From: Wei Liu Date: Wed, 21 Jun 2017 09:21:22 +0000 (+0100) Subject: xen-netback: correctly schedule rate-limited queues X-Git-Tag: v4.1.12-111.0.20170918_2215~213 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=5639f6e6dafc0a38cb7d89d8aa621bd94ee6c335;p=users%2Fjedix%2Flinux-maple.git 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 Signed-off-by: Wei Liu Tested-by: Jean-Louis Dupond Reviewed-by: Paul Durrant Signed-off-by: David S. Miller OraBug: 26662731 (cherry picked from commit dfa523ae9f2542bee4cddaea37b3be3e157f6e6b) Signed-off-by: Boris Ostrovsky Reviewed-by: Joao Martins Conflicts: drivers/net/xen-netback/interface.c (Upstream's code used napi_complete_done()) --- diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h index 2c2f98fa575ba..7c4d2e133411f 100644 --- a/drivers/net/xen-netback/common.h +++ b/drivers/net/xen-netback/common.h @@ -223,6 +223,7 @@ struct xenvif_queue { /* Per-queue data for xenvif */ unsigned long remaining_credit; struct timer_list credit_timeout; u64 credit_window_start; + bool rate_limited; /* Permanent grant mappings */ struct xenvif_grant_mapping grant; diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 77db33fea67c1..461b764f0567c 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -108,7 +108,11 @@ static int xenvif_poll(struct napi_struct *napi, int budget) if (work_done < budget) { napi_complete(napi); - 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 d988c2d15af41..faf9272290c4d 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -194,6 +194,7 @@ 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) @@ -788,8 +789,10 @@ 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)) { @@ -804,6 +807,7 @@ 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; }