> -----Original Message----- > From: Wei Liu [mailto:[email protected]] > Sent: 21 June 2017 10:21 > To: [email protected] > Cc: Xen-devel <[email protected]>; Paul Durrant > <[email protected]>; David Miller <[email protected]>; jean- > [email protected]; Wei Liu <[email protected]> > Subject: [PATCH net] xen-netback: correctly schedule rate-limited queues > > Add a flag to indicate if a queue is rate-limited. Test the flag in > NAPI poll handler and avoid rescheduling the queue if true, otherwise > we risk locking up the host. The rescheduling will be done in the > timer callback function. > > Reported-by: Jean-Louis Dupond <[email protected]> > Signed-off-by: Wei Liu <[email protected]> > Tested-by: Jean-Louis Dupond <[email protected]>
Reviewed-by: Paul Durrant <[email protected]> > --- > drivers/net/xen-netback/common.h | 1 + > drivers/net/xen-netback/interface.c | 6 +++++- > drivers/net/xen-netback/netback.c | 6 +++++- > 3 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen- > netback/common.h > index 530586be05b4..5b1d2e8402d9 100644 > --- a/drivers/net/xen-netback/common.h > +++ b/drivers/net/xen-netback/common.h > @@ -199,6 +199,7 @@ struct xenvif_queue { /* Per-queue data for xenvif */ > unsigned long remaining_credit; > struct timer_list credit_timeout; > u64 credit_window_start; > + bool rate_limited; > > /* Statistics */ > struct xenvif_stats stats; > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen- > netback/interface.c > index 8397f6c92451..e322a862ddfe 100644 > --- a/drivers/net/xen-netback/interface.c > +++ b/drivers/net/xen-netback/interface.c > @@ -106,7 +106,11 @@ static int xenvif_poll(struct napi_struct *napi, int > budget) > > if (work_done < budget) { > napi_complete_done(napi, work_done); > - xenvif_napi_schedule_or_enable_events(queue); > + /* If the queue is rate-limited, it shall be > + * rescheduled in the timer callback. > + */ > + if (likely(!queue->rate_limited)) > + xenvif_napi_schedule_or_enable_events(queue); > } > > return work_done; > diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen- > netback/netback.c > index 602d408fa25e..5042ff8d449a 100644 > --- a/drivers/net/xen-netback/netback.c > +++ b/drivers/net/xen-netback/netback.c > @@ -180,6 +180,7 @@ static void tx_add_credit(struct xenvif_queue > *queue) > max_credit = ULONG_MAX; /* wrapped: clamp to > ULONG_MAX */ > > queue->remaining_credit = min(max_credit, max_burst); > + queue->rate_limited = false; > } > > void xenvif_tx_credit_callback(unsigned long data) > @@ -686,8 +687,10 @@ static bool tx_credit_exceeded(struct xenvif_queue > *queue, unsigned size) > msecs_to_jiffies(queue->credit_usec / 1000); > > /* Timer could already be pending in rare cases. */ > - if (timer_pending(&queue->credit_timeout)) > + if (timer_pending(&queue->credit_timeout)) { > + queue->rate_limited = true; > return true; > + } > > /* Passed the point where we can replenish credit? */ > if (time_after_eq64(now, next_credit)) { > @@ -702,6 +705,7 @@ static bool tx_credit_exceeded(struct xenvif_queue > *queue, unsigned size) > mod_timer(&queue->credit_timeout, > next_credit); > queue->credit_window_start = next_credit; > + queue->rate_limited = true; > > return true; > } > -- > 2.11.0
