Hi Michał,
W dniu 07.04.2016 o 18:40, Michal Nazarewicz pisze:
On Thu, 7 Apr 2016, Michal Nazarewicz wrote:
This makes me suspect it’s not possible to link a function instance to
the same configuration twice, but now that I think about it, I’m not
quite sure what would happen if one did:
ln -s functions/mass_storage.0 configs/c.1/foo
ln -s functions/mass_storage.0 configs/c.1/bar
On Thu, Apr 07 2016, Alan Stern wrote:
Do you think it would be worthwhile to check for this possibility in
the driver and report an error?
I think this should be (if it isn’t already) blocked on configfs side.
I cannot see a legitimate use of such configuration and I wouldn’t be
surprised if other function drivers broke as well.
Sorry about late response.
The function responsible for verifying if a symlink can be made is
in drivers/usb/gadget/configfs.c: config_usb_cfg_link()
There is a comment from the author:
/*
* Make sure this function is from within our _this_ gadget and not
* from another gadget or a random directory.
* Also a function instance can only be linked once.
*/
This is the code fragment of interest:
list_for_each_entry(f, &cfg->func_list, list) {
if (f->fi == fi) {
ret = -EEXIST;
goto out;
}
}
AP
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