linux-kernel - [PATCH v2 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

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Date:   Wed, 23 Feb 2022 17:11:24 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Qing Wang <wangqing@...o.com>
Subject: [PATCH v2 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

The pci_get_slot() increases its reference count, the caller
must decrement the reference count by calling pci_dev_put().

Fixes: 90b9aacf912a ("serial: 8250_pci: add Intel Tangier support")
Fixes: f549e94effa1 ("serial: 8250_pci: add Intel Penwell ports")
Depends-on: d9eda9bab237 ("serial: 8250_pci: Intel MID UART support to its own driver")
Reported-by: Qing Wang <wangqing@...o.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
v2: rebased on top of the latest tty-linus
 drivers/tty/serial/8250/8250_mid.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mid.c b/drivers/tty/serial/8250/8250_mid.c
index 83592b51a996..a2a03acb04ad 100644
--- a/drivers/tty/serial/8250/8250_mid.c
+++ b/drivers/tty/serial/8250/8250_mid.c
@@ -73,6 +73,11 @@ static int pnw_setup(struct mid8250 *mid, struct uart_port *p)
 	return 0;
 }
 
+static void pnw_exit(struct mid8250 *mid)
+{
+	pci_dev_put(mid->dma_dev);
+}
+
 static int tng_handle_irq(struct uart_port *p)
 {
 	struct mid8250 *mid = p->private_data;
@@ -124,6 +129,11 @@ static int tng_setup(struct mid8250 *mid, struct uart_port *p)
 	return 0;
 }
 
+static void tng_exit(struct mid8250 *mid)
+{
+	pci_dev_put(mid->dma_dev);
+}
+
 static int dnv_handle_irq(struct uart_port *p)
 {
 	struct mid8250 *mid = p->private_data;
@@ -328,9 +338,9 @@ static int mid8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	pci_set_drvdata(pdev, mid);
 	return 0;
+
 err:
-	if (mid->board->exit)
-		mid->board->exit(mid);
+	mid->board->exit(mid);
 	return ret;
 }
 
@@ -340,8 +350,7 @@ static void mid8250_remove(struct pci_dev *pdev)
 
 	serial8250_unregister_port(mid->line);
 
-	if (mid->board->exit)
-		mid->board->exit(mid);
+	mid->board->exit(mid);
 }
 
 static const struct mid8250_board pnw_board = {
@@ -349,6 +358,7 @@ static const struct mid8250_board pnw_board = {
 	.freq = 50000000,
 	.base_baud = 115200,
 	.setup = pnw_setup,
+	.exit = pnw_exit,
 };
 
 static const struct mid8250_board tng_board = {
@@ -356,6 +366,7 @@ static const struct mid8250_board tng_board = {
 	.freq = 38400000,
 	.base_baud = 1843200,
 	.setup = tng_setup,
+	.exit = tng_exit,
 };
 
 static const struct mid8250_board dnv_board = {
-- 
2.34.1