[PATCH 4.10 15/93] staging: comedi: jr3_pci: cope with jiffies wraparound

From: Greg Kroah-Hartman
Date: Thu May 18 2017 - 07:49:39 EST

4.10-stable review patch. If anyone has any objections, please let me know.


From: Ian Abbott <abbotti@xxxxxxxxx>

commit 8ec04a491825e08068e92bed0bba7821893b6433 upstream.

The timer expiry routine `jr3_pci_poll_dev()` checks for expiry by
checking whether the absolute value of `jiffies` (stored in local
variable `now`) is greater than the expected expiry time in jiffy units.
This will fail when `jiffies` wraps around. Also, it seems to make
sense to handle the expiry one jiffy earlier than the current test. Use
`time_after_eq()` to check for expiry.

Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/staging/comedi/drivers/jr3_pci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/staging/comedi/drivers/jr3_pci.c
+++ b/drivers/staging/comedi/drivers/jr3_pci.c
@@ -611,7 +611,7 @@ static void jr3_pci_poll_dev(unsigned lo
s = &dev->subdevices[i];
spriv = s->private;

- if (now > spriv->next_time_min) {
+ if (time_after_eq(now, spriv->next_time_min)) {
struct jr3_pci_poll_delay sub_delay;

sub_delay = jr3_pci_poll_subdevice(s);