X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Flibsystemd-rtnl%2Fsd-rtnl.c;h=08b82ab2a94f3f6dca6bb5e21934d90cbb48cfcc;hp=8ea11df808d2981dda7c59cedd141e3ed542b035;hb=eca7a27add5aa3ec85c272fc4cef287fdca034ce;hpb=a33dece5f8cce7f1946263bec76068ef84abc07b

diff --git a/src/libsystemd-rtnl/sd-rtnl.c b/src/libsystemd-rtnl/sd-rtnl.c
index 8ea11df80..08b82ab2a 100644
--- a/src/libsystemd-rtnl/sd-rtnl.c
+++ b/src/libsystemd-rtnl/sd-rtnl.c
@@ -24,6 +24,7 @@
 
 #include "macro.h"
 #include "util.h"
+#include "hashmap.h"
 
 #include "sd-rtnl.h"
 #include "rtnl-internal.h"
@@ -46,6 +47,16 @@ static int sd_rtnl_new(sd_rtnl **ret) {
 
         rtnl->original_pid = getpid();
 
+        LIST_HEAD_INIT(rtnl->match_callbacks);
+
+        /* We guarantee that wqueue always has space for at least
+         * one entry */
+        rtnl->wqueue = new(sd_rtnl_message*, 1);
+        if (!rtnl->wqueue) {
+                free(rtnl);
+                return -ENOMEM;
+        }
+
         *ret = rtnl;
         return 0;
 }
@@ -64,6 +75,8 @@ int sd_rtnl_open(uint32_t groups, sd_rtnl **ret) {
         socklen_t addrlen;
         int r;
 
+        assert_return(ret, -EINVAL);
+
         r = sd_rtnl_new(&rtnl);
         if (r < 0)
                 return r;
@@ -98,23 +111,40 @@ sd_rtnl *sd_rtnl_ref(sd_rtnl *rtnl) {
 }
 
 sd_rtnl *sd_rtnl_unref(sd_rtnl *rtnl) {
+
         if (rtnl && REFCNT_DEC(rtnl->n_ref) <= 0) {
+                struct match_callback *f;
+                unsigned i;
+
+                for (i = 0; i < rtnl->rqueue_size; i++)
+                        sd_rtnl_message_unref(rtnl->rqueue[i]);
+                free(rtnl->rqueue);
+
+                for (i = 0; i < rtnl->wqueue_size; i++)
+                        sd_rtnl_message_unref(rtnl->wqueue[i]);
+                free(rtnl->wqueue);
+
+                hashmap_free_free(rtnl->reply_callbacks);
+                prioq_free(rtnl->reply_callbacks_prioq);
+
+                while ((f = rtnl->match_callbacks)) {
+                        LIST_REMOVE(match_callbacks, rtnl->match_callbacks, f);
+                        free(f);
+                }
+
                 if (rtnl->fd >= 0)
                         close_nointr_nofail(rtnl->fd);
+
                 free(rtnl);
         }
 
         return NULL;
 }
 
-int sd_rtnl_send_with_reply_and_block(sd_rtnl *nl,
-                sd_rtnl_message *message,
-                uint64_t usec,
-                sd_rtnl_message **ret) {
-        struct pollfd p[1] = {};
-        struct timespec left;
-        usec_t timeout;
-        int r, serial;
+int sd_rtnl_send(sd_rtnl *nl,
+                 sd_rtnl_message *message,
+                 uint32_t *serial) {
+        int r;
 
         assert_return(nl, -EINVAL);
         assert_return(!rtnl_pid_changed(nl), -ECHILD);
@@ -124,82 +154,717 @@ int sd_rtnl_send_with_reply_and_block(sd_rtnl *nl,
         if (r < 0)
                 return r;
 
-        serial = message_get_serial(message);
+        if (nl->wqueue_size <= 0) {
+                /* send directly */
+                r = socket_write_message(nl, message);
+                if (r < 0)
+                        return r;
+                else if (r == 0) {
+                        /* nothing was sent, so let's put it on
+                         * the queue */
+                        nl->wqueue[0] = sd_rtnl_message_ref(message);
+                        nl->wqueue_size = 1;
+                }
+        } else {
+                sd_rtnl_message **q;
 
-        p[0].fd = nl->fd;
-        p[0].events = POLLOUT;
+                /* append to queue */
+                if (nl->wqueue_size >= RTNL_WQUEUE_MAX)
+                        return -ENOBUFS;
 
-        if (usec == (uint64_t) -1)
-                timeout = 0;
-        else if (usec == 0)
-                timeout = now(CLOCK_MONOTONIC) + RTNL_DEFAULT_TIMEOUT;
-        else
-                timeout = now(CLOCK_MONOTONIC) + usec;
+                q = realloc(nl->wqueue, sizeof(sd_rtnl_message*) * (nl->wqueue_size + 1));
+                if (!q)
+                        return -ENOMEM;
 
-        for (;;) {
-                if (timeout) {
-                        usec_t n;
+                nl->wqueue = q;
+                q[nl->wqueue_size ++] = sd_rtnl_message_ref(message);
+        }
 
-                        n = now(CLOCK_MONOTONIC);
-                        if (n >= timeout)
-                                return -ETIMEDOUT;
+        if (serial)
+                *serial = message_get_serial(message);
 
-                        timespec_store(&left, timeout - n);
-                }
+        return 1;
+}
 
-                r = ppoll(p, 1, timeout ? &left : NULL, NULL);
-                if (r < 0)
-                        return 0;
+static int dispatch_rqueue(sd_rtnl *rtnl, sd_rtnl_message **message) {
+        sd_rtnl_message *z = NULL;
+        int r;
 
-                r = socket_write_message(nl, message);
+        assert(rtnl);
+        assert(message);
+
+        if (rtnl->rqueue_size > 0) {
+                /* Dispatch a queued message */
+
+                *message = rtnl->rqueue[0];
+                rtnl->rqueue_size --;
+                memmove(rtnl->rqueue, rtnl->rqueue + 1, sizeof(sd_rtnl_message*) * rtnl->rqueue_size);
+
+                return 1;
+        }
+
+        /* Try to read a new message */
+        r = socket_read_message(rtnl, &z);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return 0;
+
+        *message = z;
+
+        return 1;
+}
+
+static int dispatch_wqueue(sd_rtnl *rtnl) {
+        int r, ret = 0;
+
+        assert(rtnl);
+
+        while (rtnl->wqueue_size > 0) {
+                r = socket_write_message(rtnl, rtnl->wqueue[0]);
                 if (r < 0)
                         return r;
-
-                if (r > 0) {
-                        break;
+                else if (r == 0)
+                        /* Didn't do anything this time */
+                        return ret;
+                else {
+                        /* see equivalent in sd-bus.c */
+                        sd_rtnl_message_unref(rtnl->wqueue[0]);
+                        rtnl->wqueue_size --;
+                        memmove(rtnl->wqueue, rtnl->wqueue + 1, sizeof(sd_rtnl_message*) * rtnl->wqueue_size);
+
+                        ret = 1;
                 }
         }
 
-        p[0].events = POLLIN;
+        return ret;
+}
 
-        for (;;) {
-                _cleanup_sd_rtnl_message_unref_ sd_rtnl_message *reply = NULL;
+static int process_timeout(sd_rtnl *rtnl) {
+        _cleanup_sd_rtnl_message_unref_ sd_rtnl_message *m = NULL;
+        struct reply_callback *c;
+        usec_t n;
+        int r;
 
-                if (timeout) {
-                        usec_t n;
+        assert(rtnl);
 
-                        n = now(CLOCK_MONOTONIC);
-                        if (n >= timeout)
-                                return -ETIMEDOUT;
+        c = prioq_peek(rtnl->reply_callbacks_prioq);
+        if (!c)
+                return 0;
+
+        n = now(CLOCK_MONOTONIC);
+        if (c->timeout > n)
+                return 0;
 
-                        timespec_store(&left, timeout - n);
+        r = message_new_synthetic_error(-ETIMEDOUT, c->serial, &m);
+        if (r < 0)
+                return r;
+
+        assert_se(prioq_pop(rtnl->reply_callbacks_prioq) == c);
+        hashmap_remove(rtnl->reply_callbacks, &c->serial);
+
+        r = c->callback(rtnl, m, c->userdata);
+        free(c);
+
+        return r < 0 ? r : 1;
+}
+
+static int process_reply(sd_rtnl *rtnl, sd_rtnl_message *m) {
+        struct reply_callback *c;
+        uint64_t serial;
+        int r;
+
+        assert(rtnl);
+        assert(m);
+
+        serial = message_get_serial(m);
+        c = hashmap_remove(rtnl->reply_callbacks, &serial);
+        if (!c)
+                return 0;
+
+        if (c->timeout != 0)
+                prioq_remove(rtnl->reply_callbacks_prioq, c, &c->prioq_idx);
+
+        r = c->callback(rtnl, m, c->userdata);
+        free(c);
+
+        return r;
+}
+
+static int process_match(sd_rtnl *rtnl, sd_rtnl_message *m) {
+        struct match_callback *c;
+        uint16_t type;
+        int r;
+
+        assert(rtnl);
+        assert(m);
+
+        r = sd_rtnl_message_get_type(m, &type);
+        if (r < 0)
+                return r;
+
+        LIST_FOREACH(match_callbacks, c, rtnl->match_callbacks) {
+                if (type == c->type) {
+                        r = c->callback(rtnl, m, c->userdata);
+                        if (r != 0)
+                                return r;
                 }
+        }
+
+        return 0;
+}
+
+static int process_running(sd_rtnl *rtnl, sd_rtnl_message **ret) {
+        _cleanup_sd_rtnl_message_unref_ sd_rtnl_message *m = NULL;
+        int r;
+
+        assert(rtnl);
+
+        r = process_timeout(rtnl);
+        if (r != 0)
+                goto null_message;
+
+        r = dispatch_wqueue(rtnl);
+        if (r != 0)
+                goto null_message;
+
+        r = dispatch_rqueue(rtnl, &m);
+        if (r < 0)
+                return r;
+        if (!m)
+                goto null_message;
+
+        r = process_reply(rtnl, m);
+        if (r != 0)
+                goto null_message;
+
+        r = process_match(rtnl, m);
+        if (r != 0)
+                goto null_message;
+
+        if (ret) {
+                *ret = m;
+                m = NULL;
+
+                return 1;
+        }
+
+        return 1;
 
-                r = ppoll(p, 1, timeout ? &left : NULL, NULL);
+null_message:
+        if (r >= 0 && ret)
+                *ret = NULL;
+
+        return r;
+}
+
+int sd_rtnl_process(sd_rtnl *rtnl, sd_rtnl_message **ret) {
+        RTNL_DONT_DESTROY(rtnl);
+        int r;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+        assert_return(!rtnl->processing, -EBUSY);
+
+        rtnl->processing = true;
+        r = process_running(rtnl, ret);
+        rtnl->processing = false;
+
+        return r;
+}
+
+static usec_t calc_elapse(uint64_t usec) {
+        if (usec == (uint64_t) -1)
+                return 0;
+
+        if (usec == 0)
+                usec = RTNL_DEFAULT_TIMEOUT;
+
+        return now(CLOCK_MONOTONIC) + usec;
+}
+
+static int rtnl_poll(sd_rtnl *rtnl, bool need_more, uint64_t timeout_usec) {
+        struct pollfd p[1] = {};
+        struct timespec ts;
+        usec_t m = (usec_t) -1;
+        int r, e;
+
+        assert(rtnl);
+
+        e = sd_rtnl_get_events(rtnl);
+        if (e < 0)
+                return e;
+
+        if (need_more)
+                /* Caller wants more data, and doesn't care about
+                 * what's been read or any other timeouts. */
+                return e |= POLLIN;
+        else {
+                usec_t until;
+                /* Caller wants to process if there is something to
+                 * process, but doesn't care otherwise */
+
+                r = sd_rtnl_get_timeout(rtnl, &until);
                 if (r < 0)
                         return r;
+                if (r > 0) {
+                        usec_t nw;
+                        nw = now(CLOCK_MONOTONIC);
+                        m = until > nw ? until - nw : 0;
+                }
+        }
+
+        if (timeout_usec != (uint64_t) -1 && (m == (uint64_t) -1 || timeout_usec < m))
+                m = timeout_usec;
+
+        p[0].fd = rtnl->fd;
+        p[0].events = e;
+
+        r = ppoll(p, 1, m == (uint64_t) -1 ? NULL : timespec_store(&ts, m), NULL);
+        if (r < 0)
+                return -errno;
+
+        return r > 0 ? 1 : 0;
+}
+
+int sd_rtnl_wait(sd_rtnl *nl, uint64_t timeout_usec) {
+        assert_return(nl, -EINVAL);
+        assert_return(!rtnl_pid_changed(nl), -ECHILD);
+
+        if (nl->rqueue_size > 0)
+                return 0;
+
+        return rtnl_poll(nl, false, timeout_usec);
+}
+
+static int timeout_compare(const void *a, const void *b) {
+        const struct reply_callback *x = a, *y = b;
+
+        if (x->timeout != 0 && y->timeout == 0)
+                return -1;
+
+        if (x->timeout == 0 && y->timeout != 0)
+                return 1;
+
+        if (x->timeout < y->timeout)
+                return -1;
+
+        if (x->timeout > y->timeout)
+                return 1;
+
+        return 0;
+}
+
+int sd_rtnl_call_async(sd_rtnl *nl,
+                       sd_rtnl_message *m,
+                       sd_rtnl_message_handler_t callback,
+                       void *userdata,
+                       uint64_t usec,
+                       uint32_t *serial) {
+        struct reply_callback *c;
+        uint32_t s;
+        int r, k;
+
+        assert_return(nl, -EINVAL);
+        assert_return(m, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(!rtnl_pid_changed(nl), -ECHILD);
 
-                r = socket_read_message(nl, &reply);
+        r = hashmap_ensure_allocated(&nl->reply_callbacks, uint64_hash_func, uint64_compare_func);
+        if (r < 0)
+                return r;
+
+        if (usec != (uint64_t) -1) {
+                r = prioq_ensure_allocated(&nl->reply_callbacks_prioq, timeout_compare);
                 if (r < 0)
                         return r;
+        }
 
+        c = new0(struct reply_callback, 1);
+        if (!c)
+                return -ENOMEM;
+
+        c->callback = callback;
+        c->userdata = userdata;
+        c->timeout = calc_elapse(usec);
+
+        k = sd_rtnl_send(nl, m, &s);
+        if (k < 0) {
+                free(c);
+                return k;
+        }
+
+        c->serial = s;
+
+        r = hashmap_put(nl->reply_callbacks, &c->serial, c);
+        if (r < 0) {
+                free(c);
+                return r;
+        }
+
+        if (c->timeout != 0) {
+                r = prioq_put(nl->reply_callbacks_prioq, c, &c->prioq_idx);
                 if (r > 0) {
-                        int received_serial = message_get_serial(reply);
+                        c->timeout = 0;
+                        sd_rtnl_call_async_cancel(nl, c->serial);
+                        return r;
+                }
+        }
+
+        if (serial)
+                *serial = s;
+
+        return k;
+}
+
+int sd_rtnl_call_async_cancel(sd_rtnl *nl, uint32_t serial) {
+        struct reply_callback *c;
+        uint64_t s = serial;
+
+        assert_return(nl, -EINVAL);
+        assert_return(serial != 0, -EINVAL);
+        assert_return(!rtnl_pid_changed(nl), -ECHILD);
+
+        c = hashmap_remove(nl->reply_callbacks, &s);
+        if (!c)
+                return 0;
+
+        if (c->timeout != 0)
+                prioq_remove(nl->reply_callbacks_prioq, c, &c->prioq_idx);
+
+        free(c);
+        return 1;
+}
+
+int sd_rtnl_call(sd_rtnl *nl,
+                sd_rtnl_message *message,
+                uint64_t usec,
+                sd_rtnl_message **ret) {
+        usec_t timeout;
+        uint32_t serial;
+        bool room = false;
+        int r;
+
+        assert_return(nl, -EINVAL);
+        assert_return(!rtnl_pid_changed(nl), -ECHILD);
+        assert_return(message, -EINVAL);
+
+        r = sd_rtnl_send(nl, message, &serial);
+        if (r < 0)
+                return r;
+
+        timeout = calc_elapse(usec);
+
+        for (;;) {
+                usec_t left;
+                _cleanup_sd_rtnl_message_unref_ sd_rtnl_message *incoming = NULL;
+
+                if (!room) {
+                        sd_rtnl_message **q;
+
+                        if (nl->rqueue_size >= RTNL_RQUEUE_MAX)
+                                return -ENOBUFS;
+
+                        /* Make sure there's room for queueing this
+                         * locally, before we read the message */
+
+                        q = realloc(nl->rqueue, (nl->rqueue_size + 1) * sizeof(sd_rtnl_message*));
+                        if (!q)
+                                return -ENOMEM;
+
+                        nl->rqueue = q;
+                        room = true;
+                }
+
+                r = socket_read_message(nl, &incoming);
+                if (r < 0)
+                        return r;
+                if (incoming) {
+                        uint32_t received_serial = message_get_serial(incoming);
 
                         if (received_serial == serial) {
-                                r = message_get_errno(reply);
+                                r = sd_rtnl_message_get_errno(incoming);
                                 if (r < 0)
                                         return r;
 
                                 if (ret) {
-                                        *ret = reply;
-                                        reply = NULL;
+                                        *ret = incoming;
+                                        incoming = NULL;
                                 }
 
-                                break;;
+                                return 1;
                         }
+
+                        /* Room was allocated on the queue above */
+                        nl->rqueue[nl->rqueue_size ++] = incoming;
+                        incoming = NULL;
+                        room = false;
+
+                        /* Try to read more, right away */
+                        continue;
                 }
+                if (r != 0)
+                        continue;
+
+                if (timeout > 0) {
+                        usec_t n;
+
+                        n = now(CLOCK_MONOTONIC);
+                        if (n >= timeout)
+                                return -ETIMEDOUT;
+
+                        left = timeout - n;
+                } else
+                        left = (uint64_t) -1;
+
+                r = rtnl_poll(nl, true, left);
+                if (r < 0)
+                        return r;
+
+                r = dispatch_wqueue(nl);
+                if (r < 0)
+                        return r;
+        }
+}
+
+int sd_rtnl_flush(sd_rtnl *rtnl) {
+        int r;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+
+        if (rtnl->wqueue_size <= 0)
+                return 0;
+
+        for (;;) {
+                r = dispatch_wqueue(rtnl);
+                if (r < 0)
+                        return r;
+
+                if (rtnl->wqueue_size <= 0)
+                        return 0;
+
+                r = rtnl_poll(rtnl, false, (uint64_t) -1);
+                if (r < 0)
+                        return r;
+        }
+}
+
+int sd_rtnl_get_events(sd_rtnl *rtnl) {
+        int flags = 0;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+
+        if (rtnl->rqueue_size <= 0)
+                flags |= POLLIN;
+        if (rtnl->wqueue_size > 0)
+                flags |= POLLOUT;
+
+        return flags;
+}
+
+int sd_rtnl_get_timeout(sd_rtnl *rtnl, uint64_t *timeout_usec) {
+        struct reply_callback *c;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(timeout_usec, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+
+        if (rtnl->rqueue_size > 0) {
+                *timeout_usec = 0;
+                return 1;
+        }
+
+        c = prioq_peek(rtnl->reply_callbacks_prioq);
+        if (!c) {
+                *timeout_usec = (uint64_t) -1;
+                return 0;
+        }
+
+        *timeout_usec = c->timeout;
+
+        return 1;
+}
+
+static int io_callback(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        sd_rtnl *rtnl = userdata;
+        int r;
+
+        assert(rtnl);
+
+        r = sd_rtnl_process(rtnl, NULL);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int time_callback(sd_event_source *s, uint64_t usec, void *userdata) {
+        sd_rtnl *rtnl = userdata;
+        int r;
+
+        assert(rtnl);
+
+        r = sd_rtnl_process(rtnl, NULL);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int prepare_callback(sd_event_source *s, void *userdata) {
+        sd_rtnl *rtnl = userdata;
+        int r, e;
+        usec_t until;
+
+        assert(s);
+        assert(rtnl);
+
+        e = sd_rtnl_get_events(rtnl);
+        if (e < 0)
+                return e;
+
+        r = sd_event_source_set_io_events(rtnl->io_event_source, e);
+        if (r < 0)
+                return r;
+
+        r = sd_rtnl_get_timeout(rtnl, &until);
+        if (r < 0)
+                return r;
+        if (r > 0) {
+                int j;
+
+                j = sd_event_source_set_time(rtnl->time_event_source, until);
+                if (j < 0)
+                        return j;
+        }
+
+        r = sd_event_source_set_enabled(rtnl->time_event_source, r > 0);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int exit_callback(sd_event_source *event, void *userdata) {
+        sd_rtnl *rtnl = userdata;
+
+        assert(event);
+
+        sd_rtnl_flush(rtnl);
+
+        return 1;
+}
+
+int sd_rtnl_attach_event(sd_rtnl *rtnl, sd_event *event, int priority) {
+        int r;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(!rtnl->event, -EBUSY);
+
+        assert(!rtnl->io_event_source);
+        assert(!rtnl->time_event_source);
+
+        if (event)
+                rtnl->event = sd_event_ref(event);
+        else {
+                r = sd_event_default(&rtnl->event);
+                if (r < 0)
+                        return r;
         }
 
+        r = sd_event_add_io(rtnl->event, rtnl->fd, 0, io_callback, rtnl, &rtnl->io_event_source);
+        if (r < 0)
+                goto fail;
+
+        r = sd_event_source_set_priority(rtnl->io_event_source, priority);
+        if (r < 0)
+                goto fail;
+
+        r = sd_event_source_set_prepare(rtnl->io_event_source, prepare_callback);
+        if (r < 0)
+                goto fail;
+
+        r = sd_event_add_monotonic(rtnl->event, 0, 0, time_callback, rtnl, &rtnl->time_event_source);
+        if (r < 0)
+                goto fail;
+
+        r = sd_event_source_set_priority(rtnl->time_event_source, priority);
+        if (r < 0)
+                goto fail;
+
+        r = sd_event_add_exit(rtnl->event, exit_callback, rtnl, &rtnl->exit_event_source);
+        if (r < 0)
+                goto fail;
+
+        return 0;
+
+fail:
+        sd_rtnl_detach_event(rtnl);
+        return r;
+}
+
+int sd_rtnl_detach_event(sd_rtnl *rtnl) {
+        assert_return(rtnl, -EINVAL);
+        assert_return(rtnl->event, -ENXIO);
+
+        if (rtnl->io_event_source)
+                rtnl->io_event_source = sd_event_source_unref(rtnl->io_event_source);
+
+        if (rtnl->time_event_source)
+                rtnl->time_event_source = sd_event_source_unref(rtnl->time_event_source);
+
+        if (rtnl->exit_event_source)
+                rtnl->exit_event_source = sd_event_source_unref(rtnl->exit_event_source);
+
+        if (rtnl->event)
+                rtnl->event = sd_event_unref(rtnl->event);
+
+        return 0;
+}
+
+int sd_rtnl_add_match(sd_rtnl *rtnl,
+                      uint16_t type,
+                      sd_rtnl_message_handler_t callback,
+                      void *userdata) {
+        struct match_callback *c;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+        assert_return(message_type_is_link(type) || message_type_is_addr(type) || message_type_is_route(type), -ENOTSUP);
+
+        c = new0(struct match_callback, 1);
+        if (!c)
+                return -ENOMEM;
+
+        c->callback = callback;
+        c->type = type;
+        c->userdata = userdata;
+
+        LIST_PREPEND(match_callbacks, rtnl->match_callbacks, c);
+
+        return 0;
+}
+
+int sd_rtnl_remove_match(sd_rtnl *rtnl,
+                         uint16_t type,
+                         sd_rtnl_message_handler_t callback,
+                         void *userdata) {
+        struct match_callback *c;
+
+        assert_return(rtnl, -EINVAL);
+        assert_return(callback, -EINVAL);
+        assert_return(!rtnl_pid_changed(rtnl), -ECHILD);
+
+        LIST_FOREACH(match_callbacks, c, rtnl->match_callbacks)
+                if (c->callback == callback && c->type == type && c->userdata == userdata) {
+                        LIST_REMOVE(match_callbacks, rtnl->match_callbacks, c);
+                        free(c);
+
+                        return 1;
+                }
+
         return 0;
 }