i2c-algo-pcf: Handle timeout correctly

With a postfix decrement these timeouts reach -1 rather than 0, but after the
loop it is tested whether they have become 0.

As pointed out by Jean Delvare, the msg_num should be tested before the timeout.
With the current order, you could exit with a timeout error while all the
messages were successfully transferred.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Eric Brower <ebrower@gmail.com>

1 files changed, 10 insertions, 8 deletions

diff --git a/drivers/i2c/algos/i2c-algo-pcf.c b/drivers/i2c/algos/i2c-algo-pcf.c
index 5906986d013b..65a769f3ae79 100644
--- a/drivers/i2c/algos/i2c-algo-pcf.c
+++ b/drivers/i2c/algos/i2c-algo-pcf.c
@@ -115,15 +115,17 @@ static int wait_for_bb(struct i2c_algo_pcf_data *adap)
 
         status = get_pcf(adap, 1);
 
-        while (timeout-- && !(status & I2C_PCF_BB)) {
+        while (!(status & I2C_PCF_BB) && --timeout) {
                 udelay(100); /* wait for 100 us */
                 status = get_pcf(adap, 1);
         }
 
-        if (timeout <= 0)
+        if (timeout == 0) {
                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
+                return -ETIMEDOUT;
+        }
 
-        return timeout <= 0;
+        return 0;
 }
 
 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
@@ -133,7 +135,7 @@ static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
 
         *status = get_pcf(adap, 1);
 
-        while (timeout-- && (*status & I2C_PCF_PIN)) {
+        while ((*status & I2C_PCF_PIN) && --timeout) {
                 adap->waitforpin(adap->data);
                 *status = get_pcf(adap, 1);
         }
@@ -142,10 +144,10 @@ static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
                 return -EINTR;
         }
 
-        if (timeout <= 0)
-                return -1;
-        else
-                return 0;
+        if (timeout == 0)
+                return -ETIMEDOUT;
+
+        return 0;
 }
 
 /*