Messages in this thread | | | Date | Tue, 16 Jul 2013 11:29:42 -0700 | From | Srinivas Pandruvada <> | Subject | Re: driver model, duplicate names question |
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Thanks for the quick response. Here I am creating virtual devices using device_register. I have attached a simple test program, which will give error.
This is my intention:
$> cd /sys/class/test_class $> ls power_zone_cpu_package_0 power_zone_cpu_package_1
$> cd power_zone_cpu_package_0 $> ls power-zone-cpu-0
$> cd ..
$> cd power_zone_cpu_package_1 $> ls power-zone-cpu-0
The error will be " Error: sysfs: cannot create duplicate filename '/class/test_class/power-zone-cpu-0'
I want to avoid a flat model, if there is a server system with many CPU packages with multiple cores in each.
Thanks, Srinivas
On 07/16/2013 09:44 AM, Greg KH wrote: > On Tue, Jul 16, 2013 at 09:34:57AM -0700, Srinivas Pandruvada wrote: >> Hi Greg, >> >> I would like to create tree like structure using device model (struct >> device, device_register/device_unregister) using parent/child >> relationship while creation. I want to be able to create duplicate >> names, when their parents are different, similar to a directory structure. >> I see that I can't create devices with duplicate names (device names), >> even when their parents are different. > We actually check that? Nice, I didn't realize that :) > >> How can I allow duplicate names when their parents are different devices? >> I want to avoid flat model as I have parent child relationship and there >> will be too many devices using flat model. > Devices on the same bus shouldn't have the same name, but if they are in > a "tree", it should be ok. What check is erroring out? > >> Why, I need? >> I am going to publish RFC for a new power cap class driver. We have a >> multiple controllers under power cap class (they are devices). Under >> which there are multiple power zones, with parent/child relationships. >> Currently I have to use kobject_init_and_add, which I want to avoid and >> just use device_register. Other places, wherever such relationships are >> required, kobjects are used like cpufreq. > Yes, you shouldn't use "raw" kobject calls at all, so we should fix > this. > > thanks, > > greg k-h >
#include <linux/module.h> #include <linux/device.h> #include <linux/err.h> #include <linux/slab.h>
static struct device dev_par_0; static struct device dev_par_0_child_0;
static struct device dev_par_1; static struct device dev_par_1_child_0;
static struct class test_class_class = { .name = "test_class", };
static int create_test_devices(void) { int result;
dev_set_name(&dev_par_0, "power_zone_cpu_package_0");
dev_par_0.class = &test_class_class; result = device_register(&dev_par_0); if (result) { pr_err("device_register failed for parent_0\n"); return result; } dev_set_name(&dev_par_1, "power_zone_cpu_package_1"); dev_par_1.class = &test_class_class; result = device_register(&dev_par_1); if (result) { pr_err("device_register failed for parent_0\n"); goto error_par1; }
dev_set_name(&dev_par_0_child_0, "power-zone-cpu-0"); dev_par_0_child_0.class = &test_class_class; dev_par_0_child_0.parent = &dev_par_0; result = device_register(&dev_par_0_child_0); if (result) { pr_err("device_register failed for dev_par_0_child_0\n"); goto error_par0_child_0; }
dev_set_name(&dev_par_1_child_0, "power-zone-cpu-0"); dev_par_1_child_0.class = &test_class_class; dev_par_1_child_0.parent = &dev_par_1; result = device_register(&dev_par_1_child_0); if (result) { pr_err("device_register failed for dev_par_1_child_0\n"); goto error_par0_child_1; }
return 0;
error_par0_child_1: device_unregister(&dev_par_0_child_0); error_par0_child_0: device_unregister(&dev_par_1); error_par1: device_unregister(&dev_par_0);
return result; }
static int __init dev_create_test_init(void) { int result = 0;
pr_debug("dev_create_test_init\n"); result = class_register(&test_class_class); if (result) return result;
result = create_test_devices();
return result; }
static void dev_create_test_exit(void) { pr_debug("dev_create_test_exit\n");
device_unregister(&dev_par_0_child_0); device_unregister(&dev_par_1_child_0); device_unregister(&dev_par_0); device_unregister(&dev_par_1);
class_unregister(&test_class_class); }
module_init(dev_create_test_init) module_exit(dev_create_test_exit) MODULE_LICENSE("GPL v2");
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