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xen-netback: correctly schedule rate-limited queues

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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 <jean-louis@dupond.be>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Tested-by: Jean-Louis Dupond <jean-louis@dupond.be>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Liu 2017-06-21 10:21:22 +01:00 committed by David S. Miller
parent 191cdb3822
commit dfa523ae9f
3 changed files with 11 additions and 2 deletions
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1
drivers/net/xen-netback/common.h
View File

@ -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;

4
drivers/net/xen-netback/interface.c
View File

@ -106,6 +106,10 @@ static int xenvif_poll(struct napi_struct *napi, int budget)
if (work_done < budget) {
napi_complete_done(napi, work_done);
/* 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);
}

6
drivers/net/xen-netback/netback.c
View File

@ -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;
}