[PATCH v6] tty: 8250: fix a missing check for pci_ioremap_bar

[Aditya Pakki]

pci_ioremap_bar could fail. The patch returns in case of failure to
acquire IOMEM. It also releases the acquired resource in the exit path.

Signed-off-by: Aditya Pakki <pakki001@xxxxxxx>

---
v5: change pci_iounmap to iounmap to pass kbuild errors in other arch
v4: Missed resource release in dma_probe failure.
v3: Change the order of pci_iounmap and dw_dma_remove
v2: Failed to release resource in exit path and incorrect code in non
DMA case, suggested by Andy Shevchenko
v1: Missed return by default in CONFIG_SERIAL_8250_DMA, suggested by
Jiri Slaby
---
 drivers/tty/serial/8250/8250_lpss.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
index 53ca9ba6ab4b..c7c7bf5d7e5e 100644
--- a/drivers/tty/serial/8250/8250_lpss.c
+++ b/drivers/tty/serial/8250/8250_lpss.c
@@ -170,14 +170,18 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
 	int ret;
 
 	chip->dev = &pdev->dev;
+	chip->pdata = &qrk_serial_dma_pdata;
 	chip->irq = pci_irq_vector(pdev, 0);
 	chip->regs = pci_ioremap_bar(pdev, 1);
-	chip->pdata = &qrk_serial_dma_pdata;
+	if (!chip->regs)
+		return;
 
 	/* Falling back to PIO mode if DMA probing fails */
 	ret = dw_dma_probe(chip);
-	if (ret)
+	if (ret) {
+		iounmap(chip->regs);
 		return;
+	}
 
 	pci_try_set_mwi(pdev);
 
@@ -199,7 +203,10 @@ static void qrk_serial_exit_dma(struct lpss8250 *lpss)
 
 	if (!param->dma_dev)
 		return;
+
 	dw_dma_remove(&lpss->dma_chip);
+
+	iounmap(&lpss->dma_chip->regs);
 }
 #else	/* CONFIG_SERIAL_8250_DMA */
 static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}
-- 
2.17.1