[Xen-devel] [PATCH 1/4] net: Move napi polling code out of net_rx_action

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

This patch creates a new function napi_poll and moves the napi
polling code from net_rx_action into it.

Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
---

 net/core/dev.c |   98 +++++++++++++++++++++++++++++++--------------------------
 1 file changed, 54 insertions(+), 44 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index f411c28..f7c4f4e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4557,6 +4557,59 @@ void netif_napi_del(struct napi_struct *napi)
 }
 EXPORT_SYMBOL(netif_napi_del);
 
+static int napi_poll(struct napi_struct *n, struct list_head *repoll)
+{
+       void *have;
+       int work, weight;
+
+       list_del_init(&n->poll_list);
+
+       have = netpoll_poll_lock(n);
+
+       weight = n->weight;
+
+       /* This NAPI_STATE_SCHED test is for avoiding a race
+        * with netpoll's poll_napi().  Only the entity which
+        * obtains the lock and sees NAPI_STATE_SCHED set will
+        * actually make the ->poll() call.  Therefore we avoid
+        * accidentally calling ->poll() when NAPI is not scheduled.
+        */
+       work = 0;
+       if (test_bit(NAPI_STATE_SCHED, &n->state)) {
+               work = n->poll(n, weight);
+               trace_napi_poll(n);
+       }
+
+       WARN_ON_ONCE(work > weight);
+
+       if (likely(work < weight))
+               goto out_unlock;
+
+       /* Drivers must not modify the NAPI state if they
+        * consume the entire weight.  In such cases this code
+        * still "owns" the NAPI instance and therefore can
+        * move the instance around on the list at-will.
+        */
+       if (unlikely(napi_disable_pending(n))) {
+               napi_complete(n);
+               goto out_unlock;
+       }
+
+       if (n->gro_list) {
+               /* flush too old packets
+                * If HZ < 1000, flush all packets.
+                */
+               napi_gro_flush(n, HZ >= 1000);
+       }
+
+       list_add_tail(&n->poll_list, repoll);
+
+out_unlock:
+       netpoll_poll_unlock(have);
+
+       return work;
+}
+
 static void net_rx_action(struct softirq_action *h)
 {
        struct softnet_data *sd = this_cpu_ptr(&softnet_data);
@@ -4564,7 +4617,6 @@ static void net_rx_action(struct softirq_action *h)
        int budget = netdev_budget;
        LIST_HEAD(list);
        LIST_HEAD(repoll);
-       void *have;
 
        local_irq_disable();
        list_splice_init(&sd->poll_list, &list);
@@ -4572,7 +4624,6 @@ static void net_rx_action(struct softirq_action *h)
 
        while (!list_empty(&list)) {
                struct napi_struct *n;
-               int work, weight;
 
                /* If softirq window is exhausted then punt.
                 * Allow this to run for 2 jiffies since which will allow
@@ -4583,48 +4634,7 @@ static void net_rx_action(struct softirq_action *h)
 
 
                n = list_first_entry(&list, struct napi_struct, poll_list);
-               list_del_init(&n->poll_list);
-
-               have = netpoll_poll_lock(n);
-
-               weight = n->weight;
-
-               /* This NAPI_STATE_SCHED test is for avoiding a race
-                * with netpoll's poll_napi().  Only the entity which
-                * obtains the lock and sees NAPI_STATE_SCHED set will
-                * actually make the ->poll() call.  Therefore we avoid
-                * accidentally calling ->poll() when NAPI is not scheduled.
-                */
-               work = 0;
-               if (test_bit(NAPI_STATE_SCHED, &n->state)) {
-                       work = n->poll(n, weight);
-                       trace_napi_poll(n);
-               }
-
-               WARN_ON_ONCE(work > weight);
-
-               budget -= work;
-
-               /* Drivers must not modify the NAPI state if they
-                * consume the entire weight.  In such cases this code
-                * still "owns" the NAPI instance and therefore can
-                * move the instance around on the list at-will.
-                */
-               if (unlikely(work == weight)) {
-                       if (unlikely(napi_disable_pending(n))) {
-                               napi_complete(n);
-                       } else {
-                               if (n->gro_list) {
-                                       /* flush too old packets
-                                        * If HZ < 1000, flush all packets.
-                                        */
-                                       napi_gro_flush(n, HZ >= 1000);
-                               }
-                               list_add_tail(&n->poll_list, &repoll);
-                       }
-               }
-
-               netpoll_poll_unlock(have);
+               budget -= napi_poll(n, &repoll);
        }
 
        if (!sd_has_rps_ipi_waiting(sd) &&

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