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Subject[patch] media video cx23888 driver: fix possible races using new kfifo_API kfifo_reset()
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Fix the cx23888 driver to use the new kfifo API. Using kfifo_reset() may
result in a possible race conditions. This patch fix it by using
spinlock around the kfifo_reset() function.

The patch-set is against mm tree from 11-Dec-2009

Greetings,
Stefani

Signed-off-by: Stefani Seibold <stefani@seibold.net>
---
cx23888-ir.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- mmotm.orig/drivers/media/video/cx23885/cx23888-ir.c 2009-12-18 22:57:13.588337402 +0100
+++ mmotm/drivers/media/video/cx23885/cx23888-ir.c 2009-12-18 23:15:14.651365720 +0100
@@ -519,6 +519,7 @@ static int cx23888_ir_irq_handler(struct
{
struct cx23888_ir_state *state = to_state(sd);
struct cx23885_dev *dev = state->dev;
+ unsigned long flags;

u32 cntrl = cx23888_ir_read4(dev, CX23888_IR_CNTRL_REG);
u32 irqen = cx23888_ir_read4(dev, CX23888_IR_IRQEN_REG);
@@ -629,8 +630,11 @@ static int cx23888_ir_irq_handler(struct
cx23888_ir_write4(dev, CX23888_IR_CNTRL_REG, cntrl);
*handled = true;
}
+
+ spin_lock_irqsave(&state->rx_kfifo_lock, flags);
if (kfifo_len(&state->rx_kfifo) >= CX23888_IR_RX_KFIFO_SIZE / 2)
events |= V4L2_SUBDEV_IR_RX_FIFO_SERVICE_REQ;
+ spin_unlock_irqrestore(&state->rx_kfifo_lock, flags);

if (events)
v4l2_subdev_notify(sd, V4L2_SUBDEV_IR_RX_NOTIFY, &events);
@@ -783,7 +787,12 @@ static int cx23888_ir_rx_s_parameters(st
o->interrupt_enable = p->interrupt_enable;
o->enable = p->enable;
if (p->enable) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&state->rx_kfifo_lock, flags);
kfifo_reset(&state->rx_kfifo);
+ /* reset tx_fifo too if there is one... */
+ spin_unlock_irqrestore(&state->rx_kfifo_lock, flags);
if (p->interrupt_enable)
irqenable_rx(dev, IRQEN_RSE | IRQEN_RTE | IRQEN_ROE);
control_rx_enable(dev, p->enable);



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