[media] DiBcom: protect the I2C bufer access

This patch protects the I2C buffer access in order to manage concurrent
access. This protection is done using mutex.
Furthermore, for the dib9000, if a pid filtering command is
received during the tuning, this pid filtering command is delayed to
avoid any concurrent access issue.

Cc: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: Florian Mickler <florian@mickler.org>
Cc: stable@kernel.org
Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <Patrick.Boettcher@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 30 insertions, 7 deletions

diff --git a/drivers/media/dvb/frontends/dib0070.c b/drivers/media/dvb/frontends/dib0070.c
index 1d47d4da7d4..dc1cb17a6ea 100644
--- a/drivers/media/dvb/frontends/dib0070.c
+++ b/drivers/media/dvb/frontends/dib0070.c
@@ -27,6 +27,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/mutex.h>
 
 #include "dvb_frontend.h"
 
@@ -78,10 +79,18 @@ struct dib0070_state {
 	struct i2c_msg msg[2];
 	u8 i2c_write_buffer[3];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
-static uint16_t dib0070_read_reg(struct dib0070_state *state, u8 reg)
+static u16 dib0070_read_reg(struct dib0070_state *state, u8 reg)
 {
+	u16 ret;
+
+	if (mutex_lock_interruptible(&state->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return 0;
+	}
+
 	state->i2c_write_buffer[0] = reg;
 
 	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
@@ -96,13 +105,23 @@ static uint16_t dib0070_read_reg(struct dib0070_state *state, u8 reg)
 
 	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0070 I2C read failed\n");
-		return 0;
-	}
-	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+		ret = 0;
+	} else
+		ret = (state->i2c_read_buffer[0] << 8)
+			| state->i2c_read_buffer[1];
+
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 static int dib0070_write_reg(struct dib0070_state *state, u8 reg, u16 val)
 {
+	int ret;
+
+	if (mutex_lock_interruptible(&state->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
 	state->i2c_write_buffer[0] = reg;
 	state->i2c_write_buffer[1] = val >> 8;
 	state->i2c_write_buffer[2] = val & 0xff;
@@ -115,9 +134,12 @@ static int dib0070_write_reg(struct dib0070_state *state, u8 reg, u16 val)
 
 	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0070 I2C write failed\n");
-		return -EREMOTEIO;
-	}
-	return 0;
+		ret = -EREMOTEIO;
+	} else
+		ret = 0;
+
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 #define HARD_RESET(state) do { \
@@ -734,6 +756,7 @@ struct dvb_frontend *dib0070_attach(struct dvb_frontend *fe, struct i2c_adapter
 	state->cfg = cfg;
 	state->i2c = i2c;
 	state->fe  = fe;
+	mutex_init(&state->i2c_buffer_lock);
 	fe->tuner_priv = state;
 
 	if (dib0070_reset(fe) != 0)