Hi, Systemd strips out NLMSG_DONE piece from a multi-part message adding into the receive queue only the messages containing actual data.
If we send a request to the kernel for getting the forwarding database table (just an example), the response will be a multi-part message like below: 1. FDB entry 1; 2. FDB entry 2; 3. NLMSG_DONE; libsystemd strips out "3. NLMSG_DONE;" part and places into the receive queue a pointer to "1. FDB entry 1;". But if the FDB table is empty, the respose from the kernel will look like below: 1. NLMSG_DONE; libsystemd strips out "1. NLMSG_DONE;" part and since there is no actual data got, it continues waiting until reaching timeout. Therefore, a call to "sd_rtnl_call" to send and wait for a response from kernel will exit with timeout which is interpreted as error in communication. The patch I've attached, adds "1. NLMSG_DONE;" to the receive queue only when getting empty response from kernel. This way, a call like "sd_rtnl_call" will not block anymore. It works fine, but it may be just an workaround. Let me know what you think. Alin Rauta (1): libsystemd doesn't handle properly empty messages from kernel src/libsystemd/sd-rtnl/rtnl-message.c | 4 +++- src/libsystemd/sd-rtnl/rtnl-types.c | 1 + src/libsystemd/sd-rtnl/sd-rtnl.c | 14 ++++++++++++++ 3 files changed, 18 insertions(+), 1 deletion(-) -- 1.9.3 _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
