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platform: workaround NLE_MSG_TRUNC failure of nl_recv() with too small buffer size

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We don't want to enable MSG_PEEK due to the overhead. But when we detect
that we just lost a message due to MSG_TRUNC, increase the buffer size and
retry.

See-also: 55ea6e6b6c
(cherry picked from commit 9fafb382db)
This commit is contained in:
Thomas Haller 2016-11-30 16:40:54 +01:00
parent c7a873e1a9
commit 5dbd54552d
1 changed files with 34 additions and 1 deletions
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35
src/platform/nm-linux-platform.c
View file

@ -57,6 +57,7 @@
/* nm-internal error codes for libnl. Make sure they don't overlap. */
#define _NLE_NM_NOBUFS 500
#define _NLE_MSG_TRUNC 501
/*********************************************************************************************/
@ -5969,6 +5970,23 @@ continue_reading:
n = -NLE_AGAIN;
}
break;
case -NLE_MSG_TRUNC: {
int buf_size;
/* the message receive buffer was too small. We lost one message, which
* is unfortunate. Try to double the buffer size for the next time. */
buf_size = nl_socket_get_msg_buf_size (sk);
if (buf_size < 512*1024) {
buf_size *= 2;
_LOGT ("netlink: recvmsg: increase message buffer size for recvmsg() to %d bytes", buf_size);
if (nl_socket_set_msg_buf_size (sk, buf_size) < 0)
nm_assert_not_reached ();
if (!handle_events)
goto continue_reading;
}
n = -_NLE_MSG_TRUNC;
break;
}
case -NLE_NOMEM:
if (errno == ENOBUFS) {
/* we are very much interested in a overrun of the receive buffer.
@ -6157,8 +6175,17 @@ event_handler_read_netlink (NMPlatform *platform, gboolean wait_for_acks)
case -NLE_DUMP_INTR:
_LOGD ("netlink: read: uncritical failure to retrieve incoming events: %s (%d)", nl_geterror (nle), nle);
break;
case -_NLE_MSG_TRUNC:
case -_NLE_NM_NOBUFS:
_LOGI ("netlink: read: too many netlink events. Need to resynchronize platform cache");
_LOGI ("netlink: read: %s. Need to resynchronize platform cache",
({
const char *_reason = "unknown";
switch (nle) {
case -_NLE_MSG_TRUNC: _reason = "message truncated"; break;
case -_NLE_NM_NOBUFS: _reason = "too many netlink events"; break;
}
_reason;
}));
event_handler_recvmsgs (platform, FALSE);
delayed_action_wait_for_nl_response_complete_all (platform, WAIT_FOR_NL_RESPONSE_RESULT_FAILED_RESYNC);
delayed_action_schedule (platform,
@ -6415,6 +6442,12 @@ constructed (GObject *_object)
nle = nl_socket_set_buffer_size (priv->nlh, 8*1024*1024, 0);
g_assert (!nle);
/* explicitly set the msg buffer size and disable MSG_PEEK.
* If we later encounter NLE_MSG_TRUNC, we will adjust the buffer size. */
nl_socket_disable_msg_peek (priv->nlh);
nle = nl_socket_set_msg_buf_size (priv->nlh, 4 * getpagesize ());
g_assert (!nle);
nle = nl_socket_add_memberships (priv->nlh,
RTNLGRP_LINK,
RTNLGRP_IPV4_IFADDR, RTNLGRP_IPV6_IFADDR,