[OpenWrt-Devel] [RFC] netifd: Crash when netifd reload is handled during netifd startup

[Hans Dedecker]

Hi,

Applied the ubus patch but netifd_reload is still called while
config_init_all is processing the config and thus leading to a crash
when netifd_reload is done

Added extra traces in netifd which confirms this :
un 24 16:00:44 OpenWrt daemon.notice netifd: config_init_all : Enter
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Create interface
'loopback'
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Create simple device
'lo'
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Initialize device 'lo'
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Remove a route from
device lo
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Remove a route from
device lo
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Remove a route from
device lo
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Network device 'lo' is
now present
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Add user for device
'lo', refcount=1
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Interface 'loopback',
available=1
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Add user for device
'lo', refcount=2
Jun 24 16:00:44 OpenWrt daemon.notice netifd: netifd_reload : Enter
Jun 24 16:00:44 OpenWrt daemon.notice netifd: config_init_all : Enter
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Update interface
'loopback'
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Create new device
'br-lan' (Bridge)
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Initialize device
'br-lan'
Jun 24 16:00:44 OpenWrt daemon.notice netifd: Create interface 'lan'
.....
Jun 24 16:00:45 OpenWrt daemon.notice netifd: config_init_all : Exit
Jun 24 16:00:45 OpenWrt daemon.notice netifd: netifd_reload : Exit


Hans
On Tue, Jun 24, 2014 at 2:05 PM, Felix Fietkau <nbd at openwrt.org> wrote:
> On 2014-06-24 12:46, Hans Dedecker wrote:
>> Netifd is crashing when when a network reload (ubus call network reload) is handled during the parsing of the network config in the function config_init_all (called from main) at startup.
>> As an ubus_invoke function call is issued when the interfaces are created; ubus will also process the pending ubus calls in this case the network reload during the invoke.
>> As netifd_reload calls again config_init_all network config will be parsed again; on return from netifd_reload the original config_init_all function call will continue but will crash as references hold to interface/device/etc ... lists are not correct anymore.
>> This potential problem has always been present but due to netifd_reload timing behavior change in netifd commit 5db02763d61785529bef538f196c180e968b7c26 this problem can easily be triggered.
>> To solve the issue I was thinking about deferring the network reload when the function config_init_all is parsing the config.
>> Any opinion if this is the correct way to go or any other alternatives ?
> Please try applying this patch to ubus:
> http://nbd.name/libubus-req-defer.patch
>
> It should ensure that no invoke will be processed while netifd is busy
> with registering/unregistering objects or sending notify calls.
>
> - Felix
_______________________________________________
openwrt-devel mailing list
openwrt-devel at lists.openwrt.org
https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel