isdn: divert, hysdn: fix interruptible_sleep_on race

These two drivers use identical code for their procfs status
file handling, which contains a small race against status
data becoming available while reading the file.

This uses wait_event_interruptible instead to fix this
particular race and eventually get rid of all sleep_on
instances. There seems to be another race involving
multiple concurrent readers of the same procfs file, which
I don't try to fix here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/isdn/divert/divert_procfs.c b/drivers/isdn/divert/divert_procfs.c
index fb4f1bac0133..1c5dc345e7c5 100644
--- a/drivers/isdn/divert/divert_procfs.c
+++ b/drivers/isdn/divert/divert_procfs.c
@@ -86,12 +86,13 @@ isdn_divert_read(struct file *file, char __user *buf, size_t count, loff_t *off)
         struct divert_info *inf;
         int len;
 
-        if (!*((struct divert_info **) file->private_data)) {
+        if (!(inf = *((struct divert_info **) file->private_data))) {
                 if (file->f_flags & O_NONBLOCK)
                         return -EAGAIN;
-                interruptible_sleep_on(&(rd_queue));
+                wait_event_interruptible(rd_queue, (inf =
+                        *((struct divert_info **) file->private_data)));
         }
-        if (!(inf = *((struct divert_info **) file->private_data)))
+        if (!inf)
                 return (0);
 
         inf->usage_cnt--;       /* new usage count */