On Thursday 19 February 2015 06:49 AM, Lucas De Marchi wrote: > On Wed, Feb 18, 2015 at 8:40 PM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: >> Lucas De Marchi <lucas.de.marchi@xxxxxxxxx> writes: >>> On Wed, Feb 18, 2015 at 2:07 AM, Rusty Russell <rusty@xxxxxxxxxxxxxxx> wrote: >>> Yeah, I just thought (an wanted that) the attributes were being >>> created first and then hooked up in the sysfs tree under >>> /sys/module/<modulename>. I.e. if the directory exists and there's no >>> initstate this is because it's a builtin module. I don't want to >>> wait/sleep on the file to appear because users of >>> kmod_module_get_initstate() may not tolerate this behavior. >>> >>> Looking up at the old module-init-tools, it used an ugly loop with >>> usleep() before trying to read the file again :-/ >>> >>> Can we change kernel side guaranteeing the initstate file appears >>> together with the directory? >> Greg? The core problem is that kmod looks for >> /sys/module/<name>/initstate; if it's not there, it assumes a builtin >> module. > Just to make it clear: > > We try to open /sys/module/<name>/initstate. If it fails we stat > /sys/module/<name> checking if it exists and is a directory. If it > does then we assume the module is builtin. > >> However, this is racy when a module is being inserted. Is there a way >> to create this sysfs file and dir atomically? > Greg, the question is still valid since it'd be nice to have this > guarantee and be able to correctly reply the state with whatever is in > initstate file, but... > > Rusty, thinking again if we fallback to "coming" instead of "builtin" > everything should be fine, no? Because the decision about builtin has > already been taken by looking at the modules.builtin index. If we > return "coming" here the second call to modprobe would call > init_module() again which would wait for the first one to complete (or > return EEXIST if it's already live) since we only shortcut the > init_module() call if the module is live or builtin > > what do you think? > > > Harrish, in your patch if you just change the "return > KMOD_MODULE_BUILTIN;" to "return KMOD_MODULE_COMING;" does it work? > Yes. Returning KMOD_MODULE_COMING instead of KMOD_MODULE_BUILTIN works. The built-in modules are handled by looking at the modules.builtin index file. Is there any chance of returning KMOD_MODULE_COMING for builti-in modules? If it does not have any impact, then the fix should be fine. Do I need to send a separate patch ? -- To unsubscribe from this list: send the line "unsubscribe linux-modules" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
