[ovs-dev] [threaded-learning v2 12/25] guarded-list: New data structure for thread-safe queue.

Ben Pfaff blp at nicira.com
Thu Sep 12 07:39:24 UTC 2013


We already had queues that were suitable for replacement by this data
structure, and I intend to add another one later on.

flow_miss_batch_ofproto_destroyed() did not work well with the guarded-list
structure (it required either adding a lot more functions or breaking the
abstraction) so I changed the caller to just use udpif_revalidate().

Checking reval_seq at the end of handle_miss_upcalls() also didn't work
well with the abstraction, so I decided that since this was a corner case
anyway it would be acceptable to just drop those in flow_miss_batch_next().

Signed-off-by: Ben Pfaff <blp at nicira.com>
Acked-by: Ethan Jackson <ethan at nicira.com>
---
 lib/automake.mk               |    2 +
 lib/guarded-list.c            |   97 ++++++++++++++++++++
 lib/guarded-list.h            |   41 +++++++++
 ofproto/ofproto-dpif-upcall.c |  196 ++++++++++++-----------------------------
 ofproto/ofproto-dpif-upcall.h |    6 +-
 ofproto/ofproto-dpif.c        |   77 ++++------------
 6 files changed, 216 insertions(+), 203 deletions(-)
 create mode 100644 lib/guarded-list.c
 create mode 100644 lib/guarded-list.h

diff --git a/lib/automake.mk b/lib/automake.mk
index da1896a..92cfc13 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -58,6 +58,8 @@ lib_libopenvswitch_a_SOURCES = \
 	lib/fatal-signal.h \
 	lib/flow.c \
 	lib/flow.h \
+	lib/guarded-list.c \
+	lib/guarded-list.h \
 	lib/hash.c \
 	lib/hash.h \
 	lib/hindex.c \
diff --git a/lib/guarded-list.c b/lib/guarded-list.c
new file mode 100644
index 0000000..cbb2030
--- /dev/null
+++ b/lib/guarded-list.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2013 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "guarded-list.h"
+
+void
+guarded_list_init(struct guarded_list *list)
+{
+    ovs_mutex_init(&list->mutex);
+    list_init(&list->list);
+    list->n = 0;
+}
+
+void
+guarded_list_destroy(struct guarded_list *list)
+{
+    ovs_mutex_destroy(&list->mutex);
+}
+
+bool
+guarded_list_is_empty(const struct guarded_list *list)
+{
+    bool empty;
+
+    ovs_mutex_lock(&list->mutex);
+    empty = list->n == 0;
+    ovs_mutex_unlock(&list->mutex);
+
+    return empty;
+}
+
+/* If 'list' has fewer than 'max' elements, adds 'node' at the end of the list
+ * and returns the number of elements now on the list.
+ *
+ * If 'list' already has at least 'max' elements, returns 0 without modifying
+ * the list. */
+size_t
+guarded_list_push_back(struct guarded_list *list,
+                       struct list *node, size_t max)
+{
+    size_t retval = 0;
+
+    ovs_mutex_lock(&list->mutex);
+    if (list->n < max) {
+        list_push_back(&list->list, node);
+        retval = ++list->n;
+    }
+    ovs_mutex_unlock(&list->mutex);
+
+    return retval;
+}
+
+struct list *
+guarded_list_pop_front(struct guarded_list *list)
+{
+    struct list *node = NULL;
+
+    ovs_mutex_lock(&list->mutex);
+    if (list->n) {
+        node = list_pop_front(&list->list);
+        list->n--;
+    }
+    ovs_mutex_unlock(&list->mutex);
+
+    return node;
+}
+
+size_t
+guarded_list_pop_all(struct guarded_list *list, struct list *elements)
+{
+    size_t n;
+
+    ovs_mutex_lock(&list->mutex);
+    list_move(elements, &list->list);
+    n = list->n;
+
+    list_init(&list->list);
+    list->n = 0;
+    ovs_mutex_unlock(&list->mutex);
+
+    return n;
+}
diff --git a/lib/guarded-list.h b/lib/guarded-list.h
new file mode 100644
index 0000000..625865d
--- /dev/null
+++ b/lib/guarded-list.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2013 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef GUARDED_LIST_H
+#define GUARDED_LIST_H 1
+
+#include <stddef.h>
+#include "compiler.h"
+#include "list.h"
+#include "ovs-thread.h"
+
+struct guarded_list {
+    struct ovs_mutex mutex;
+    struct list list;
+    size_t n;
+};
+
+void guarded_list_init(struct guarded_list *);
+void guarded_list_destroy(struct guarded_list *);
+
+bool guarded_list_is_empty(const struct guarded_list *);
+
+size_t guarded_list_push_back(struct guarded_list *, struct list *,
+                              size_t max);
+struct list *guarded_list_pop_front(struct guarded_list *);
+size_t guarded_list_pop_all(struct guarded_list *, struct list *);
+
+#endif /* guarded-list.h */
diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
index ae856a4..850633d 100644
--- a/ofproto/ofproto-dpif-upcall.c
+++ b/ofproto/ofproto-dpif-upcall.c
@@ -23,6 +23,7 @@
 #include "dynamic-string.h"
 #include "dpif.h"
 #include "fail-open.h"
+#include "guarded-list.h"
 #include "latch.h"
 #include "seq.h"
 #include "list.h"
@@ -79,26 +80,15 @@ struct udpif {
     struct handler *handlers;          /* Miss handlers. */
     size_t n_handlers;
 
-    /* Atomic queue of unprocessed drop keys. */
-    struct ovs_mutex drop_key_mutex;
-    struct list drop_keys OVS_GUARDED;
-    size_t n_drop_keys OVS_GUARDED;
-
-    /* Atomic queue of special upcalls for ofproto-dpif to process. */
-    struct ovs_mutex upcall_mutex;
-    struct list upcalls OVS_GUARDED;
-    size_t n_upcalls OVS_GUARDED;
-
-    /* Atomic queue of flow_miss_batches. */
-    struct ovs_mutex fmb_mutex;
-    struct list fmbs OVS_GUARDED;
-    size_t n_fmbs OVS_GUARDED;
+    /* Queues to pass up to ofproto-dpif. */
+    struct guarded_list drop_keys; /* "struct drop key"s. */
+    struct guarded_list upcalls;   /* "struct upcall"s. */
+    struct guarded_list fmbs;      /* "struct flow_miss_batch"es. */
 
     /* Number of times udpif_revalidate() has been called. */
     atomic_uint reval_seq;
 
     struct seq *wait_seq;
-    uint64_t last_seq;
 
     struct latch exit_latch; /* Tells child threads to exit. */
 };
@@ -121,13 +111,10 @@ udpif_create(struct dpif_backer *backer, struct dpif *dpif)
     udpif->secret = random_uint32();
     udpif->wait_seq = seq_create();
     latch_init(&udpif->exit_latch);
-    list_init(&udpif->drop_keys);
-    list_init(&udpif->upcalls);
-    list_init(&udpif->fmbs);
+    guarded_list_init(&udpif->drop_keys);
+    guarded_list_init(&udpif->upcalls);
+    guarded_list_init(&udpif->fmbs);
     atomic_init(&udpif->reval_seq, 0);
-    ovs_mutex_init(&udpif->drop_key_mutex);
-    ovs_mutex_init(&udpif->upcall_mutex);
-    ovs_mutex_init(&udpif->fmb_mutex);
 
     return udpif;
 }
@@ -153,9 +140,9 @@ udpif_destroy(struct udpif *udpif)
         flow_miss_batch_destroy(fmb);
     }
 
-    ovs_mutex_destroy(&udpif->drop_key_mutex);
-    ovs_mutex_destroy(&udpif->upcall_mutex);
-    ovs_mutex_destroy(&udpif->fmb_mutex);
+    guarded_list_destroy(&udpif->drop_keys);
+    guarded_list_destroy(&udpif->upcalls);
+    guarded_list_destroy(&udpif->fmbs);
     latch_destroy(&udpif->exit_latch);
     seq_destroy(udpif->wait_seq);
     free(udpif);
@@ -229,33 +216,16 @@ udpif_recv_set(struct udpif *udpif, size_t n_handlers, bool enable)
 }
 
 void
-udpif_run(struct udpif *udpif)
-{
-    udpif->last_seq = seq_read(udpif->wait_seq);
-}
-
-void
 udpif_wait(struct udpif *udpif)
 {
-    ovs_mutex_lock(&udpif->drop_key_mutex);
-    if (udpif->n_drop_keys) {
-        poll_immediate_wake();
-    }
-    ovs_mutex_unlock(&udpif->drop_key_mutex);
-
-    ovs_mutex_lock(&udpif->upcall_mutex);
-    if (udpif->n_upcalls) {
-        poll_immediate_wake();
-    }
-    ovs_mutex_unlock(&udpif->upcall_mutex);
-
-    ovs_mutex_lock(&udpif->fmb_mutex);
-    if (udpif->n_fmbs) {
+    uint64_t seq = seq_read(udpif->wait_seq);
+    if (!guarded_list_is_empty(&udpif->drop_keys) ||
+        !guarded_list_is_empty(&udpif->upcalls) ||
+        !guarded_list_is_empty(&udpif->fmbs)) {
         poll_immediate_wake();
+    } else {
+        seq_wait(udpif->wait_seq, seq);
     }
-    ovs_mutex_unlock(&udpif->fmb_mutex);
-
-    seq_wait(udpif->wait_seq, udpif->last_seq);
 }
 
 /* Notifies 'udpif' that something changed which may render previous
@@ -265,20 +235,21 @@ udpif_revalidate(struct udpif *udpif)
 {
     struct flow_miss_batch *fmb, *next_fmb;
     unsigned int junk;
+    struct list fmbs;
 
     /* Since we remove each miss on revalidation, their statistics won't be
      * accounted to the appropriate 'facet's in the upper layer.  In most
      * cases, this is alright because we've already pushed the stats to the
      * relevant rules.  However, NetFlow requires absolute packet counts on
      * 'facet's which could now be incorrect. */
-    ovs_mutex_lock(&udpif->fmb_mutex);
     atomic_add(&udpif->reval_seq, 1, &junk);
-    LIST_FOR_EACH_SAFE (fmb, next_fmb, list_node, &udpif->fmbs) {
+
+    guarded_list_pop_all(&udpif->fmbs, &fmbs);
+    LIST_FOR_EACH_SAFE (fmb, next_fmb, list_node, &fmbs) {
         list_remove(&fmb->list_node);
         flow_miss_batch_destroy(fmb);
-        udpif->n_fmbs--;
     }
-    ovs_mutex_unlock(&udpif->fmb_mutex);
+
     udpif_drop_key_clear(udpif);
 }
 
@@ -288,16 +259,8 @@ udpif_revalidate(struct udpif *udpif)
 struct upcall *
 upcall_next(struct udpif *udpif)
 {
-    struct upcall *next = NULL;
-
-    ovs_mutex_lock(&udpif->upcall_mutex);
-    if (udpif->n_upcalls) {
-        udpif->n_upcalls--;
-        next = CONTAINER_OF(list_pop_front(&udpif->upcalls), struct upcall,
-                            list_node);
-    }
-    ovs_mutex_unlock(&udpif->upcall_mutex);
-    return next;
+    struct list *next = guarded_list_pop_front(&udpif->upcalls);
+    return next ? CONTAINER_OF(next, struct upcall, list_node) : NULL;
 }
 
 /* Destroys and deallocates 'upcall'. */
@@ -316,16 +279,24 @@ upcall_destroy(struct upcall *upcall)
 struct flow_miss_batch *
 flow_miss_batch_next(struct udpif *udpif)
 {
-    struct flow_miss_batch *next = NULL;
+    for (;;) {
+        struct flow_miss_batch *next;
+        unsigned int reval_seq;
+        struct list *next_node;
 
-    ovs_mutex_lock(&udpif->fmb_mutex);
-    if (udpif->n_fmbs) {
-        udpif->n_fmbs--;
-        next = CONTAINER_OF(list_pop_front(&udpif->fmbs),
-                            struct flow_miss_batch, list_node);
+        next_node = guarded_list_pop_front(&udpif->fmbs);
+        if (!next_node) {
+            return NULL;
+        }
+
+        next = CONTAINER_OF(next_node, struct flow_miss_batch, list_node);
+        atomic_read(&udpif->reval_seq, &reval_seq);
+        if (next->reval_seq == reval_seq) {
+            return next;
+        }
+
+        flow_miss_batch_destroy(next);
     }
-    ovs_mutex_unlock(&udpif->fmb_mutex);
-    return next;
 }
 
 /* Destroys and deallocates 'fmb'. */
@@ -347,52 +318,13 @@ flow_miss_batch_destroy(struct flow_miss_batch *fmb)
     free(fmb);
 }
 
-/* Discards any flow miss batches queued up in 'udpif' for 'ofproto' (because
- * 'ofproto' is being destroyed).
- *
- * 'ofproto''s xports must already have been removed, otherwise new flow miss
- * batches could still end up getting queued. */
-void
-flow_miss_batch_ofproto_destroyed(struct udpif *udpif,
-                                  const struct ofproto_dpif *ofproto)
-{
-    struct flow_miss_batch *fmb, *next_fmb;
-
-    ovs_mutex_lock(&udpif->fmb_mutex);
-    LIST_FOR_EACH_SAFE (fmb, next_fmb, list_node, &udpif->fmbs) {
-        struct flow_miss *miss, *next_miss;
-
-        HMAP_FOR_EACH_SAFE (miss, next_miss, hmap_node, &fmb->misses) {
-            if (miss->ofproto == ofproto) {
-                hmap_remove(&fmb->misses, &miss->hmap_node);
-                miss_destroy(miss);
-            }
-        }
-
-        if (hmap_is_empty(&fmb->misses)) {
-            list_remove(&fmb->list_node);
-            flow_miss_batch_destroy(fmb);
-            udpif->n_fmbs--;
-        }
-    }
-    ovs_mutex_unlock(&udpif->fmb_mutex);
-}
-
 /* Retreives the next drop key which ofproto-dpif needs to process.  The caller
  * is responsible for destroying it with drop_key_destroy(). */
 struct drop_key *
 drop_key_next(struct udpif *udpif)
 {
-    struct drop_key *next = NULL;
-
-    ovs_mutex_lock(&udpif->drop_key_mutex);
-    if (udpif->n_drop_keys) {
-        udpif->n_drop_keys--;
-        next = CONTAINER_OF(list_pop_front(&udpif->drop_keys), struct drop_key,
-                            list_node);
-    }
-    ovs_mutex_unlock(&udpif->drop_key_mutex);
-    return next;
+    struct list *next = guarded_list_pop_front(&udpif->drop_keys);
+    return next ? CONTAINER_OF(next, struct drop_key, list_node) : NULL;
 }
 
 /* Destorys and deallocates 'drop_key'. */
@@ -410,14 +342,13 @@ void
 udpif_drop_key_clear(struct udpif *udpif)
 {
     struct drop_key *drop_key, *next;
+    struct list list;
 
-    ovs_mutex_lock(&udpif->drop_key_mutex);
-    LIST_FOR_EACH_SAFE (drop_key, next, list_node, &udpif->drop_keys) {
+    guarded_list_pop_all(&udpif->drop_keys, &list);
+    LIST_FOR_EACH_SAFE (drop_key, next, list_node, &list) {
         list_remove(&drop_key->list_node);
         drop_key_destroy(drop_key);
-        udpif->n_drop_keys--;
     }
-    ovs_mutex_unlock(&udpif->drop_key_mutex);
 }
 
 /* The dispatcher thread is responsible for receving upcalls from the kernel,
@@ -618,17 +549,16 @@ recv_upcalls(struct udpif *udpif)
                 upcall_destroy(upcall);
             }
         } else {
-            ovs_mutex_lock(&udpif->upcall_mutex);
-            if (udpif->n_upcalls < MAX_QUEUE_LENGTH) {
-                n_udpif_new_upcalls = ++udpif->n_upcalls;
-                list_push_back(&udpif->upcalls, &upcall->list_node);
-                ovs_mutex_unlock(&udpif->upcall_mutex);
+            size_t len;
 
+            len = guarded_list_push_back(&udpif->upcalls, &upcall->list_node,
+                                         MAX_QUEUE_LENGTH);
+            if (len > 0) {
+                n_udpif_new_upcalls = len;
                 if (n_udpif_new_upcalls >= FLOW_MISS_MAX_BATCH) {
                     seq_change(udpif->wait_seq);
                 }
             } else {
-                ovs_mutex_unlock(&udpif->upcall_mutex);
                 COVERAGE_INC(upcall_queue_overflow);
                 upcall_destroy(upcall);
             }
@@ -762,20 +692,18 @@ handle_miss_upcalls(struct udpif *udpif, struct list *upcalls)
 {
     struct dpif_op *opsp[FLOW_MISS_MAX_BATCH];
     struct dpif_op ops[FLOW_MISS_MAX_BATCH];
-    unsigned int old_reval_seq, new_reval_seq;
     struct upcall *upcall, *next;
     struct flow_miss_batch *fmb;
     size_t n_upcalls, n_ops, i;
     struct flow_miss *miss;
 
-    atomic_read(&udpif->reval_seq, &old_reval_seq);
-
     /* Construct the to-do list.
      *
      * This just amounts to extracting the flow from each packet and sticking
      * the packets that have the same flow in the same "flow_miss" structure so
      * that we can process them together. */
     fmb = xmalloc(sizeof *fmb);
+    atomic_read(&udpif->reval_seq, &fmb->reval_seq);
     hmap_init(&fmb->misses);
     n_upcalls = 0;
     LIST_FOR_EACH_SAFE (upcall, next, list_node, upcalls) {
@@ -808,14 +736,10 @@ handle_miss_upcalls(struct udpif *udpif, struct list *upcalls)
             drop_key->key = xmemdup(dupcall->key, dupcall->key_len);
             drop_key->key_len = dupcall->key_len;
 
-            ovs_mutex_lock(&udpif->drop_key_mutex);
-            if (udpif->n_drop_keys < MAX_QUEUE_LENGTH) {
-                udpif->n_drop_keys++;
-                list_push_back(&udpif->drop_keys, &drop_key->list_node);
-                ovs_mutex_unlock(&udpif->drop_key_mutex);
+            if (guarded_list_push_back(&udpif->drop_keys, &drop_key->list_node,
+                                       MAX_QUEUE_LENGTH)) {
                 seq_change(udpif->wait_seq);
             } else {
-                ovs_mutex_unlock(&udpif->drop_key_mutex);
                 COVERAGE_INC(drop_queue_overflow);
                 drop_key_destroy(drop_key);
             }
@@ -868,21 +792,11 @@ handle_miss_upcalls(struct udpif *udpif, struct list *upcalls)
     }
     dpif_operate(udpif->dpif, opsp, n_ops);
 
-    ovs_mutex_lock(&udpif->fmb_mutex);
-    atomic_read(&udpif->reval_seq, &new_reval_seq);
-    if (old_reval_seq != new_reval_seq) {
-        /* udpif_revalidate() was called as we were calculating the actions.
-         * To be safe, we need to assume all the misses need revalidation. */
-        ovs_mutex_unlock(&udpif->fmb_mutex);
-        flow_miss_batch_destroy(fmb);
-    } else if (udpif->n_fmbs < MAX_QUEUE_LENGTH) {
-        udpif->n_fmbs++;
-        list_push_back(&udpif->fmbs, &fmb->list_node);
-        ovs_mutex_unlock(&udpif->fmb_mutex);
+    if (guarded_list_push_back(&udpif->fmbs, &fmb->list_node,
+                               MAX_QUEUE_LENGTH)) {
         seq_change(udpif->wait_seq);
     } else {
         COVERAGE_INC(fmb_queue_overflow);
-        ovs_mutex_unlock(&udpif->fmb_mutex);
         flow_miss_batch_destroy(fmb);
     }
 }
diff --git a/ofproto/ofproto-dpif-upcall.h b/ofproto/ofproto-dpif-upcall.h
index 8e8264e..57d462d 100644
--- a/ofproto/ofproto-dpif-upcall.h
+++ b/ofproto/ofproto-dpif-upcall.h
@@ -36,7 +36,6 @@ struct udpif *udpif_create(struct dpif_backer *, struct dpif *);
 void udpif_recv_set(struct udpif *, size_t n_workers, bool enable);
 void udpif_destroy(struct udpif *);
 
-void udpif_run(struct udpif *);
 void udpif_wait(struct udpif *);
 
 void udpif_revalidate(struct udpif *);
@@ -105,13 +104,12 @@ struct flow_miss_batch {
 
     struct flow_miss miss_buf[FLOW_MISS_MAX_BATCH];
     struct hmap misses;
+
+    unsigned int reval_seq;
 };
 
 struct flow_miss_batch *flow_miss_batch_next(struct udpif *);
 void flow_miss_batch_destroy(struct flow_miss_batch *);
-
-void flow_miss_batch_ofproto_destroyed(struct udpif *,
-                                       const struct ofproto_dpif *);
 
 /* Drop keys are odp flow keys which have drop flows installed in the kernel.
  * These are datapath flows which have no associated ofproto, if they did we
diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index 6f1a4e5..bf5af33 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -31,6 +31,7 @@
 #include "dpif.h"
 #include "dynamic-string.h"
 #include "fail-open.h"
+#include "guarded-list.h"
 #include "hmapx.h"
 #include "lacp.h"
 #include "learn.h"
@@ -507,13 +508,8 @@ struct ofproto_dpif {
     uint64_t n_missed;
 
     /* Work queues. */
-    struct ovs_mutex flow_mod_mutex;
-    struct list flow_mods OVS_GUARDED;
-    size_t n_flow_mods OVS_GUARDED;
-
-    struct ovs_mutex pin_mutex;
-    struct list pins OVS_GUARDED;
-    size_t n_pins OVS_GUARDED;
+    struct guarded_list flow_mods; /* Contains "struct flow_mod"s. */
+    struct guarded_list pins;      /* Contains "struct ofputil_packet_in"s. */
 };
 
 /* By default, flows in the datapath are wildcarded (megaflows).  They
@@ -560,18 +556,11 @@ void
 ofproto_dpif_flow_mod(struct ofproto_dpif *ofproto,
                       struct ofputil_flow_mod *fm)
 {
-    ovs_mutex_lock(&ofproto->flow_mod_mutex);
-    if (ofproto->n_flow_mods > 1024) {
-        ovs_mutex_unlock(&ofproto->flow_mod_mutex);
+    if (!guarded_list_push_back(&ofproto->flow_mods, &fm->list_node, 1024)) {
         COVERAGE_INC(flow_mod_overflow);
         free(fm->ofpacts);
         free(fm);
-        return;
     }
-
-    list_push_back(&ofproto->flow_mods, &fm->list_node);
-    ofproto->n_flow_mods++;
-    ovs_mutex_unlock(&ofproto->flow_mod_mutex);
 }
 
 /* Appends 'pin' to the queue of "packet ins" to be sent to the controller.
@@ -580,18 +569,11 @@ void
 ofproto_dpif_send_packet_in(struct ofproto_dpif *ofproto,
                             struct ofputil_packet_in *pin)
 {
-    ovs_mutex_lock(&ofproto->pin_mutex);
-    if (ofproto->n_pins > 1024) {
-        ovs_mutex_unlock(&ofproto->pin_mutex);
+    if (!guarded_list_push_back(&ofproto->pins, &pin->list_node, 1024)) {
         COVERAGE_INC(packet_in_overflow);
         free(CONST_CAST(void *, pin->packet));
         free(pin);
-        return;
     }
-
-    list_push_back(&ofproto->pins, &pin->list_node);
-    ofproto->n_pins++;
-    ovs_mutex_unlock(&ofproto->pin_mutex);
 }
 
 /* Factory functions. */
@@ -1024,7 +1006,6 @@ process_dpif_port_error(struct dpif_backer *backer, int error)
 static int
 dpif_backer_run_fast(struct dpif_backer *backer)
 {
-    udpif_run(backer->udpif);
     handle_upcalls(backer);
 
     return 0;
@@ -1286,17 +1267,8 @@ construct(struct ofproto *ofproto_)
     classifier_init(&ofproto->facets);
     ofproto->consistency_rl = LLONG_MIN;
 
-    ovs_mutex_init(&ofproto->flow_mod_mutex);
-    ovs_mutex_lock(&ofproto->flow_mod_mutex);
-    list_init(&ofproto->flow_mods);
-    ofproto->n_flow_mods = 0;
-    ovs_mutex_unlock(&ofproto->flow_mod_mutex);
-
-    ovs_mutex_init(&ofproto->pin_mutex);
-    ovs_mutex_lock(&ofproto->pin_mutex);
-    list_init(&ofproto->pins);
-    ofproto->n_pins = 0;
-    ovs_mutex_unlock(&ofproto->pin_mutex);
+    guarded_list_init(&ofproto->flow_mods);
+    guarded_list_init(&ofproto->pins);
 
     ofproto_dpif_unixctl_init();
 
@@ -1422,6 +1394,7 @@ destruct(struct ofproto *ofproto_)
     struct ofputil_packet_in *pin, *next_pin;
     struct ofputil_flow_mod *fm, *next_fm;
     struct facet *facet, *next_facet;
+    struct list flow_mods, pins;
     struct cls_cursor cursor;
     struct oftable *table;
 
@@ -1437,7 +1410,9 @@ destruct(struct ofproto *ofproto_)
     xlate_remove_ofproto(ofproto);
     ovs_rwlock_unlock(&xlate_rwlock);
 
-    flow_miss_batch_ofproto_destroyed(ofproto->backer->udpif, ofproto);
+    /* Discard any flow_miss_batches queued up for 'ofproto', avoiding a
+     * use-after-free error. */
+    udpif_revalidate(ofproto->backer->udpif);
 
     hmap_remove(&all_ofproto_dpifs, &ofproto->all_ofproto_dpifs_node);
 
@@ -1452,25 +1427,21 @@ destruct(struct ofproto *ofproto_)
         ovs_rwlock_unlock(&table->cls.rwlock);
     }
 
-    ovs_mutex_lock(&ofproto->flow_mod_mutex);
-    LIST_FOR_EACH_SAFE (fm, next_fm, list_node, &ofproto->flow_mods) {
+    guarded_list_pop_all(&ofproto->flow_mods, &flow_mods);
+    LIST_FOR_EACH_SAFE (fm, next_fm, list_node, &flow_mods) {
         list_remove(&fm->list_node);
-        ofproto->n_flow_mods--;
         free(fm->ofpacts);
         free(fm);
     }
-    ovs_mutex_unlock(&ofproto->flow_mod_mutex);
-    ovs_mutex_destroy(&ofproto->flow_mod_mutex);
+    guarded_list_destroy(&ofproto->flow_mods);
 
-    ovs_mutex_lock(&ofproto->pin_mutex);
-    LIST_FOR_EACH_SAFE (pin, next_pin, list_node, &ofproto->pins) {
+    guarded_list_pop_all(&ofproto->pins, &pins);
+    LIST_FOR_EACH_SAFE (pin, next_pin, list_node, &pins) {
         list_remove(&pin->list_node);
-        ofproto->n_pins--;
         free(CONST_CAST(void *, pin->packet));
         free(pin);
     }
-    ovs_mutex_unlock(&ofproto->pin_mutex);
-    ovs_mutex_destroy(&ofproto->pin_mutex);
+    guarded_list_destroy(&ofproto->pins);
 
     mbridge_unref(ofproto->mbridge);
 
@@ -1508,12 +1479,7 @@ run_fast(struct ofproto *ofproto_)
         return 0;
     }
 
-    ovs_mutex_lock(&ofproto->flow_mod_mutex);
-    list_move(&flow_mods, &ofproto->flow_mods);
-    list_init(&ofproto->flow_mods);
-    ofproto->n_flow_mods = 0;
-    ovs_mutex_unlock(&ofproto->flow_mod_mutex);
-
+    guarded_list_pop_all(&ofproto->flow_mods, &flow_mods);
     LIST_FOR_EACH_SAFE (fm, next_fm, list_node, &flow_mods) {
         int error = ofproto_flow_mod(&ofproto->up, fm);
         if (error && !VLOG_DROP_WARN(&rl)) {
@@ -1526,12 +1492,7 @@ run_fast(struct ofproto *ofproto_)
         free(fm);
     }
 
-    ovs_mutex_lock(&ofproto->pin_mutex);
-    list_move(&pins, &ofproto->pins);
-    list_init(&ofproto->pins);
-    ofproto->n_pins = 0;
-    ovs_mutex_unlock(&ofproto->pin_mutex);
-
+    guarded_list_pop_all(&ofproto->pins, &pins);
     LIST_FOR_EACH_SAFE (pin, next_pin, list_node, &pins) {
         connmgr_send_packet_in(ofproto->up.connmgr, pin);
         list_remove(&pin->list_node);
-- 
1.7.10.4




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