This is a note to let you know that I've just added the patch titled
media: cobalt: fix race condition in setting HPD
to the 5.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
media-cobalt-fix-race-condition-in-setting-hpd.patch
and it can be found in the queue-5.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 45105385d04a2184c5a05f8a5b59e4f50e270f9a
Author: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Date: Fri Apr 23 10:00:49 2021 +0200
media: cobalt: fix race condition in setting HPD
[ Upstream commit 3d37ef41bed0854805ab9af22c422267510e1344 ]
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: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/media/pci/cobalt/cobalt-driver.c b/drivers/media/pci/cobalt/cobalt-driver.c
index 0695078ef812..1bd8bbe57a30 100644
--- a/drivers/media/pci/cobalt/cobalt-driver.c
+++ b/drivers/media/pci/cobalt/cobalt-driver.c
@@ -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) {
diff --git a/drivers/media/pci/cobalt/cobalt-driver.h b/drivers/media/pci/cobalt/cobalt-driver.h
index bca68572b324..12c33e035904 100644
--- a/drivers/media/pci/cobalt/cobalt-driver.h
+++ b/drivers/media/pci/cobalt/cobalt-driver.h
@@ -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)
