[PATCH iproute2-next 5/7] devlink: Set NETLINK_NO_ENOBUFS when monitoring events

[Ido Schimmel]

From: Ido Schimmel <ido...@mellanox.com>

If we lost an event, there is nothing we can do in order to recover it.
Set above mentioned socket option on the netlink socket when monitoring
devlink events, so that `devlink monitor` will not abort in case we are
not draining the receive buffer fast enough.

The number of events we lost can be retrieved using:

# cat /proc/net/netlink | grep `pidof devlink` | awk '{ print $9 }'

Signed-off-by: Ido Schimmel <ido...@mellanox.com>
Acked-by: Jiri Pirko <j...@mellanox.com>
---
 devlink/devlink.c | 22 +++++++++++++++++++++-
 devlink/mnlg.c    | 12 ++++++++++++
 devlink/mnlg.h    |  2 ++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/devlink/devlink.c b/devlink/devlink.c
index b9fce850ee00..817b74259ec3 100644
--- a/devlink/devlink.c
+++ b/devlink/devlink.c
@@ -140,6 +140,19 @@ static int _mnlg_socket_group_add(struct mnlg_socket *nlg,
        return 0;
 }
 
+static int _mnlg_socket_setsockopt(struct mnlg_socket *nlg, int type,
+                                  void *buf, socklen_t len)
+{
+       int err;
+
+       err = mnlg_socket_setsockopt(nlg, type, buf, len);
+       if (err < 0) {
+               pr_err("Failed to call mnlg_socket_setsockopt\n");
+               return -errno;
+       }
+       return 0;
+}
+
 struct ifname_map {
        struct list_head list;
        char *bus_name;
@@ -4020,7 +4033,7 @@ static int cmd_mon_show_cb(const struct nlmsghdr *nlh, 
void *data)
 
 static int cmd_mon_show(struct dl *dl)
 {
-       int err;
+       int err, one = 1;
        unsigned int index = 0;
        const char *cur_obj;
 
@@ -4035,6 +4048,13 @@ static int cmd_mon_show(struct dl *dl)
                        return -EINVAL;
                }
        }
+       /* It is possible to lose some events if we are not draining the socket
+        * receive buffer fast enough. Keep processing events and do not abort.
+        */
+       err = _mnlg_socket_setsockopt(dl->nlg, NETLINK_NO_ENOBUFS, &one,
+                                     sizeof(one));
+       if (err)
+               return err;
        err = _mnlg_socket_group_add(dl->nlg, DEVLINK_GENL_MCGRP_CONFIG_NAME);
        if (err)
                return err;
diff --git a/devlink/mnlg.c b/devlink/mnlg.c
index ee125df042f0..23e6e794b508 100644
--- a/devlink/mnlg.c
+++ b/devlink/mnlg.c
@@ -231,6 +231,18 @@ int mnlg_socket_group_add(struct mnlg_socket *nlg, const 
char *group_name)
        return 0;
 }
 
+int mnlg_socket_setsockopt(struct mnlg_socket *nlg, int type, void *buf,
+                          socklen_t len)
+{
+       int err;
+
+       err = mnl_socket_setsockopt(nlg->nl, type, buf, len);
+       if (err < 0)
+               return err;
+
+       return 0;
+}
+
 static int get_family_id_attr_cb(const struct nlattr *attr, void *data)
 {
        const struct nlattr **tb = data;
diff --git a/devlink/mnlg.h b/devlink/mnlg.h
index 4d1babf3b4c2..49154215729e 100644
--- a/devlink/mnlg.h
+++ b/devlink/mnlg.h
@@ -21,6 +21,8 @@ struct nlmsghdr *mnlg_msg_prepare(struct mnlg_socket *nlg, 
uint8_t cmd,
 int mnlg_socket_send(struct mnlg_socket *nlg, const struct nlmsghdr *nlh);
 int mnlg_socket_recv_run(struct mnlg_socket *nlg, mnl_cb_t data_cb, void 
*data);
 int mnlg_socket_group_add(struct mnlg_socket *nlg, const char *group_name);
+int mnlg_socket_setsockopt(struct mnlg_socket *nlg, int type, void *buf,
+                          socklen_t len);
 struct mnlg_socket *mnlg_socket_open(const char *family_name, uint8_t version);
 void mnlg_socket_close(struct mnlg_socket *nlg);
 
-- 
2.20.1