usblp: mutex in usblp_check_status
Add a mutex to protect the ->statusbuf. Not really an issue, because CUPS
is single-threaded when it talks to the printer, but I feel safer this way.
This should be deadlock-free, but I kept this as a separate patch in case
someone ends running a git bisect.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 9696668..2c4a359 100644
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -345,16 +345,17 @@
unsigned char status, newerr = 0;
int error;
- error = usblp_read_status (usblp, usblp->statusbuf);
- if (error < 0) {
+ mutex_lock(&usblp->mut);
+ if ((error = usblp_read_status(usblp, usblp->statusbuf)) < 0) {
+ mutex_unlock(&usblp->mut);
if (printk_ratelimit())
printk(KERN_ERR
"usblp%d: error %d reading printer status\n",
usblp->minor, error);
return 0;
}
-
status = *usblp->statusbuf;
+ mutex_unlock(&usblp->mut);
if (~status & LP_PERRORP)
newerr = 3;