[media] radio-cadet: avoid interruptible_sleep_on race

interruptible_sleep_on is racy and going away. This replaces
one use in the radio-cadet driver with a wait_event_interruptible
call. Special care was taken that accesses to the rdsin and rdsout
indices are always done with dev->lock held.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --git a/drivers/media/radio/radio-cadet.c b/drivers/media/radio/radio-cadet.c
index 545c04cf722623851977b535cff71eac3e79f22f..d719e59e21790a5ea4353ca4ea9cc28350cb155d 100644 (file)
--- a/drivers/media/radio/radio-cadet.c
+++ b/drivers/media/radio/radio-cadet.c
@@ -270,6 +270,16 @@ reset_rds:
        outb(inb(dev->io + 1) & 0x7f, dev->io + 1);
 }
 
+static bool cadet_has_rds_data(struct cadet *dev)
+{
+       bool result;
+
+       mutex_lock(&dev->lock);
+       result = dev->rdsin != dev->rdsout;
+       mutex_unlock(&dev->lock);
+       return result;
+}
+
 
 static void cadet_handler(unsigned long data)
 {
@@ -279,13 +289,12 @@ static void cadet_handler(unsigned long data)
        if (mutex_trylock(&dev->lock)) {
                outb(0x3, dev->io);       /* Select RDS Decoder Control */
                if ((inb(dev->io + 1) & 0x20) != 0)
-                       printk(KERN_CRIT "cadet: RDS fifo overflow\n");
+                       pr_err("cadet: RDS fifo overflow\n");
                outb(0x80, dev->io);      /* Select RDS fifo */
+
                while ((inb(dev->io) & 0x80) != 0) {
                        dev->rdsbuf[dev->rdsin] = inb(dev->io + 1);
-                       if (dev->rdsin + 1 == dev->rdsout)
-                               printk(KERN_WARNING "cadet: RDS buffer overflow\n");
-                       else
+                       if (dev->rdsin + 1 != dev->rdsout)
                                dev->rdsin++;
                }
                mutex_unlock(&dev->lock);
@@ -294,7 +303,7 @@ static void cadet_handler(unsigned long data)
        /*
         * Service pending read
         */
-       if (dev->rdsin != dev->rdsout)
+       if (cadet_has_rds_data(dev))
                wake_up_interruptible(&dev->read_queue);
 
        /*
@@ -327,22 +336,21 @@ static ssize_t cadet_read(struct file *file, char __user *data, size_t count, lo
        mutex_lock(&dev->lock);
        if (dev->rdsstat == 0)
                cadet_start_rds(dev);
-       if (dev->rdsin == dev->rdsout) {
-               if (file->f_flags & O_NONBLOCK) {
-                       i = -EWOULDBLOCK;
-                       goto unlock;
-               }
-               mutex_unlock(&dev->lock);
-               interruptible_sleep_on(&dev->read_queue);
-               mutex_lock(&dev->lock);
-       }
+       mutex_unlock(&dev->lock);
+
+       if (!cadet_has_rds_data(dev) && (file->f_flags & O_NONBLOCK))
+               return -EWOULDBLOCK;
+       i = wait_event_interruptible(dev->read_queue, cadet_has_rds_data(dev));
+       if (i)
+               return i;
+
+       mutex_lock(&dev->lock);
        while (i < count && dev->rdsin != dev->rdsout)
                readbuf[i++] = dev->rdsbuf[dev->rdsout++];
+       mutex_unlock(&dev->lock);
 
        if (i && copy_to_user(data, readbuf, i))
-               i = -EFAULT;
-unlock:
-       mutex_unlock(&dev->lock);
+               return -EFAULT;
        return i;
 }
 
@@ -352,7 +360,7 @@ static int vidioc_querycap(struct file *file, void *priv,
 {
        strlcpy(v->driver, "ADS Cadet", sizeof(v->driver));
        strlcpy(v->card, "ADS Cadet", sizeof(v->card));
-       strlcpy(v->bus_info, "ISA", sizeof(v->bus_info));
+       strlcpy(v->bus_info, "ISA:radio-cadet", sizeof(v->bus_info));
        v->device_caps = V4L2_CAP_TUNER | V4L2_CAP_RADIO |
                          V4L2_CAP_READWRITE | V4L2_CAP_RDS_CAPTURE;
        v->capabilities = v->device_caps | V4L2_CAP_DEVICE_CAPS;
@@ -491,7 +499,7 @@ static unsigned int cadet_poll(struct file *file, struct poll_table_struct *wait
                        cadet_start_rds(dev);
                mutex_unlock(&dev->lock);
        }
-       if (dev->rdsin != dev->rdsout)
+       if (cadet_has_rds_data(dev))
                res |= POLLIN | POLLRDNORM;
        return res;
 }