ieee1394: raw1394: make write() thread-safe
Application programs should use a libraw1394 handle only in a single
thread. The raw1394 driver was apparently relying on this, because it
did nothing to protect its fi->state variable from corruption due to
concurrent accesses.
We now serialize the fi->state accesses. This affects the write() path.
We re-use the state_mutex which was introduced to protect fi->iso_state
accesses in the ioctl() path. These paths and accesses are independent
of each other, hence separate mutexes could be used. But I don't see
much benefit in that.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/drivers/ieee1394/raw1394.c b/drivers/ieee1394/raw1394.c
index d159442..2cf4ae7 100644
--- a/drivers/ieee1394/raw1394.c
+++ b/drivers/ieee1394/raw1394.c
@@ -2268,6 +2268,8 @@
return -EFAULT;
}
+ mutex_lock(&fi->state_mutex);
+
switch (fi->state) {
case opened:
retval = state_opened(fi, req);
@@ -2282,6 +2284,8 @@
break;
}
+ mutex_unlock(&fi->state_mutex);
+
if (retval < 0) {
free_pending_request(req);
} else {