CAPI: Fix racy capi_read

capi_read still used interruptible_sleep_on, risking to miss a wakeup
this way. Convert it to wait_event_interruptible.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 12 deletions

diff --git a/drivers/isdn/capi/capi.c b/drivers/isdn/capi/capi.c
index f8f86602c57e..8abec9655e1a 100644
--- a/drivers/isdn/capi/capi.c
+++ b/drivers/isdn/capi/capi.c
@@ -657,24 +657,19 @@ capi_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
         struct capidev *cdev = (struct capidev *)file->private_data;
         struct sk_buff *skb;
         size_t copied;
+        int err;
 
         if (!cdev->ap.applid)
                 return -ENODEV;
 
-        if ((skb = skb_dequeue(&cdev->recvqueue)) == NULL) {
-
+        skb = skb_dequeue(&cdev->recvqueue);
+        if (!skb) {
                 if (file->f_flags & O_NONBLOCK)
                         return -EAGAIN;
-
-                for (;;) {
-                        interruptible_sleep_on(&cdev->recvwait);
-                        if ((skb = skb_dequeue(&cdev->recvqueue)) != NULL)
-                                break;
-                        if (signal_pending(current))
-                                break;
-                }
-                if (skb == NULL)
-                        return -ERESTARTNOHAND;
+                err = wait_event_interruptible(cdev->recvwait,
+                                (skb = skb_dequeue(&cdev->recvqueue)));
+                if (err)
+                        return err;
         }
         if (skb->len > count) {
                 skb_queue_head(&cdev->recvqueue, skb);