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    SubjectRe: NOHZ: local_softirq_pending 08
    On 15.10.2009 19:53 Jarek Poplawski wrote:
    > Jarek Poplawski wrote, On 10/15/2009 01:40 PM:
    >> On 12-10-2009 13:25, Tilman Schmidt wrote:

    >>> I have encountered the message in the subject during a test of
    >>> the Gigaset CAPI driver, and would like to determine whether
    >>> it's a bug in the driver, a bug somewhere else, or no bug at
    >>> all. The test scenario was PPP over ISDN with pppd+capiplugin.
    >>> In an alternative scenario, also PPP over ISDN but with
    >>> smpppd+capidrv, the message did not occur.

    I'm sorry, I had confused the two cases. The message occurs in
    the smpppd+capidrv scenario, not with pppd+capiplugin.

    >>> Johannes' answer pointed me to the netif_rx() function.
    >>> The Gigaset driver itself doesn't call that function at all.
    >>> In the scenario where I saw the message, it was the SYNC_PPP
    >>> line discipline that did.

    This analysis was therefore wrong. It would be the netif_rx()
    call towards the end of isdn_ppp_push_higher() in
    drivers/isdn/i4l/isdn_ppp.c L1177.

    >> Anyway, I agree with Michael Buesch there is no reason to waste time
    >> for tracking all netif_rx vs netif_rx_ni uses, and it seems we could
    >> avoid it by using the "proper" version of raise_softirq_irqoff() in
    >> __napi_schedule(). Could anybody try if I'm not wrong?
    >> net/core/dev.c | 2 +-
    >> 1 files changed, 1 insertions(+), 1 deletions(-)
    >> diff --git a/net/core/dev.c b/net/core/dev.c
    >> index 28b0b9e..7fc4009 100644
    >> --- a/net/core/dev.c
    >> +++ b/net/core/dev.c
    >> @@ -2728,7 +2728,7 @@ void __napi_schedule(struct napi_struct *n)
    >> local_irq_save(flags);
    >> list_add_tail(&n->poll_list, &__get_cpu_var(softnet_data).poll_list);
    >> - __raise_softirq_irqoff(NET_RX_SOFTIRQ);
    >> + raise_softirq_irqoff(NET_RX_SOFTIRQ);
    >> local_irq_restore(flags);
    >> }
    >> EXPORT_SYMBOL(__napi_schedule);

    I have tested your patch and I can confirm that it fixes the messages.
    I have not noticed any ill effects.


    Tilman Schmidt E-Mail:
    Bonn, Germany
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