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![Bruno Prémont](/assets/img/avatar_default.png)
Do not let the kernel crash when a device is registered with sysfs while group attributes are not set (aka NULL). Warn about the offender with some information about the offending device. This would warn instead of trying NULL pointer deref like: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff81152673>] internal_create_group+0x83/0x1a0 PGD 0 Oops: 0000 [#1] SMP CPU 0 Modules linked in: Pid: 1, comm: swapper/0 Not tainted 3.4.0-rc1-x86_64 #3 HP ProLiant DL360 G4 RIP: 0010:[<ffffffff81152673>] [<ffffffff81152673>] internal_create_group+0x83/0x1a0 RSP: 0018:ffff88019485fd70 EFLAGS: 00010202 RAX: 0000000000000001 RBX: 0000000000000000 RCX: 0000000000000001 RDX: ffff880192e99908 RSI: ffff880192e99630 RDI: ffffffff81a26c60 RBP: ffff88019485fdc0 R08: 0000000000000000 R09: 0000000000000000 R10: ffff880192e99908 R11: 0000000000000000 R12: ffffffff81a16a00 R13: ffff880192e99908 R14: ffffffff81a16900 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88019bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 0000000001a0c000 CR4: 00000000000007f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process swapper/0 (pid: 1, threadinfo ffff88019485e000, task ffff880194878000) Stack: ffff88019485fdd0 ffff880192da9d60 0000000000000000 ffff880192e99908 ffff880192e995d8 0000000000000001 ffffffff81a16a00 ffff880192da9d60 0000000000000000 0000000000000000 ffff88019485fdd0 ffffffff811527be Call Trace: [<ffffffff811527be>] sysfs_create_group+0xe/0x10 [<ffffffff81376ca6>] device_add_groups+0x46/0x80 [<ffffffff81377d3d>] device_add+0x46d/0x6a0 ... Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
211 lines
5.4 KiB
C
211 lines
5.4 KiB
C
/*
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* fs/sysfs/group.c - Operations for adding/removing multiple files at once.
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*
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* Copyright (c) 2003 Patrick Mochel
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* Copyright (c) 2003 Open Source Development Lab
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*
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* This file is released undert the GPL v2.
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*
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*/
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/dcache.h>
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#include <linux/namei.h>
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#include <linux/err.h>
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#include "sysfs.h"
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static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
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const struct attribute_group *grp)
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{
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struct attribute *const* attr;
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int i;
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for (i = 0, attr = grp->attrs; *attr; i++, attr++)
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sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
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}
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static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
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const struct attribute_group *grp, int update)
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{
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struct attribute *const* attr;
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int error = 0, i;
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for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
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umode_t mode = 0;
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/* in update mode, we're changing the permissions or
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* visibility. Do this by first removing then
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* re-adding (if required) the file */
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if (update)
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sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
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if (grp->is_visible) {
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mode = grp->is_visible(kobj, *attr, i);
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if (!mode)
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continue;
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}
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error = sysfs_add_file_mode(dir_sd, *attr, SYSFS_KOBJ_ATTR,
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(*attr)->mode | mode);
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if (unlikely(error))
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break;
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}
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if (error)
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remove_files(dir_sd, kobj, grp);
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return error;
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}
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static int internal_create_group(struct kobject *kobj, int update,
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const struct attribute_group *grp)
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{
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struct sysfs_dirent *sd;
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int error;
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BUG_ON(!kobj || (!update && !kobj->sd));
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/* Updates may happen before the object has been instantiated */
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if (unlikely(update && !kobj->sd))
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return -EINVAL;
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if (!grp->attrs) {
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WARN(1, "sysfs: attrs not set by subsystem for group: %s/%s\n",
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kobj->name, grp->name ? "" : grp->name);
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return -EINVAL;
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}
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if (grp->name) {
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error = sysfs_create_subdir(kobj, grp->name, &sd);
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if (error)
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return error;
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} else
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sd = kobj->sd;
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sysfs_get(sd);
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error = create_files(sd, kobj, grp, update);
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if (error) {
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if (grp->name)
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sysfs_remove_subdir(sd);
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}
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sysfs_put(sd);
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return error;
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}
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/**
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* sysfs_create_group - given a directory kobject, create an attribute group
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* @kobj: The kobject to create the group on
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* @grp: The attribute group to create
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*
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* This function creates a group for the first time. It will explicitly
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* warn and error if any of the attribute files being created already exist.
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*
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* Returns 0 on success or error.
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*/
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int sysfs_create_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return internal_create_group(kobj, 0, grp);
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}
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/**
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* sysfs_update_group - given a directory kobject, update an attribute group
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* @kobj: The kobject to update the group on
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* @grp: The attribute group to update
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*
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* This function updates an attribute group. Unlike
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* sysfs_create_group(), it will explicitly not warn or error if any
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* of the attribute files being created already exist. Furthermore,
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* if the visibility of the files has changed through the is_visible()
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* callback, it will update the permissions and add or remove the
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* relevant files.
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*
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* The primary use for this function is to call it after making a change
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* that affects group visibility.
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*
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* Returns 0 on success or error.
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*/
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int sysfs_update_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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return internal_create_group(kobj, 1, grp);
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}
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void sysfs_remove_group(struct kobject * kobj,
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const struct attribute_group * grp)
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{
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struct sysfs_dirent *dir_sd = kobj->sd;
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struct sysfs_dirent *sd;
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if (grp->name) {
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sd = sysfs_get_dirent(dir_sd, NULL, grp->name);
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if (!sd) {
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WARN(!sd, KERN_WARNING "sysfs group %p not found for "
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"kobject '%s'\n", grp, kobject_name(kobj));
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return;
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}
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} else
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sd = sysfs_get(dir_sd);
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remove_files(sd, kobj, grp);
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if (grp->name)
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sysfs_remove_subdir(sd);
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sysfs_put(sd);
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}
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/**
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* sysfs_merge_group - merge files into a pre-existing attribute group.
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* @kobj: The kobject containing the group.
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* @grp: The files to create and the attribute group they belong to.
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*
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* This function returns an error if the group doesn't exist or any of the
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* files already exist in that group, in which case none of the new files
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* are created.
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*/
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int sysfs_merge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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struct sysfs_dirent *dir_sd;
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int error = 0;
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struct attribute *const *attr;
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int i;
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dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
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if (!dir_sd)
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return -ENOENT;
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for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
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error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
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if (error) {
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while (--i >= 0)
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sysfs_hash_and_remove(dir_sd, NULL, (*--attr)->name);
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}
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sysfs_put(dir_sd);
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return error;
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}
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EXPORT_SYMBOL_GPL(sysfs_merge_group);
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/**
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* sysfs_unmerge_group - remove files from a pre-existing attribute group.
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* @kobj: The kobject containing the group.
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* @grp: The files to remove and the attribute group they belong to.
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*/
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void sysfs_unmerge_group(struct kobject *kobj,
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const struct attribute_group *grp)
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{
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struct sysfs_dirent *dir_sd;
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struct attribute *const *attr;
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dir_sd = sysfs_get_dirent(kobj->sd, NULL, grp->name);
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if (dir_sd) {
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for (attr = grp->attrs; *attr; ++attr)
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sysfs_hash_and_remove(dir_sd, NULL, (*attr)->name);
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sysfs_put(dir_sd);
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}
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}
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EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
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EXPORT_SYMBOL_GPL(sysfs_create_group);
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EXPORT_SYMBOL_GPL(sysfs_update_group);
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EXPORT_SYMBOL_GPL(sysfs_remove_group);
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