Messages in this thread Patch in this message | | | Date | Tue, 16 Oct 2007 17:55:55 -0400 | From | Jeff Garzik <> | Subject | [PATCH/RFA] sch_generic: fix carrier-on bug? |
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While looking at a net driver with the following construct,
if (!netif_carrier_ok(dev)) netif_carrier_on(dev);
it stuck me that the netif_carrier_ok() check was redundant, since netif_carrier_on() checks bit __LINK_STATE_NOCARRIER anyway. This is the same reason why netif_queue_stopped() need not be called prior to netif_wake_queue().
This is true, but there is however an unwanted side effect from assuming that netif_carrier_on() can be called multiple times: it touches the watchdog, regardless of pre-existing carrier state.
The fix: move watchdog-up inside the bit-cleared code path.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com> ---
This looks like an obvious bug fix to me, but I found it by reading code rather than hitting it in the field. Review appreciated.
net/sched/sch_generic.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index 95ae119..e01d576 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -249,10 +249,11 @@ static void dev_watchdog_down(struct net_device *dev) */ void netif_carrier_on(struct net_device *dev) { - if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) + if (test_and_clear_bit(__LINK_STATE_NOCARRIER, &dev->state)) { linkwatch_fire_event(dev); - if (netif_running(dev)) - __netdev_watchdog_up(dev); + if (netif_running(dev)) + __netdev_watchdog_up(dev); + } } /** - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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