[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>

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)

drivers/media/dvb/frontends/dib0090.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"
 
@@ -196,6 +197,7 @@ struct dib0090_state {
 	struct i2c_msg msg[2];
 	u8 i2c_write_buffer[3];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 struct dib0090_fw_state {
@@ -208,10 +210,18 @@ struct dib0090_fw_state {
 	struct i2c_msg msg;
 	u8 i2c_write_buffer[2];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 static u16 dib0090_read_reg(struct dib0090_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));
@@ -226,14 +236,24 @@ static u16 dib0090_read_reg(struct dib0090_state *state, u8 reg)
 
 	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0090 I2C read failed\n");
-		return 0;
-	}
+		ret = 0;
+	} else
+		ret = (state->i2c_read_buffer[0] << 8)
+			| state->i2c_read_buffer[1];
 
-	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 static int dib0090_write_reg(struct dib0090_state *state, u32 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 & 0xff;
 	state->i2c_write_buffer[1] = val >> 8;
 	state->i2c_write_buffer[2] = val & 0xff;
@@ -246,13 +266,23 @@ static int dib0090_write_reg(struct dib0090_state *state, u32 reg, u16 val)
 
 	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C write failed\n");
-		return -EREMOTEIO;
-	}
-	return 0;
+		ret = -EREMOTEIO;
+	} else
+		ret = 0;
+
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 static u16 dib0090_fw_read_reg(struct dib0090_fw_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, sizeof(struct i2c_msg));
@@ -262,13 +292,24 @@ static u16 dib0090_fw_read_reg(struct dib0090_fw_state *state, u8 reg)
 	state->msg.len = 2;
 	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 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 dib0090_fw_write_reg(struct dib0090_fw_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] = val >> 8;
 	state->i2c_write_buffer[1] = val & 0xff;
 
@@ -279,9 +320,12 @@ static int dib0090_fw_write_reg(struct dib0090_fw_state *state, u8 reg, u16 val)
 	state->msg.len = 2;
 	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 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 {  if (cfg->reset) {  if (cfg->sleep) cfg->sleep(fe, 0); msleep(10);  cfg->reset(fe, 1); msleep(10);  cfg->reset(fe, 0); msleep(10);  }  } while (0)
@@ -2440,6 +2484,7 @@ struct dvb_frontend *dib0090_register(struct dvb_frontend *fe, struct i2c_adapte
 	st->config = config;
 	st->i2c = i2c;
 	st->fe = fe;
+	mutex_init(&st->i2c_buffer_lock);
 	fe->tuner_priv = st;
 
 	if (config->wbd == NULL)
@@ -2471,6 +2516,7 @@ struct dvb_frontend *dib0090_fw_register(struct dvb_frontend *fe, struct i2c_ada
 	st->config = config;
 	st->i2c = i2c;
 	st->fe = fe;
+	mutex_init(&st->i2c_buffer_lock);
 	fe->tuner_priv = st;
 
 	if (dib0090_fw_reset_digital(fe, st->config) != 0)

drivers/media/dvb/frontends/dib7000m.c

@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/mutex.h>
 
 #include "dvb_frontend.h"
 
@@ -55,6 +56,7 @@ struct dib7000m_state {
 	struct i2c_msg msg[2];
 	u8 i2c_write_buffer[4];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 enum dib7000m_power_mode {
@@ -69,6 +71,13 @@ enum dib7000m_power_mode {
 
 static u16 dib7000m_read_word(struct dib7000m_state *state, u16 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 >> 8) | 0x80;
 	state->i2c_write_buffer[1] = reg & 0xff;
 
@@ -85,11 +94,21 @@ static u16 dib7000m_read_word(struct dib7000m_state *state, u16 reg)
 	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d",reg);
 
-	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	ret = (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	mutex_unlock(&state->i2c_buffer_lock);
+
+	return ret;
 }
 
 static int dib7000m_write_word(struct dib7000m_state *state, u16 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 >> 8) & 0xff;
 	state->i2c_write_buffer[1] = reg & 0xff;
 	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
@@ -101,7 +120,10 @@ static int dib7000m_write_word(struct dib7000m_state *state, u16 reg, u16 val)
 	state->msg[0].buf = state->i2c_write_buffer;
 	state->msg[0].len = 4;
 
-	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
+	ret = (i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ?
+			-EREMOTEIO : 0);
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 static void dib7000m_write_tab(struct dib7000m_state *state, u16 *buf)
 {
@@ -1385,6 +1407,7 @@ struct dvb_frontend * dib7000m_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr,
 	demod                   = &st->demod;
 	demod->demodulator_priv = st;
 	memcpy(&st->demod.ops, &dib7000m_ops, sizeof(struct dvb_frontend_ops));
+	mutex_init(&st->i2c_buffer_lock);
 
 	st->timf_default = cfg->bw->timf;
 

drivers/media/dvb/frontends/dib7000p.c

@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/mutex.h>
 
 #include "dvb_math.h"
 #include "dvb_frontend.h"
@@ -68,6 +69,7 @@ struct dib7000p_state {
 	struct i2c_msg msg[2];
 	u8 i2c_write_buffer[4];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 enum dib7000p_power_mode {
@@ -81,6 +83,13 @@ static int dib7090_set_diversity_in(struct dvb_frontend *fe, int onoff);
 
 static u16 dib7000p_read_word(struct dib7000p_state *state, u16 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 >> 8;
 	state->i2c_write_buffer[1] = reg & 0xff;
 
@@ -97,11 +106,20 @@ static u16 dib7000p_read_word(struct dib7000p_state *state, u16 reg)
 	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	ret = (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 static int dib7000p_write_word(struct dib7000p_state *state, u16 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 >> 8) & 0xff;
 	state->i2c_write_buffer[1] = reg & 0xff;
 	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
@@ -113,7 +131,10 @@ static int dib7000p_write_word(struct dib7000p_state *state, u16 reg, u16 val)
 	state->msg[0].buf = state->i2c_write_buffer;
 	state->msg[0].len = 4;
 
-	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
+	ret = (i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ?
+			-EREMOTEIO : 0);
+	mutex_unlock(&state->i2c_buffer_lock);
+	return ret;
 }
 
 static void dib7000p_write_tab(struct dib7000p_state *state, u16 * buf)
@@ -1646,6 +1667,7 @@ int dib7000p_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 defau
 		return -ENOMEM;
 
 	dpst->i2c_adap = i2c;
+	mutex_init(&dpst->i2c_buffer_lock);
 
 	for (k = no_of_demods - 1; k >= 0; k--) {
 		dpst->cfg = cfg[k];
@@ -2324,6 +2346,7 @@ struct dvb_frontend *dib7000p_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr,
 	demod = &st->demod;
 	demod->demodulator_priv = st;
 	memcpy(&st->demod.ops, &dib7000p_ops, sizeof(struct dvb_frontend_ops));
+	mutex_init(&st->i2c_buffer_lock);
 
 	dib7000p_write_word(st, 1287, 0x0003);	/* sram lead in, rdy */
 
@@ -2333,8 +2356,9 @@ struct dvb_frontend *dib7000p_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr,
 	st->version = dib7000p_read_word(st, 897);
 
 	/* FIXME: make sure the dev.parent field is initialized, or else
-		request_firmware() will hit an OOPS (this should be moved somewhere
-		more common) */
+	   request_firmware() will hit an OOPS (this should be moved somewhere
+	   more common) */
+	st->i2c_master.gated_tuner_i2c_adap.dev.parent = i2c_adap->dev.parent;
 
 	/* FIXME: make sure the dev.parent field is initialized, or else
 	   request_firmware() will hit an OOPS (this should be moved somewhere

drivers/media/dvb/frontends/dib8000.c

@@ -10,6 +10,8 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
+#include <linux/mutex.h>
+
 #include "dvb_math.h"
 
 #include "dvb_frontend.h"
@@ -37,6 +39,7 @@ struct i2c_device {
 	u8 addr;
 	u8 *i2c_write_buffer;
 	u8 *i2c_read_buffer;
+	struct mutex *i2c_buffer_lock;
 };
 
 struct dib8000_state {
@@ -77,6 +80,7 @@ struct dib8000_state {
 	struct i2c_msg msg[2];
 	u8 i2c_write_buffer[4];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 enum dib8000_power_mode {
@@ -86,24 +90,39 @@ enum dib8000_power_mode {
 
 static u16 dib8000_i2c_read16(struct i2c_device *i2c, u16 reg)
 {
+	u16 ret;
 	struct i2c_msg msg[2] = {
-		{.addr = i2c->addr >> 1, .flags = 0,
-			.buf = i2c->i2c_write_buffer, .len = 2},
-		{.addr = i2c->addr >> 1, .flags = I2C_M_RD,
-			.buf = i2c->i2c_read_buffer, .len = 2},
+		{.addr = i2c->addr >> 1, .flags = 0, .len = 2},
+		{.addr = i2c->addr >> 1, .flags = I2C_M_RD, .len = 2},
 	};
 
+	if (mutex_lock_interruptible(i2c->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return 0;
+	}
+
+	msg[0].buf    = i2c->i2c_write_buffer;
 	msg[0].buf[0] = reg >> 8;
 	msg[0].buf[1] = reg & 0xff;
+	msg[1].buf    = i2c->i2c_read_buffer;
 
 	if (i2c_transfer(i2c->adap, msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (msg[1].buf[0] << 8) | msg[1].buf[1];
+	ret = (msg[1].buf[0] << 8) | msg[1].buf[1];
+	mutex_unlock(i2c->i2c_buffer_lock);
+	return ret;
 }
 
 static u16 dib8000_read_word(struct dib8000_state *state, u16 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 >> 8;
 	state->i2c_write_buffer[1] = reg & 0xff;
 
@@ -120,7 +139,10 @@ static u16 dib8000_read_word(struct dib8000_state *state, u16 reg)
 	if (i2c_transfer(state->i2c.adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	ret = (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
+	mutex_unlock(&state->i2c_buffer_lock);
+
+	return ret;
 }
 
 static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
@@ -135,22 +157,35 @@ static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
 
 static int dib8000_i2c_write16(struct i2c_device *i2c, u16 reg, u16 val)
 {
-	struct i2c_msg msg = {.addr = i2c->addr >> 1, .flags = 0,
-		.buf = i2c->i2c_write_buffer, .len = 4};
+	struct i2c_msg msg = {.addr = i2c->addr >> 1, .flags = 0, .len = 4};
 	int ret = 0;
 
+	if (mutex_lock_interruptible(i2c->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
+
+	msg.buf    = i2c->i2c_write_buffer;
 	msg.buf[0] = (reg >> 8) & 0xff;
 	msg.buf[1] = reg & 0xff;
 	msg.buf[2] = (val >> 8) & 0xff;
 	msg.buf[3] = val & 0xff;
 
 	ret = i2c_transfer(i2c->adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	mutex_unlock(i2c->i2c_buffer_lock);
 
 	return ret;
 }
 
 static int dib8000_write_word(struct dib8000_state *state, u16 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 >> 8) & 0xff;
 	state->i2c_write_buffer[1] = reg & 0xff;
 	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
@@ -162,7 +197,11 @@ static int dib8000_write_word(struct dib8000_state *state, u16 reg, u16 val)
 	state->msg[0].buf = state->i2c_write_buffer;
 	state->msg[0].len = 4;
 
-	return i2c_transfer(state->i2c.adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
+	ret = (i2c_transfer(state->i2c.adap, state->msg, 1) != 1 ?
+			-EREMOTEIO : 0);
+	mutex_unlock(&state->i2c_buffer_lock);
+
+	return ret;
 }
 
 static const s16 coeff_2k_sb_1seg_dqpsk[8] = {
@@ -2434,8 +2473,15 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 	if (!client.i2c_read_buffer) {
 		dprintk("%s: not enough memory", __func__);
 		ret = -ENOMEM;
-		goto error_memory;
+		goto error_memory_read;
+	}
+	client.i2c_buffer_lock = kzalloc(sizeof(struct mutex), GFP_KERNEL);
+	if (!client.i2c_buffer_lock) {
+		dprintk("%s: not enough memory", __func__);
+		ret = -ENOMEM;
+		goto error_memory_lock;
 	}
+	mutex_init(client.i2c_buffer_lock);
 
 	for (k = no_of_demods - 1; k >= 0; k--) {
 		/* designated i2c address */
@@ -2476,8 +2522,10 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 	}
 
 error:
+	kfree(client.i2c_buffer_lock);
+error_memory_lock:
 	kfree(client.i2c_read_buffer);
-error_memory:
+error_memory_read:
 	kfree(client.i2c_write_buffer);
 
 	return ret;
@@ -2581,6 +2629,8 @@ struct dvb_frontend *dib8000_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr, s
 	state->i2c.addr = i2c_addr;
 	state->i2c.i2c_write_buffer = state->i2c_write_buffer;
 	state->i2c.i2c_read_buffer = state->i2c_read_buffer;
+	mutex_init(&state->i2c_buffer_lock);
+	state->i2c.i2c_buffer_lock = &state->i2c_buffer_lock;
 	state->gpio_val = cfg->gpio_val;
 	state->gpio_dir = cfg->gpio_dir;
 

drivers/media/dvb/frontends/dibx000_common.c

 #include <linux/i2c.h>
+#include <linux/mutex.h>
 
 #include "dibx000_common.h"
 
@@ -10,6 +11,13 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 
 static int dibx000_write_word(struct dibx000_i2c_master *mst, u16 reg, u16 val)
 {
+	int ret;
+
+	if (mutex_lock_interruptible(&mst->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
+
 	mst->i2c_write_buffer[0] = (reg >> 8) & 0xff;
 	mst->i2c_write_buffer[1] = reg & 0xff;
 	mst->i2c_write_buffer[2] = (val >> 8) & 0xff;
@@ -21,11 +29,21 @@ static int dibx000_write_word(struct dibx000_i2c_master *mst, u16 reg, u16 val)
 	mst->msg[0].buf = mst->i2c_write_buffer;
 	mst->msg[0].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, mst->msg, 1) != 1 ? -EREMOTEIO : 0;
+	ret = i2c_transfer(mst->i2c_adap, mst->msg, 1) != 1 ? -EREMOTEIO : 0;
+	mutex_unlock(&mst->i2c_buffer_lock);
+
+	return ret;
 }
 
 static u16 dibx000_read_word(struct dibx000_i2c_master *mst, u16 reg)
 {
+	u16 ret;
+
+	if (mutex_lock_interruptible(&mst->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return 0;
+	}
+
 	mst->i2c_write_buffer[0] = reg >> 8;
 	mst->i2c_write_buffer[1] = reg & 0xff;
 
@@ -42,7 +60,10 @@ static u16 dibx000_read_word(struct dibx000_i2c_master *mst, u16 reg)
 	if (i2c_transfer(mst->i2c_adap, mst->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (mst->i2c_read_buffer[0] << 8) | mst->i2c_read_buffer[1];
+	ret = (mst->i2c_read_buffer[0] << 8) | mst->i2c_read_buffer[1];
+	mutex_unlock(&mst->i2c_buffer_lock);
+
+	return ret;
 }
 
 static int dibx000_is_i2c_done(struct dibx000_i2c_master *mst)
@@ -257,6 +278,7 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
+	int ret;
 
 	if (num > 32) {
 		dprintk("%s: too much I2C message to be transmitted (%i).\
@@ -264,10 +286,15 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 		return -ENOMEM;
 	}
 
-	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
-
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_GPIO_6_7);
 
+	if (mutex_lock_interruptible(&mst->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
+
 	/* open the gate */
 	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
 	mst->msg[0].addr = mst->i2c_addr;
@@ -282,7 +309,11 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
 	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
+	ret = (i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ?
+			num : -EIO);
+
+	mutex_unlock(&mst->i2c_buffer_lock);
+	return ret;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_gpio67_algo = {
@@ -294,6 +325,7 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
+	int ret;
 
 	if (num > 32) {
 		dprintk("%s: too much I2C message to be transmitted (%i).\
@@ -301,10 +333,14 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 		return -ENOMEM;
 	}
 
-	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
-
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_TUNER);
 
+	if (mutex_lock_interruptible(&mst->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
+
 	/* open the gate */
 	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
 	mst->msg[0].addr = mst->i2c_addr;
@@ -319,7 +355,10 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
 	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
+	ret = (i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ?
+			num : -EIO);
+	mutex_unlock(&mst->i2c_buffer_lock);
+	return ret;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_tuner_algo = {
@@ -390,8 +429,18 @@ static int i2c_adapter_init(struct i2c_adapter *i2c_adap,
 int dibx000_init_i2c_master(struct dibx000_i2c_master *mst, u16 device_rev,
 				struct i2c_adapter *i2c_adap, u8 i2c_addr)
 {
-	u8 tx[4];
-	struct i2c_msg m = {.addr = i2c_addr >> 1,.buf = tx,.len = 4 };
+	int ret;
+
+	mutex_init(&mst->i2c_buffer_lock);
+	if (mutex_lock_interruptible(&mst->i2c_buffer_lock) < 0) {
+		dprintk("could not acquire lock");
+		return -EINVAL;
+	}
+	memset(mst->msg, 0, sizeof(struct i2c_msg));
+	mst->msg[0].addr = i2c_addr >> 1;
+	mst->msg[0].flags = 0;
+	mst->msg[0].buf = mst->i2c_write_buffer;
+	mst->msg[0].len = 4;
 
 	mst->device_rev = device_rev;
 	mst->i2c_adap = i2c_adap;
@@ -431,9 +480,12 @@ int dibx000_init_i2c_master(struct dibx000_i2c_master *mst, u16 device_rev,
 				"DiBX000: could not initialize the master i2c_adapter\n");
 
 	/* initialize the i2c-master by closing the gate */
-	dibx000_i2c_gate_ctrl(mst, tx, 0, 0);
+	dibx000_i2c_gate_ctrl(mst, mst->i2c_write_buffer, 0, 0);
+
+	ret = (i2c_transfer(i2c_adap, mst->msg, 1) == 1);
+	mutex_unlock(&mst->i2c_buffer_lock);
 
-	return i2c_transfer(i2c_adap, &m, 1) == 1;
+	return ret;
 }
 
 EXPORT_SYMBOL(dibx000_init_i2c_master);

drivers/media/dvb/frontends/dibx000_common.h

@@ -33,6 +33,7 @@ struct dibx000_i2c_master {
 	struct i2c_msg msg[34];
 	u8 i2c_write_buffer[8];
 	u8 i2c_read_buffer[2];
+	struct mutex i2c_buffer_lock;
 };
 
 extern int dibx000_init_i2c_master(struct dibx000_i2c_master *mst,