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usblp: mutex in usblp_check_status

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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>
This commit is contained in:
Pete Zaitcev 2007-08-13 22:50:13 -07:00 committed by Greg Kroah-Hartman
parent 7b5cd5fefb
commit fc401e697f
1 changed files with 4 additions and 3 deletions
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7
drivers/usb/class/usblp.c
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@ -345,16 +345,17 @@ static int usblp_check_status(struct usblp *usblp, int err)
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;