Messages in this thread | | | Date | Tue, 4 Aug 2020 17:51:20 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] Platform lockdown information in SYSFS |
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On Tue, Aug 04, 2020 at 12:05:25PM -0300, Daniel Gutson wrote: > On Tue, Aug 4, 2020 at 11:43 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > On Tue, Aug 04, 2020 at 11:37:02AM -0300, Daniel Gutson wrote: > > > On Tue, Aug 4, 2020 at 11:23 AM Greg Kroah-Hartman < > > > gregkh@linuxfoundation.org> wrote: > > > > > > > > On Tue, Aug 04, 2020 at 10:50:13AM -0300, Daniel Gutson wrote: > > > > > On Tue, Aug 4, 2020 at 3:41 AM Greg Kroah-Hartman > > > > > <gregkh@linuxfoundation.org> wrote: > > > > > > > > > > > > On Mon, Aug 03, 2020 at 07:04:56PM -0300, Daniel Gutson wrote: > > > > > > > > > > Think of this as an input device. You don't put the random > > > input > > > > > > > > > > attributes all in one place, you create a new device that > > > represents the > > > > > > > > > > input interface and register that. > > > > > > > > > > > > > > I'm having trouble with this. What's the dev_t for the child > > > devices? > > > > > > > I'm doing > > > > > > > child_device = device_create(&my_class, &pdev->dev, MKDEV(0, 0), > > > > > > > NULL, "child"); > > > > > > > pdev is the pci_device (intel-spi-pci) > > > > > > > dmesg shows > > > > > > > > > > > > > > sysfs: cannot create duplicate filename '/class/my-class' > > > > > > > (call trace) > > > > > > > kobject_add_internal failed for my-class with -EEXIST, don't try > > > > > > > to register things with the same name in the same directory. > > > > > > > > > > > > Without seeing all of your code, I can't tell you what you are doing > > > > > > wrong, but the kernel should be giving you a huge hint here... > > > > > > > > > > > > Don't create duplicate names in the same subdirectory. > > > > > > > > > > I'm not doing that. One of my questions is if MKDEV(0, 0) is valid for > > > > > create_device, which I inferred so from the documentation. > > > > > > > > Yes it is, but that's not the error given to you :) > > > > > > > > Many in-kernel users call device_create() with MKDEV(0, 0) > > > > > > > > > Here is the listing > > > > > > > > <snip> > > > > > > > > It's not in any format to read, please never strip leading whitespace, > > > > it hurts my brain... > > > > > > (trying again) > > > Also, this is in pastebin: https://pastebin.com/8Ye9eUm5 > > > > > > #include <linux/kobject.h> > > > #include <linux/sysfs.h> > > > #include <linux/module.h> > > > #include <linux/init.h> > > > #include <linux/list.h> > > > #include <linux/slab.h> > > > #include <linux/device.h> > > > #include <linux/pci.h> > > > > > > static ssize_t howareyou_show(struct class *class, struct class_attribute > > > *attr, > > > char *buf) > > > { > > > return sprintf(buf, "%s\n", "How are you?"); > > > } > > > static CLASS_ATTR_RO(howareyou); > > > > These are rare, as they are "global" for a class, are you sure you want > > that? > > I'm no longer using class attributes, this is from my previous > experiment. Sorry for the confusion. > In the "real" code I'll use DEVICE_ATTR_RO. > > > > > > > > > static struct class my_class = { > > > .name = "my-class", > > > .owner = THIS_MODULE, > > > }; > > > > > > struct device* child_device; > > > > > > static int mypci_probe(struct pci_dev *pdev, > > > const struct pci_device_id *id) > > > { > > > int ret; > > > > > > ret = pcim_enable_device(pdev); > > > if (ret) > > > return ret; > > > > > > ret = class_register(&my_class); > > > if (ret < 0) > > > return ret; > > > > > > > > > pr_info("DFG: Recognized. DID: %lx\n", (unsigned long > > > int)id->driver_data); > > > pr_info("DFG: device DID: %lx\n", (unsigned long int)pdev->device); > > > > > > ret = class_create_file(&my_class, &class_attr_howareyou); > > > if (ret != 0) { > > > pr_err("DFG class create file error: %d\n", ret); > > > class_unregister(&my_class); > > > return ret; > > > } > > > > > > child_device = device_create(&my_class, &pdev->dev, MKDEV(0, 0), > > > NULL, "child"); > > > if (child_device == NULL) { > > > pr_err("DFG error child device NULL"); > > > } > > > > > > return ret; > > > } > > > > > > > > > Looks sane, what does your kernel log say when you load this? > first insmod, OK. > rmmod, OK. > Second insmod: > > [ 4149.389133] sysfs: cannot create duplicate filename > '/devices/pci0000:00/0000:00:1f.0/my-class'
Ok, that means you did not clean up properly.
After rmmod see if you really did clean up all of the directories/files you created.
The kernel is trying to be nice and give you a hint here :)
thanks,
greg k-h
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