfg));
  1934                          cfg.src_addr = info->phys_base;
  1935                          cfg.dst_addr = info->phys_base;
  1936                          cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
  1937                          cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
  1938                          cfg.src_maxburst = 16;
  1939                          cfg.dst_maxburst = 16;
  1940                          err = dmaengine_slave_config(info->dma, &cfg);
  1941                          if (err) {
  1942                                  dev_err(&pdev->dev, "DMA engine slave config failed: %d\n",
  1943                                          err);
  1944                                  goto return_error;
  1945                          }
  1946                          nand_chip->read_buf   = omap_read_buf_dma_pref;
  1947                          nand_chip->write_buf  = omap_write_buf_dma_pref;
  1948                  }
  1949                  break;
  1950  

[ snip ]

  2170  
  2171  return_error:
  2172          if (info->dma)
  2173                  dma_release_channel(info->dma);
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
We can't pass error pointers to dma_release_channel().  I can't compile
this code though, so I'm not going to patch it.

  2174          if (nand_chip->ecc.priv) {
  2175                  nand_bch_free(nand_chip->ecc.priv);
  2176                  nand_chip->ecc.priv = NULL;
  2177          }
  2178          return err;
  2179  }

regards,
dan carpenter