Hi All, I am trying to learn adding entry in proc file system and currently using the the example given in Documentation/DocBook/procfs_example.c. I would like to make a entry in the proc file system that will print the struct timespec values on read i.e. cat . I am getting the following error on compilation and am confused as everything looks ok to me. I was wondering if you guys could please help me. /home/vipul/linux/ldd/test/procfs_example.c: In function ‘proc_read_xtime’: /home/vipul/linux/ldd/test/procfs_example.c:68: warning: ‘tv.tv_sec’ is used uninitialized in this function /home/vipul/linux/ldd/test/procfs_example.c:68: warning: ‘tv.tv_nsec’ is used uninitialized in this function Building modules, stage 2. Regards, Vipul.
/* * procfs_example.c: an example proc interface * * Copyright (C) 2001, Erik Mouw (mouw@xxxxxxxxxxxx) * * This file accompanies the procfs-guide in the Linux kernel * source. Its main use is to demonstrate the concepts and * functions described in the guide. * * This software has been developed while working on the LART * computing board (http://www.lartmaker.nl), which was sponsored * by the Delt University of Technology projects Mobile Multi-media * Communications and Ubiquitous Communications. * * This program is free software; you can redistribute * it and/or modify it under the terms of the GNU General * Public License as published by the Free Software * Foundation; either version 2 of the License, or (at your * option) any later version. * * This program is distributed in the hope that it will be * useful, but WITHOUT ANY WARRANTY; without even the implied * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR * PURPOSE. See the GNU General Public License for more * details. * * You should have received a copy of the GNU General Public * License along with this program; if not, write to the * Free Software Foundation, Inc., 59 Temple Place, * Suite 330, Boston, MA 02111-1307 USA * */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/jiffies.h> #include <asm/uaccess.h> #include <linux/time.h> //#include <linux/timex.h> #define MODULE_VERS "1.0" #define MODULE_NAME "procfs_example" #define FOOBAR_LEN 8 struct fb_data_t { char name[FOOBAR_LEN + 1]; char value[FOOBAR_LEN + 1]; }; static struct proc_dir_entry *xtime_file, *example_dir, *foo_file, *bar_file, *jiffies_file, *symlink; struct fb_data_t foo_data, bar_data; static int proc_read_xtime(char *page, char **start, off_t off, int count, int *eof, void *data) { int len; struct timespec tv; len = sprintf(page, "xtime : tv_secs = %ld tv_nvsecs = %ld \n", (long)tv.tv_sec, tv.tv_nsec); return len; } static int proc_read_jiffies(char *page, char **start, off_t off, int count, int *eof, void *data) { int len; len = sprintf(page, "jiffies = %ld\n", jiffies); return len; } static int proc_read_foobar(char *page, char **start, off_t off, int count, int *eof, void *data) { int len; struct fb_data_t *fb_data = (struct fb_data_t *)data; /* DON'T DO THAT - buffer overruns are bad */ len = sprintf(page, "%s = '%s'\n", fb_data->name, fb_data->value); return len; } static int proc_write_foobar(struct file *file, const char *buffer, unsigned long count, void *data) { int len; struct fb_data_t *fb_data = (struct fb_data_t *)data; if(count > FOOBAR_LEN) len = FOOBAR_LEN; else len = count; if(copy_from_user(fb_data->value, buffer, len)) return -EFAULT; fb_data->value[len] = '\0'; return len; } static int __init init_procfs_example(void) { int rv = 0; /* create directory */ example_dir = proc_mkdir(MODULE_NAME, NULL); if(example_dir == NULL) { rv = -ENOMEM; goto out; } example_dir->owner = THIS_MODULE; /* create jiffies using convenience function */ jiffies_file = create_proc_read_entry("jiffies", 0444, example_dir, proc_read_jiffies, NULL); if(jiffies_file == NULL) { rv = -ENOMEM; goto no_jiffies; } jiffies_file->owner = THIS_MODULE; xtime_file = create_proc_entry("xtime", 0644, example_dir); if(foo_file == NULL) { rv = -ENOMEM; goto no_xtime; } //strcpy(foo_data.name, "foo"); //strcpy(foo_data.value, "foo"); //foo_file->data = &foo_data; xtime_file->read_proc = proc_read_xtime; xtime_file->owner = THIS_MODULE; //foo_file->write_proc = proc_write_foobar; /* create foo and bar files using same callback * functions */ foo_file = create_proc_entry("foo", 0644, example_dir); if(foo_file == NULL) { rv = -ENOMEM; goto no_foo; } strcpy(foo_data.name, "foo"); strcpy(foo_data.value, "foo"); foo_file->data = &foo_data; foo_file->read_proc = proc_read_foobar; foo_file->write_proc = proc_write_foobar; foo_file->owner = THIS_MODULE; bar_file = create_proc_entry("bar", 0644, example_dir); if(bar_file == NULL) { rv = -ENOMEM; goto no_bar; } strcpy(bar_data.name, "bar"); strcpy(bar_data.value, "bar"); bar_file->data = &bar_data; bar_file->read_proc = proc_read_foobar; bar_file->write_proc = proc_write_foobar; bar_file->owner = THIS_MODULE; /* create symlink */ symlink = proc_symlink("jiffies_too", example_dir, "jiffies"); if(symlink == NULL) { rv = -ENOMEM; goto no_symlink; } symlink->owner = THIS_MODULE; /* everything OK */ printk(KERN_INFO "%s %s initialised\n", MODULE_NAME, MODULE_VERS); return 0; no_xtime: remove_proc_entry("xtime", example_dir); no_symlink: remove_proc_entry("bar", example_dir); no_bar: remove_proc_entry("foo", example_dir); no_foo: remove_proc_entry("jiffies", example_dir); no_jiffies: remove_proc_entry(MODULE_NAME, NULL); out: return rv; } static void __exit cleanup_procfs_example(void) { remove_proc_entry("jiffies_too", example_dir); remove_proc_entry("bar", example_dir); remove_proc_entry("xtime", example_dir); remove_proc_entry("foo", example_dir); remove_proc_entry("jiffies", example_dir); remove_proc_entry(MODULE_NAME, NULL); printk(KERN_INFO "%s %s removed\n", MODULE_NAME, MODULE_VERS); } module_init(init_procfs_example); module_exit(cleanup_procfs_example); MODULE_AUTHOR("Erik Mouw"); MODULE_DESCRIPTION("procfs examples"); MODULE_LICENSE("GPL");
