[ovs-dev] [PATCH v7] dpif-netlink: distribute polling to discreet handlers

Mark Gray mark.d.gray at redhat.com
Tue Sep 8 17:27:48 UTC 2020


From: Aaron Conole <aconole at redhat.com>

Currently, the channel handlers are polled globally.  On some
systems, this causes a thundering herd issue where multiple
handler threads become active, only to do no work and immediately
sleep.

The approach here is to push the netlink socket channels to discreet
handler threads to process, rather than polling on every thread.
This will eliminate the need to wake multiple threads.

To check:

  ip netns add left
  ip netns add right
  ip link add center-left type veth peer name left0 netns left
  ip link add center-right type veth peer name right0 netns right
  ip link set center-left up
  ip link set center-right up
  ip -n left ip link set left0 up
  ip -n left ip addr add 172.31.110.10/24 dev left0
  ip -n right ip link set right0 up
  ip -n right ip addr add 172.31.110.11/24 dev right0

  ovs-vsctl add-br br0
  ovs-vsctl add-port br0 center-right
  ovs-vsctl add-port br0 center-left

  # in one terminal
  perf record -e sched:sched_wakeup,irq:softirq_entry -ag

  # in a separate terminal
  ip netns exec left arping -I left0 -c 1 172.31.110.11

  # in the perf terminal after exiting
  perf script

Look for the number of 'handler' threads which were made active.

Suggested-by: Ben Pfaff <blp at ovn.org>
Co-authored-by: Mark Gray <mark.d.gray at redhat.com>
Reported-by: David Ahern <dsahern at gmail.com>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-dev/2019-December/365857.html
Cc: Matteo Croce <technoboy85 at gmail.com>
Cc: Flavio Leitner <fbl at sysclose.org>
Fixes: 69c51582f ("dpif-netlink: don't allocate per thread netlink sockets")
Signed-off-by: Aaron Conole <aconole at redhat.com>
Signed-off-by: Mark Gray <mark.d.gray at redhat.com>
---


v2: Oops - forgot to commit my whitespace cleanups.
v3: one port latency results as per Matteo's comments

    Stock:
      min/avg/max/mdev = 21.5/36.5/96.5/1.0 us
    With Patch:
      min/avg/max/mdev = 5.3/9.7/98.4/0.5 us 
v4: Oops - first email did not send
v5:   min/avg/max/mdev = 9.3/10.4/33.6/2.2 us
v6: Split out the AUTHORS patch and added a cover letter as
    per Ilya's suggestion.
    Fixed 0-day issues.
v7: Merged patches as per Flavio's suggestion. This is
    no longer a series. Fixed some other small issues.

 lib/dpif-netlink.c | 325 +++++++++++++++++++++++++--------------------
 lib/id-pool.c      |  10 ++
 lib/id-pool.h      |   1 +
 3 files changed, 195 insertions(+), 141 deletions(-)

diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index 7da4fb54d..4ecf0c51c 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -37,6 +37,7 @@
 #include "dpif-provider.h"
 #include "fat-rwlock.h"
 #include "flow.h"
+#include "id-pool.h"
 #include "netdev-linux.h"
 #include "netdev-offload.h"
 #include "netdev-provider.h"
@@ -160,6 +161,9 @@ static void dpif_netlink_flow_to_dpif_flow(struct dpif_flow *,
 
 /* One of the dpif channels between the kernel and userspace. */
 struct dpif_channel {
+    struct hmap_node hmap_node;
+    struct dpif_handler *handler;
+    uint32_t port_idx;
     struct nl_sock *sock;       /* Netlink socket. */
     long long int last_poll;    /* Last time this channel was polled. */
 };
@@ -183,6 +187,8 @@ struct dpif_handler {
     int n_events;                 /* Num events returned by epoll_wait(). */
     int event_offset;             /* Offset into 'epoll_events'. */
 
+    struct hmap channels;         /* map of channels for each port. */
+
 #ifdef _WIN32
     /* Pool of sockets. */
     struct dpif_windows_vport_sock *vport_sock_pool;
@@ -201,9 +207,8 @@ struct dpif_netlink {
     struct fat_rwlock upcall_lock;
     struct dpif_handler *handlers;
     uint32_t n_handlers;           /* Num of upcall handlers. */
-    struct dpif_channel *channels; /* Array of channels for each port. */
-    int uc_array_size;             /* Size of 'handler->channels' and */
-                                   /* 'handler->epoll_events'. */
+
+    struct id_pool *port_ids;      /* Set of added port ids */
 
     /* Change notification. */
     struct nl_sock *port_notifier; /* vport multicast group subscriber. */
@@ -287,6 +292,44 @@ close_nl_sock(struct nl_sock *sock)
 #endif
 }
 
+static size_t
+dpif_handler_channels_count(const struct dpif_handler *handler)
+{
+    return hmap_count(&handler->channels);
+}
+
+static struct dpif_channel *
+dpif_handler_channel_find(struct dpif_handler *handler, uint32_t idx)
+{
+    struct dpif_channel *channel;
+
+    HMAP_FOR_EACH_WITH_HASH (channel, hmap_node, hash_int(idx, 0),
+                             &handler->channels) {
+        if (channel->port_idx == idx) {
+            return channel;
+        }
+    }
+
+    return NULL;
+}
+
+static void
+dpif_channel_del(struct dpif_netlink *dpif,
+                 struct dpif_channel *channel)
+{
+    struct dpif_handler *handler = channel->handler;
+
+#ifndef _WIN32
+    epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
+              nl_sock_fd(channel->sock), NULL);
+    nl_sock_destroy(channel->sock);
+#endif
+    hmap_remove(&handler->channels, &channel->hmap_node);
+    id_pool_free_id(dpif->port_ids, channel->port_idx);
+    handler->event_offset = handler->n_events = 0;
+    free(channel);
+}
+
 static struct dpif_netlink *
 dpif_netlink_cast(const struct dpif *dpif)
 {
@@ -385,6 +428,7 @@ open_dpif(const struct dpif_netlink_dp *dp, struct dpif **dpifp)
 
     dpif->dp_ifindex = dp->dp_ifindex;
     dpif->user_features = dp->user_features;
+    dpif->port_ids = id_pool_create(0, MAX_PORTS);
     *dpifp = &dpif->dpif;
 
     return 0;
@@ -452,161 +496,145 @@ static bool
 vport_get_pid(struct dpif_netlink *dpif, uint32_t port_idx,
               uint32_t *upcall_pid)
 {
-    /* Since the nl_sock can only be assigned in either all
-     * or none "dpif" channels, the following check
-     * would suffice. */
-    if (!dpif->channels[port_idx].sock) {
+    size_t i;
+
+    ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
+
+    if (!id_pool_has_id(dpif->port_ids, port_idx)) {
         return false;
     }
-    ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
 
-    *upcall_pid = nl_sock_pid(dpif->channels[port_idx].sock);
+    /* The 'port_idx' should only be valid for a single handler. */
+    for (i = 0; i < dpif->n_handlers; i++) {
+        struct dpif_channel *channel;
+
+        channel = dpif_handler_channel_find(&dpif->handlers[i], port_idx);
+        if (channel) {
+            *upcall_pid = nl_sock_pid(channel->sock);
+            return true;
+        }
+    }
 
-    return true;
+    return false;
 }
 
 static int
 vport_add_channel(struct dpif_netlink *dpif, odp_port_t port_no,
                   struct nl_sock *sock)
 {
-    struct epoll_event event;
     uint32_t port_idx = odp_to_u32(port_no);
+    struct dpif_channel *channel;
+    struct dpif_handler *handler;
+    struct epoll_event event;
     size_t i;
-    int error;
 
-    if (dpif->handlers == NULL) {
+    if (dpif->handlers == NULL ||
+        id_pool_has_id(dpif->port_ids, port_idx)) {
         close_nl_sock(sock);
-        return 0;
+        return EINVAL;
     }
 
-    /* We assume that the datapath densely chooses port numbers, which can
-     * therefore be used as an index into 'channels' and 'epoll_events' of
-     * 'dpif'. */
-    if (port_idx >= dpif->uc_array_size) {
-        uint32_t new_size = port_idx + 1;
-
-        if (new_size > MAX_PORTS) {
-            VLOG_WARN_RL(&error_rl, "%s: datapath port %"PRIu32" too big",
-                         dpif_name(&dpif->dpif), port_no);
-            return EFBIG;
-        }
+    if (port_idx >= MAX_PORTS) {
+        VLOG_WARN_RL(&error_rl, "%s: datapath port %"PRIu32" too big",
+                     dpif_name(&dpif->dpif), port_no);
+        return EFBIG;
+    }
 
-        dpif->channels = xrealloc(dpif->channels,
-                                  new_size * sizeof *dpif->channels);
+    handler = &dpif->handlers[0];
 
-        for (i = dpif->uc_array_size; i < new_size; i++) {
-            dpif->channels[i].sock = NULL;
+    for (i = 0; i < dpif->n_handlers; i++) {
+        if (dpif_handler_channels_count(&dpif->handlers[i]) <
+            dpif_handler_channels_count(handler)) {
+            handler = &dpif->handlers[i];
         }
+    }
 
-        for (i = 0; i < dpif->n_handlers; i++) {
-            struct dpif_handler *handler = &dpif->handlers[i];
+    channel = xmalloc(sizeof *channel);
+    channel->port_idx = port_idx;
+    channel->sock = sock;
+    channel->last_poll = LLONG_MIN;
+    channel->handler = handler;
+    hmap_insert(&handler->channels, &channel->hmap_node,
+                hash_int(port_idx, 0));
 
-            handler->epoll_events = xrealloc(handler->epoll_events,
-                new_size * sizeof *handler->epoll_events);
-
-        }
-        dpif->uc_array_size = new_size;
-    }
+    handler->epoll_events = xrealloc(handler->epoll_events,
+                                     dpif_handler_channels_count(handler) *
+                                     sizeof *handler->epoll_events);
 
     memset(&event, 0, sizeof event);
     event.events = EPOLLIN | EPOLLEXCLUSIVE;
     event.data.u32 = port_idx;
 
-    for (i = 0; i < dpif->n_handlers; i++) {
-        struct dpif_handler *handler = &dpif->handlers[i];
-
 #ifndef _WIN32
-        if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(sock),
-                      &event) < 0) {
-            error = errno;
-            goto error;
-        }
-#endif
-    }
-    dpif->channels[port_idx].sock = sock;
-    dpif->channels[port_idx].last_poll = LLONG_MIN;
-
-    return 0;
-
-error:
-#ifndef _WIN32
-    while (i--) {
-        epoll_ctl(dpif->handlers[i].epoll_fd, EPOLL_CTL_DEL,
-                  nl_sock_fd(sock), NULL);
+    if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(sock),
+                  &event) < 0) {
+        hmap_remove(&handler->channels, &channel->hmap_node);
+        free(channel);
+        id_pool_free_id(dpif->port_ids, port_idx);
+        return errno;
     }
 #endif
-    dpif->channels[port_idx].sock = NULL;
 
-    return error;
+    id_pool_add(dpif->port_ids, port_idx);
+    return 0;
 }
 
-static void
-vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no)
+static bool
+vport_del_channel(struct dpif_netlink *dpif, odp_port_t port_no)
 {
-    uint32_t port_idx = odp_to_u32(port_no);
+    struct dpif_channel *channel = NULL;
+    bool found_channel = false;
     size_t i;
 
-    if (!dpif->handlers || port_idx >= dpif->uc_array_size
-        || !dpif->channels[port_idx].sock) {
-        return;
-    }
-
     for (i = 0; i < dpif->n_handlers; i++) {
-        struct dpif_handler *handler = &dpif->handlers[i];
-#ifndef _WIN32
-        epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
-                  nl_sock_fd(dpif->channels[port_idx].sock), NULL);
-#endif
-        handler->event_offset = handler->n_events = 0;
+        channel = dpif_handler_channel_find(&dpif->handlers[i],
+                                            odp_to_u32(port_no));
+        if (channel) {
+            dpif_channel_del(dpif, channel);
+            found_channel = true;
+            break;
+        }
     }
-#ifndef _WIN32
-    nl_sock_destroy(dpif->channels[port_idx].sock);
-#endif
-    dpif->channels[port_idx].sock = NULL;
+
+    return found_channel;
 }
 
 static void
 destroy_all_channels(struct dpif_netlink *dpif)
     OVS_REQ_WRLOCK(dpif->upcall_lock)
 {
-    unsigned int i;
+    size_t i;
 
     if (!dpif->handlers) {
         return;
     }
 
-    for (i = 0; i < dpif->uc_array_size; i++ ) {
-        struct dpif_netlink_vport vport_request;
-        uint32_t upcall_pids = 0;
-
-        if (!dpif->channels[i].sock) {
-            continue;
-        }
-
-        /* Turn off upcalls. */
-        dpif_netlink_vport_init(&vport_request);
-        vport_request.cmd = OVS_VPORT_CMD_SET;
-        vport_request.dp_ifindex = dpif->dp_ifindex;
-        vport_request.port_no = u32_to_odp(i);
-        vport_request.n_upcall_pids = 1;
-        vport_request.upcall_pids = &upcall_pids;
-        dpif_netlink_vport_transact(&vport_request, NULL, NULL);
-
-        vport_del_channels(dpif, u32_to_odp(i));
-    }
-
     for (i = 0; i < dpif->n_handlers; i++) {
         struct dpif_handler *handler = &dpif->handlers[i];
+        struct dpif_channel *channel, *next;
+
+        HMAP_FOR_EACH_SAFE (channel, next, hmap_node, &handler->channels) {
+            struct dpif_netlink_vport vport_request;
+            uint32_t upcall_pids = 0;
+            /* Turn off upcalls. */
+            dpif_netlink_vport_init(&vport_request);
+            vport_request.cmd = OVS_VPORT_CMD_SET;
+            vport_request.dp_ifindex = dpif->dp_ifindex;
+            vport_request.port_no = u32_to_odp(channel->port_idx);
+            vport_request.n_upcall_pids = 1;
+            vport_request.upcall_pids = &upcall_pids;
+            dpif_netlink_vport_transact(&vport_request, NULL, NULL);
+            ovs_assert(channel != NULL);
+            dpif_channel_del(dpif, channel);
+        }
 
         dpif_netlink_handler_uninit(handler);
         free(handler->epoll_events);
     }
-    free(dpif->channels);
+
     free(dpif->handlers);
     dpif->handlers = NULL;
-    dpif->channels = NULL;
     dpif->n_handlers = 0;
-    dpif->uc_array_size = 0;
 }
 
 static void
@@ -618,9 +646,11 @@ dpif_netlink_close(struct dpif *dpif_)
 
     fat_rwlock_wrlock(&dpif->upcall_lock);
     destroy_all_channels(dpif);
+    id_pool_destroy(dpif->port_ids);
     fat_rwlock_unlock(&dpif->upcall_lock);
 
     fat_rwlock_destroy(&dpif->upcall_lock);
+
     free(dpif);
 }
 
@@ -1003,7 +1033,9 @@ dpif_netlink_port_del__(struct dpif_netlink *dpif, odp_port_t port_no)
 #endif
     error = dpif_netlink_vport_transact(&vport, NULL, NULL);
 
-    vport_del_channels(dpif, port_no);
+    if (!vport_del_channel(dpif, port_no)) {
+        return EINVAL;
+    }
 
     if (!error && !ovs_tunnels_out_of_tree) {
         error = dpif_netlink_rtnl_port_destroy(dpif_port.name, dpif_port.type);
@@ -1084,23 +1116,39 @@ dpif_netlink_port_get_pid__(const struct dpif_netlink *dpif,
                             odp_port_t port_no)
     OVS_REQ_RDLOCK(dpif->upcall_lock)
 {
+    struct dpif_channel *min_channel = NULL, *found_channel = NULL;
     uint32_t port_idx = odp_to_u32(port_no);
     uint32_t pid = 0;
+    size_t i;
+
+    /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s
+     * channel, since it is not heavily loaded. */
+    uint32_t idx = port_no == ODPP_NONE ? 0 : port_idx;
+
+    if (!id_pool_has_id(dpif->port_ids, port_idx)) {
+        return 0;
+    }
 
-    if (dpif->handlers && dpif->uc_array_size > 0) {
-        /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s
-         * channel, since it is not heavily loaded. */
-        uint32_t idx = port_idx >= dpif->uc_array_size ? 0 : port_idx;
-
-        /* Needs to check in case the socket pointer is changed in between
-         * the holding of upcall_lock.  A known case happens when the main
-         * thread deletes the vport while the handler thread is handling
-         * the upcall from that port. */
-        if (dpif->channels[idx].sock) {
-            pid = nl_sock_pid(dpif->channels[idx].sock);
+    if (dpif->handlers) {
+        for (i = 0; i < dpif->n_handlers; i++) {
+            if (dpif_handler_channel_find(&dpif->handlers[i], idx)) {
+                found_channel = dpif_handler_channel_find(&dpif->handlers[i],
+                                                          idx);
+                break;
+            }
+
+            if (dpif_handler_channel_find(&dpif->handlers[i], 0)) {
+                min_channel = dpif_handler_channel_find(&dpif->handlers[i], 0);
+            }
         }
     }
 
+    if (found_channel) {
+        pid = nl_sock_pid(found_channel->sock);
+    } else if (min_channel) {
+        pid = nl_sock_pid(min_channel->sock);
+    }
+
     return pid;
 }
 
@@ -2342,12 +2390,14 @@ dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops,
 static void
 dpif_netlink_handler_uninit(struct dpif_handler *handler)
 {
+    hmap_destroy(&handler->channels);
     vport_delete_sock_pool(handler);
 }
 
 static int
 dpif_netlink_handler_init(struct dpif_handler *handler)
 {
+    hmap_init(&handler->channels);
     return vport_create_sock_pool(handler);
 }
 #else
@@ -2355,6 +2405,7 @@ dpif_netlink_handler_init(struct dpif_handler *handler)
 static int
 dpif_netlink_handler_init(struct dpif_handler *handler)
 {
+    hmap_init(&handler->channels);
     handler->epoll_fd = epoll_create(10);
     return handler->epoll_fd < 0 ? errno : 0;
 }
@@ -2362,6 +2413,7 @@ dpif_netlink_handler_init(struct dpif_handler *handler)
 static void
 dpif_netlink_handler_uninit(struct dpif_handler *handler)
 {
+    hmap_destroy(&handler->channels);
     close(handler->epoll_fd);
 }
 #endif
@@ -2374,9 +2426,7 @@ static int
 dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
     OVS_REQ_WRLOCK(dpif->upcall_lock)
 {
-    unsigned long int *keep_channels;
     struct dpif_netlink_vport vport;
-    size_t keep_channels_nbits;
     struct nl_dump dump;
     uint64_t reply_stub[NL_DUMP_BUFSIZE / 8];
     struct ofpbuf buf;
@@ -2412,13 +2462,9 @@ dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
 
     for (i = 0; i < n_handlers; i++) {
         struct dpif_handler *handler = &dpif->handlers[i];
-
         handler->event_offset = handler->n_events = 0;
     }
 
-    keep_channels_nbits = dpif->uc_array_size;
-    keep_channels = bitmap_allocate(keep_channels_nbits);
-
     ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub);
     dpif_netlink_port_dump_start__(dpif, &dump);
     while (!dpif_netlink_port_dump_next__(dpif, &dump, &vport, &buf)) {
@@ -2426,8 +2472,7 @@ dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
         uint32_t upcall_pid;
         int error;
 
-        if (port_no >= dpif->uc_array_size
-            || !vport_get_pid(dpif, port_no, &upcall_pid)) {
+        if (!vport_get_pid(dpif, port_no, &upcall_pid)) {
             struct nl_sock *sock;
             error = create_nl_sock(dpif, &sock);
 
@@ -2475,25 +2520,15 @@ dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
             }
         }
 
-        if (port_no < keep_channels_nbits) {
-            bitmap_set1(keep_channels, port_no);
-        }
         continue;
 
     error:
-        vport_del_channels(dpif, vport.port_no);
+        vport_del_channel(dpif, port_no);
     }
+
     nl_dump_done(&dump);
     ofpbuf_uninit(&buf);
 
-    /* Discard any saved channels that we didn't reuse. */
-    for (i = 0; i < keep_channels_nbits; i++) {
-        if (!bitmap_is_set(keep_channels, i)) {
-            vport_del_channels(dpif, u32_to_odp(i));
-        }
-    }
-    free(keep_channels);
-
     return retval;
 }
 
@@ -2714,6 +2749,8 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, uint32_t handler_id,
     OVS_REQ_RDLOCK(dpif->upcall_lock)
 {
     struct dpif_handler *handler;
+    size_t n_channels;
+
     int read_tries = 0;
 
     if (!dpif->handlers || handler_id >= dpif->n_handlers) {
@@ -2721,14 +2758,15 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, uint32_t handler_id,
     }
 
     handler = &dpif->handlers[handler_id];
-    if (handler->event_offset >= handler->n_events) {
+    n_channels = dpif_handler_channels_count(handler);
+    if (handler->event_offset >= handler->n_events && n_channels) {
         int retval;
 
         handler->event_offset = handler->n_events = 0;
 
         do {
             retval = epoll_wait(handler->epoll_fd, handler->epoll_events,
-                                dpif->uc_array_size, 0);
+                                n_channels, 0);
         } while (retval < 0 && errno == EINTR);
 
         if (retval < 0) {
@@ -2741,7 +2779,10 @@ dpif_netlink_recv__(struct dpif_netlink *dpif, uint32_t handler_id,
 
     while (handler->event_offset < handler->n_events) {
         int idx = handler->epoll_events[handler->event_offset].data.u32;
-        struct dpif_channel *ch = &dpif->channels[idx];
+        struct dpif_channel *ch = dpif_handler_channel_find(handler, idx);
+        if (!ch) {
+            return EAGAIN;
+        }
 
         handler->event_offset++;
 
@@ -2845,12 +2886,14 @@ dpif_netlink_recv_purge__(struct dpif_netlink *dpif)
     if (dpif->handlers) {
         size_t i;
 
-        if (!dpif->channels[0].sock) {
-            return;
-        }
-        for (i = 0; i < dpif->uc_array_size; i++ ) {
+        for (i = 0; i < dpif->n_handlers; i++) {
+            struct dpif_handler *handler = &dpif->handlers[i];
+            struct dpif_channel *channel;
+
+            HMAP_FOR_EACH (channel, hmap_node, &handler->channels) {
+                nl_sock_drain(channel->sock);
+            }
 
-            nl_sock_drain(dpif->channels[i].sock);
         }
     }
 }
diff --git a/lib/id-pool.c b/lib/id-pool.c
index 69910ad08..bef822f6b 100644
--- a/lib/id-pool.c
+++ b/lib/id-pool.c
@@ -93,6 +93,16 @@ id_pool_find(struct id_pool *pool, uint32_t id)
     return NULL;
 }
 
+bool
+id_pool_has_id(struct id_pool *pool, uint32_t id)
+{
+    if (!id_pool_find(pool, id)) {
+        return false;
+    }
+
+    return true;
+}
+
 void
 id_pool_add(struct id_pool *pool, uint32_t id)
 {
diff --git a/lib/id-pool.h b/lib/id-pool.h
index 8721f8793..62876e2a5 100644
--- a/lib/id-pool.h
+++ b/lib/id-pool.h
@@ -29,6 +29,7 @@ void id_pool_destroy(struct id_pool *);
 bool id_pool_alloc_id(struct id_pool *, uint32_t *id);
 void id_pool_free_id(struct id_pool *, uint32_t id);
 void id_pool_add(struct id_pool *, uint32_t id);
+bool id_pool_has_id(struct id_pool *, uint32_t id);
 
 /*
  * ID pool.
-- 
2.26.2



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