Commit 3d37ef41 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

media: cobalt: fix race condition in setting HPD 



The cobalt_s_bit_sysctrl reads the old register value over PCI,
then changes a bit and sets writes the new value to the register.

This is used among other things for setting the HPD output pin.

But if the HPD is changed for multiple inputs at the same time,
then this causes a race condition where a stale value is read.

Serialize this function with a mutex.

Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent b2cd0b31

drivers/media/pci/cobalt/cobalt-driver.c

+1 −0
Original line number Diff line number Diff line
@@ -667,6 +667,7 @@ static int cobalt_probe(struct pci_dev *pci_dev, 
		return -ENOMEM;

	cobalt->pci_dev = pci_dev;

	cobalt->instance = i;

	mutex_init(&cobalt->pci_lock);



	retval = v4l2_device_register(&pci_dev->dev, &cobalt->v4l2_dev);

	if (retval) {

drivers/media/pci/cobalt/cobalt-driver.h

+6 −1
Original line number Diff line number Diff line
@@ -251,6 +251,8 @@ struct cobalt { 
	int instance;

	struct pci_dev *pci_dev;

	struct v4l2_device v4l2_dev;

	/* serialize PCI access in cobalt_s_bit_sysctrl() */

	struct mutex pci_lock;



	void __iomem *bar0, *bar1;
@@ -320,10 +322,13 @@ static inline u32 cobalt_g_sysctrl(struct cobalt *cobalt) 
static inline void cobalt_s_bit_sysctrl(struct cobalt *cobalt,

					int bit, int val)

{

	u32 ctrl = cobalt_read_bar1(cobalt, COBALT_SYS_CTRL_BASE);

	u32 ctrl;



	mutex_lock(&cobalt->pci_lock);

	ctrl = cobalt_read_bar1(cobalt, COBALT_SYS_CTRL_BASE);

	cobalt_write_bar1(cobalt, COBALT_SYS_CTRL_BASE,

			(ctrl & ~(1UL << bit)) | (val << bit));

	mutex_unlock(&cobalt->pci_lock);

}



static inline u32 cobalt_g_sysstat(struct cobalt *cobalt)