[OpenWrt-Devel] Mismatch in ubus / uloop options

[Karl Vogel]

In ubus_reconnect, the ctx->sock.fd is created and set to non-blocking mode:

fcntl(ctx->sock.fd, F_SETFL, fcntl(ctx->sock.fd, F_GETFL) | O_NONBLOCK |
> O_CLOEXEC);
>

http://git.openwrt.org/?p=project/ubus.git;a=blob;f=libubus-io.c;h=9d3ac6c33f4d926c7f5c5d2033d531fc5fc6f834;hb=259450f414d8c9ee41896e8e6d6bc57ec00e2b63#l396


However, further in the call stack, the socket will get added to uloop via
ubus_add_uloop with the flag ULOOP_BLOCKING set.

http://git.openwrt.org/?p=project/ubus.git;a=blob;f=libubus.h;h=54e7d481b0496e719f2f567b664a2619c82a3b16;hb=259450f414d8c9ee41896e8e6d6bc57ec00e2b63#l245

ie when called from ubus_complete_request on an !registered ctx->sock, the
ubus_add_uloop is done:

http://git.openwrt.org/?p=project/ubus.git;a=blob;f=libubus-req.c;h=bf19f3670ea5b215190dfcce125c358f616c72a4;hb=259450f414d8c9ee41896e8e6d6bc57ec00e2b63#l136

The uloop function assumes a socket is blocking by default and will never
make a socket blocking again, it will only turn it to non-blocking if
ULOOP_BLOCKING isn't set. This caused a busy loop in some daemons that had
their socket set to non-blocking due to another issue, ie. poll using 0 as
infinite instead of -1, for which I submitted a fix earlier.

I wonder if it wouldn't be better to have uloop set the socket flags in all
cases? Currently it "assumes" the socket is blocking and if ULOOP_BLOCKING
is passed, it will set it to non-blocking, but it won't do the other way
round. Though that might have some impact on daemons that think the socket
is non-blocking while it will be turned into blocking if this is changed.
So not sure what the best way to go about this one is?!


Regards,
Karl
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