lkml.org 
[lkml]   [2009]   [Mar]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Revert "gro: Fix legacy path napi_complete crash",
    On Thu, Mar 26, 2009 at 10:41:29AM +0800, Herbert Xu wrote:
    ...
    > Yes this is why my original patch that started all this is broken.
    > However, this doesn't apply to my patch that open-codes __napi_complete.
    ...
    > This should work too. However, the fact that the following patch
    > is broken means that we have bigger problems.

    I agree. This should be effectively equal to the revert, so I guess
    Ingo probably hit some other bug btw.

    Jarek P.

    >
    > net: Fix netpoll lockup in legacy receive path
    >
    > When I fixed the GRO crash in the legacy receive path I used
    > napi_complete to replace __napi_complete. Unfortunately they're
    > not the same when NETPOLL is enabled, which may result in us
    > not calling __napi_complete at all.
    >
    > What's more, we really do need to keep the __napi_complete call
    > within the IRQ-off section since in theory an IRQ can occur in
    > between and fill up the backlog to the maximum, causing us to
    > lock up.
    >
    > This patch fixes this by essentially open-coding __napi_complete.
    >
    > Note we no longer need the memory barrier because this function
    > is per-cpu.
    >
    > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    >
    > diff --git a/net/core/dev.c b/net/core/dev.c
    > index e3fe5c7..2a7f6b3 100644
    > --- a/net/core/dev.c
    > +++ b/net/core/dev.c
    > @@ -2588,9 +2588,10 @@ static int process_backlog(struct napi_struct *napi, int quota)
    > local_irq_disable();
    > skb = __skb_dequeue(&queue->input_pkt_queue);
    > if (!skb) {
    > + list_del(&napi->poll_list);
    > + clear_bit(NAPI_STATE_SCHED, &napi->state);
    > local_irq_enable();
    > - napi_complete(napi);
    > - goto out;
    > + break;
    > }
    > local_irq_enable();
    >
    > @@ -2599,7 +2600,6 @@ static int process_backlog(struct napi_struct *napi, int quota)
    >
    > napi_gro_flush(napi);
    >
    > -out:
    > return work;
    > }
    >
    > Thanks,
    > --
    > Visit Openswan at http://www.openswan.org/
    > Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
    > Home Page: http://gondor.apana.org.au/~herbert/
    > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt


    \
     
     \ /
      Last update: 2009-03-26 08:41    [W:0.036 / U:60.660 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site