Re: [PATCH net-next v2 2/3] r8152: clear the flag of SCHEDULE_TASKLET in tasklet
From: David Miller <davem@davemloft.net>
Date: 2014-10-31 20:15:25
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From: Hayes Wang <redacted> Date: Fri, 31 Oct 2014 17:56:41 +0800
quoted hunk ↗ jump to hunk
Clear the flag of SCHEDULE_TASKLET in bottom_half() to avoid re-schedule the tasklet again by workqueue. Signed-off-by: Hayes Wang <redacted> --- drivers/net/usb/r8152.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index ff54098..670279a 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c@@ -1798,6 +1798,9 @@ static void bottom_half(unsigned long data) if (!netif_carrier_ok(tp->netdev)) return; + if (test_bit(SCHEDULE_TASKLET, &tp->flags)) + clear_bit(SCHEDULE_TASKLET, &tp->flags);
This is racey. If another thread of control sets the bit between the test and the clear, you will lose an event. It really never makes sense to work with atomic bitops in a non-atomic test-and-whatever manner like this, it's always a red flag and indicates you're doing something very wrong.