On 30.03.2016 22:25, Alan Stern wrote:
On Wed, 30 Mar 2016, Ivaylo Dimitrov wrote:
seems to be created twice :). Maybe the problem is that the first time
musb-hdrc is probed it fails with -EPROBE_DEFER, however that failure is
after gadget drivers got loaded and noone unloads them.
gadget drivers will get added to a pending list, then later they'll
bind. But they shouldn't bind() twice, unless there are multiple
interfaces for them.
Well, then it seems we have problem, as the 2 unbind() calls are with
one and the same "common" pointer (again, from memory).
Just some wild guesses based on my memories as I've lost the logs (power
outage). For sure I can recreate them if needed.
okay.
I will redo dump_stack() and printks and will provide logs as soon as I
have some time, so to stop counting on my memories.
Please find attached the relevant logs. It really seems that g_nokia is
probed twice, with all the gadgets in it created two times. I am
starting to suspect 855ed04a3758b205e84b269f92d26ab36ed8e2f7 ("usb:
gadget: udc-core: independent registration of gadgets and gadget
drivers") has something to do with the problem, though reverting it
resulted in g_nokia not being probed at all :)
The problem is not caused by nokia_bind() getting called twice. The
log clearly shows that nokia_bind() is called only once, but it calls
usb_add_config() from two different places:
Jan 1 02:00:10 Nokia-N900 kernel: [ 8.002838] [<c040c5b4>] (usb_add_config) from [<c041b274>] (nokia_bind+0x160/0x2f0)
Jan 1 02:00:10 Nokia-N900 kernel: [ 8.014526] [<c041b274>] (nokia_bind) from [<c040e128>] (composite_bind+0x68/0x1a0)
...
Jan 1 02:00:10 Nokia-N900 kernel: [ 8.381286] [<c040c5b4>] (usb_add_config) from [<c041b28c>] (nokia_bind+0x178/0x2f0)
Jan 1 02:00:10 Nokia-N900 kernel: [ 8.394348] [<c041b28c>] (nokia_bind) from [<c040e128>] (composite_bind+0x68/0x1a0)
Everything else along the two pathways is the same, so this is where
the multiple binds come from. And indeed, looking at the code in
nokia_bind() you can see the two calls:
/* finally register the configuration */
status = usb_add_config(cdev, &nokia_config_500ma_driver,
nokia_bind_config);
if (status < 0)
goto err_msg_luns;
status = usb_add_config(cdev, &nokia_config_100ma_driver,
nokia_bind_config);
Right, somehow I've overslept there are two different nokia_bind+XXX values.
This isn't supposed to cause any problems. The two instances should
never run at the same time, because they belong to different configs.
The problem seems to be that fsg driver creates a thread for every
fsg_bind() call, which overwrites common->thread_task without first
checking if a thread is already created. I don't know the idea behind -
should it have only one thread for all instances, or there should be a
thread per instance, but anyway the current implementation looks wrong.
Ivo
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