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Subject[PATCH] [media] cx88: Fix unsafe locking in suspend-resume
Date
Legacy PCI suspend-resume handlers are called with interrupts enabled.
But cx8800_suspend/cx8800_resume and cx8802_suspend_common/cx8802_resume_common
use spin_lock/spin_unlock functions to acquire dev->slock, while the same lock is acquired in
the corresponding irq-handlers: cx8800_irq and cx8802_irq.
That means a deadlock is possible if an interrupt happens while suspend or resume owns the lock.

The patch replaces spin_lock/spin_unlock with spin_lock_irqsave/spin_unlock_irqrestore.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
drivers/media/pci/cx88/cx88-mpeg.c | 10 ++++++----
drivers/media/pci/cx88/cx88-video.c | 10 ++++++----
2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/media/pci/cx88/cx88-mpeg.c b/drivers/media/pci/cx88/cx88-mpeg.c
index c9d3182..c6cdbdb 100644
--- a/drivers/media/pci/cx88/cx88-mpeg.c
+++ b/drivers/media/pci/cx88/cx88-mpeg.c
@@ -532,16 +532,17 @@ static int cx8802_suspend_common(struct pci_dev *pci_dev, pm_message_t state)
{
struct cx8802_dev *dev = pci_get_drvdata(pci_dev);
struct cx88_core *core = dev->core;
+ unsigned long flags;

/* stop mpeg dma */
- spin_lock(&dev->slock);
+ spin_lock_irqsave(&dev->slock,flags);
if (!list_empty(&dev->mpegq.active)) {
dprintk( 2, "suspend\n" );
printk("%s: suspend mpeg\n", core->name);
cx8802_stop_dma(dev);
del_timer(&dev->mpegq.timeout);
}
- spin_unlock(&dev->slock);
+ spin_unlock_irqrestore(&dev->slock,flags);

/* FIXME -- shutdown device */
cx88_shutdown(dev->core);
@@ -558,6 +559,7 @@ static int cx8802_resume_common(struct pci_dev *pci_dev)
{
struct cx8802_dev *dev = pci_get_drvdata(pci_dev);
struct cx88_core *core = dev->core;
+ unsigned long flags;
int err;

if (dev->state.disabled) {
@@ -584,12 +586,12 @@ static int cx8802_resume_common(struct pci_dev *pci_dev)
cx88_reset(dev->core);

/* restart video+vbi capture */
- spin_lock(&dev->slock);
+ spin_lock_irqsave(&dev->slock,flags);
if (!list_empty(&dev->mpegq.active)) {
printk("%s: resume mpeg\n", core->name);
cx8802_restart_queue(dev,&dev->mpegq);
}
- spin_unlock(&dev->slock);
+ spin_unlock_irqrestore(&dev->slock,flags);

return 0;
}
diff --git a/drivers/media/pci/cx88/cx88-video.c b/drivers/media/pci/cx88/cx88-video.c
index bc78354..d72b403 100644
--- a/drivers/media/pci/cx88/cx88-video.c
+++ b/drivers/media/pci/cx88/cx88-video.c
@@ -1957,9 +1957,10 @@ static int cx8800_suspend(struct pci_dev *pci_dev, pm_message_t state)
{
struct cx8800_dev *dev = pci_get_drvdata(pci_dev);
struct cx88_core *core = dev->core;
+ unsigned long flags;

/* stop video+vbi capture */
- spin_lock(&dev->slock);
+ spin_lock_irqsave(&dev->slock,flags);
if (!list_empty(&dev->vidq.active)) {
printk("%s/0: suspend video\n", core->name);
stop_video_dma(dev);
@@ -1970,7 +1971,7 @@ static int cx8800_suspend(struct pci_dev *pci_dev, pm_message_t state)
cx8800_stop_vbi_dma(dev);
del_timer(&dev->vbiq.timeout);
}
- spin_unlock(&dev->slock);
+ spin_unlock_irqrestore(&dev->slock,flags);

if (core->ir)
cx88_ir_stop(core);
@@ -1989,6 +1990,7 @@ static int cx8800_resume(struct pci_dev *pci_dev)
{
struct cx8800_dev *dev = pci_get_drvdata(pci_dev);
struct cx88_core *core = dev->core;
+ unsigned long flags;
int err;

if (dev->state.disabled) {
@@ -2019,7 +2021,7 @@ static int cx8800_resume(struct pci_dev *pci_dev)
cx_set(MO_PCI_INTMSK, core->pci_irqmask);

/* restart video+vbi capture */
- spin_lock(&dev->slock);
+ spin_lock_irqsave(&dev->slock,flags);
if (!list_empty(&dev->vidq.active)) {
printk("%s/0: resume video\n", core->name);
restart_video_queue(dev,&dev->vidq);
@@ -2028,7 +2030,7 @@ static int cx8800_resume(struct pci_dev *pci_dev)
printk("%s/0: resume vbi\n", core->name);
cx8800_restart_vbi_queue(dev,&dev->vbiq);
}
- spin_unlock(&dev->slock);
+ spin_unlock_irqrestore(&dev->slock,flags);

return 0;
}
--
1.7.9.5


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