[PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Andy Shevchenko]

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@vivo.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 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 efa0515139f8..e6c1791609dd 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;
@@ -330,9 +340,9 @@ 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;
 }
 
@@ -342,8 +352,7 @@ 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 = {
@@ -351,6 +360,7 @@ 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 = {
@@ -358,6 +368,7 @@ 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

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Jiri Slaby]

On 15. 02. 22, 11:09, Andy Shevchenko wrote:
> The pci_get_slot() increases its reference count, the caller
> must decrement the reference count by calling pci_dev_put().

And what about the -EINVAL case?

> 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@vivo.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>   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 efa0515139f8..e6c1791609dd 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;
> @@ -330,9 +340,9 @@ 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;
>   }
>   
> @@ -342,8 +352,7 @@ 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 = {
> @@ -351,6 +360,7 @@ 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 = {
> @@ -358,6 +368,7 @@ 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 = {


-- 
js
suse labs

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Andy Shevchenko]

On Tue, Feb 15, 2022 at 11:11:41AM +0100, Jiri Slaby wrote:
> On 15. 02. 22, 11:09, Andy Shevchenko wrote:
> > The pci_get_slot() increases its reference count, the caller
> > must decrement the reference count by calling pci_dev_put().

> And what about the -EINVAL case?

What about it? The ->probe() calls ->exit() in its error path.
Or did I miss something?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Andy Shevchenko]

On Tue, Feb 15, 2022 at 12:29:49PM +0200, Andy Shevchenko wrote:
> On Tue, Feb 15, 2022 at 11:11:41AM +0100, Jiri Slaby wrote:
> > On 15. 02. 22, 11:09, Andy Shevchenko wrote:
> > > The pci_get_slot() increases its reference count, the caller
> > > must decrement the reference count by calling pci_dev_put().
> 
> > And what about the -EINVAL case?
> 
> What about it? The ->probe() calls ->exit() in its error path.
> Or did I miss something?

Or you mean that we call pci_dev_put() on NULL pointer?
This is completely valid case and handled in the callee.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Jiri Slaby]

On 15. 02. 22, 11:31, Andy Shevchenko wrote:
> On Tue, Feb 15, 2022 at 12:29:49PM +0200, Andy Shevchenko wrote:
>> On Tue, Feb 15, 2022 at 11:11:41AM +0100, Jiri Slaby wrote:
>>> On 15. 02. 22, 11:09, Andy Shevchenko wrote:
>>>> The pci_get_slot() increases its reference count, the caller
>>>> must decrement the reference count by calling pci_dev_put().
>>
>>> And what about the -EINVAL case?
>>
>> What about it? The ->probe() calls ->exit() in its error path.
>> Or did I miss something?
> 
> Or you mean that we call pci_dev_put() on NULL pointer?
> This is completely valid case and handled in the callee.

No, I mixed up patches :P. This was meant as a comment to
"serial: 8250_lpss: Balance reference count for PCI DMA device"

byt_serial_exit() isn't called when byt_serial_setup() fails with EINVAL 
if I'm looking correctly.

thanks,
-- 
js
suse labs

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Andy Shevchenko]

On Tue, Feb 15, 2022 at 12:08:26PM +0100, Jiri Slaby wrote:
> On 15. 02. 22, 11:31, Andy Shevchenko wrote:
> > On Tue, Feb 15, 2022 at 12:29:49PM +0200, Andy Shevchenko wrote:
> > > On Tue, Feb 15, 2022 at 11:11:41AM +0100, Jiri Slaby wrote:
> > > > On 15. 02. 22, 11:09, Andy Shevchenko wrote:
> > > > > The pci_get_slot() increases its reference count, the caller
> > > > > must decrement the reference count by calling pci_dev_put().
> > > 
> > > > And what about the -EINVAL case?
> > > 
> > > What about it? The ->probe() calls ->exit() in its error path.
> > > Or did I miss something?
> > 
> > Or you mean that we call pci_dev_put() on NULL pointer?
> > This is completely valid case and handled in the callee.
> 
> No, I mixed up patches :P. This was meant as a comment to
> "serial: 8250_lpss: Balance reference count for PCI DMA device"
> 
> byt_serial_exit() isn't called when byt_serial_setup() fails with EINVAL if
> I'm looking correctly.

I see now, thanks for catching this!
I will send a v2 soon.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] serial: 8250_mid: Balance reference count for PCI DMA device

[Andy Shevchenko]

On Tue, Feb 15, 2022 at 02:25:42PM +0200, Andy Shevchenko wrote:
> On Tue, Feb 15, 2022 at 12:08:26PM +0100, Jiri Slaby wrote:
> > On 15. 02. 22, 11:31, Andy Shevchenko wrote:

...

> > No, I mixed up patches :P. This was meant as a comment to
> > "serial: 8250_lpss: Balance reference count for PCI DMA device"
> > 
> > byt_serial_exit() isn't called when byt_serial_setup() fails with EINVAL if
> > I'm looking correctly.
> 
> I see now, thanks for catching this!
> I will send a v2 soon.

What do you think about this patch? Can you give your tag if the code is
looking good?

-- 
With Best Regards,
Andy Shevchenko