/* -*- mode: c; c-basic-offset: 8; -*- * vim: noexpandtab sw=8 ts=8 sts=0: * * symlink.c - operations for configfs symlinks. * * 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 021110-1307, USA. * * Based on sysfs: * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel * * configfs Copyright (C) 2005 Oracle. All rights reserved. */ #include #include #include #include #include #include "configfs_internal.h" /* Protects attachments of new symlinks */ DEFINE_MUTEX(configfs_symlink_mutex); static int item_depth(struct config_item * item) { struct config_item * p = item; int depth = 0; do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p)); return depth; } static int item_path_length(struct config_item * item) { struct config_item * p = item; int length = 1; do { length += strlen(config_item_name(p)) + 1; p = p->ci_parent; } while (p && !configfs_is_root(p)); return length; } static void fill_item_path(struct config_item * item, char * buffer, int length) { struct config_item * p; --length; for (p = item; p && !configfs_is_root(p); p = p->ci_parent) { int cur = strlen(config_item_name(p)); /* back up enough to print this bus id with '/' */ length -= cur; strncpy(buffer + length,config_item_name(p),cur); *(buffer + --length) = '/'; } } static int create_link(struct config_item *parent_item, struct config_item *item, struct dentry *dentry) { struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata; struct configfs_symlink *sl; int ret; ret = -ENOENT; if (!configfs_dirent_is_ready(target_sd)) goto out; ret = -ENOMEM; sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); if (sl) { sl->sl_target = config_item_get(item); spin_lock(&configfs_dirent_lock); if (target_sd->s_type & CONFIGFS_USET_DROPPING) { spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); return -ENOENT; } list_add(&sl->sl_list, &target_sd->s_links); spin_unlock(&configfs_dirent_lock); ret = configfs_create_link(sl, parent_item->ci_dentry, dentry); if (ret) { spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); } } out: return ret; } static int get_target(const char *symname, struct path *path, struct config_item **target, struct super_block *sb) { int ret; ret = kern_path(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, path); if (!ret) { if (path->dentry->d_sb == sb) { *target = configfs_get_config_item(path->dentry); if (!*target) { ret = -ENOENT; path_put(path); } } else { ret = -EPERM; path_put(path); } } return ret; } int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname) { int ret; struct path path; struct configfs_dirent *sd; struct config_item *parent_item; struct config_item *target_item = NULL; struct config_item_type *type; sd = dentry->d_parent->d_fsdata; /* * Fake invisibility if dir belongs to a group/default groups hierarchy * being attached */ ret = -ENOENT; if (!configfs_dirent_is_ready(sd)) goto out; parent_item = configfs_get_config_item(dentry->d_parent); type = parent_item->ci_type; ret = -EPERM; if (!type || !type->ct_item_ops || !type->ct_item_ops->allow_link) goto out_put; ret = get_target(symname, &path, &target_item, dentry->d_sb); if (ret) goto out_put; ret = type->ct_item_ops->allow_link(parent_item, target_item); if (!ret) { mutex_lock(&configfs_symlink_mutex); ret = create_link(parent_item, target_item, dentry); mutex_unlock(&configfs_symlink_mutex); if (ret && type->ct_item_ops->drop_link) type->ct_item_ops->drop_link(parent_item, target_item); } config_item_put(target_item); path_put(&path); out_put: config_item_put(parent_item); out: return ret; } int configfs_unlink(struct inode *dir, struct dentry *dentry) { struct configfs_dirent *sd = dentry->d_fsdata; struct configfs_symlink *sl; struct config_item *parent_item; struct config_item_type *type; int ret; ret = -EPERM; /* What lack-of-symlink returns */ if (!(sd->s_type & CONFIGFS_ITEM_LINK)) goto out; sl = sd->s_element; parent_item = configfs_get_config_item(dentry->d_parent); type = parent_item->ci_type; spin_lock(&configfs_dirent_lock); list_del_init(&sd->s_sibling); spin_unlock(&configfs_dirent_lock); configfs_drop_dentry(sd, dentry->d_parent); dput(dentry); configfs_put(sd); /* * drop_link() must be called before * list_del_init(&sl->sl_list), so that the order of * drop_link(this, target) and drop_item(target) is preserved. */ if (type && type->ct_item_ops && type->ct_item_ops->drop_link) type->ct_item_ops->drop_link(parent_item, sl->sl_target); spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); spin_unlock(&configfs_dirent_lock); /* Put reference from create_link() */ config_item_put(sl->sl_target); kfree(sl); config_item_put(parent_item); ret = 0; out: return ret; } static int configfs_get_target_path(struct config_item * item, struct config_item * target, char *path) { char * s; int depth, size; depth = item_depth(item); size = item_path_length(target) + depth * 3 - 1; if (size > PATH_MAX) return -ENAMETOOLONG; pr_debug("%s: depth = %d, size = %d\n", __func__, depth, size); for (s = path; depth--; s += 3) strcpy(s,"../"); fill_item_path(target, path, size); pr_debug("%s: path = '%s'\n", __func__, path); return 0; } static int configfs_getlink(struct dentry *dentry, char * path) { struct config_item *item, *target_item; int error = 0; item = configfs_get_config_item(dentry->d_parent); if (!item) return -EINVAL; target_item = configfs_get_config_item(dentry); if (!target_item) { config_item_put(item); return -EINVAL; } down_read(&configfs_rename_sem); error = configfs_get_target_path(item, target_item, path); up_read(&configfs_rename_sem); config_item_put(item); config_item_put(target_item); return error; } static const char *configfs_get_link(struct dentry *dentry, struct inode *inode, struct delayed_call *done) { char *body; int error; if (!dentry) return ERR_PTR(-ECHILD); body = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!body) return ERR_PTR(-ENOMEM); error = configfs_getlink(dentry, body); if (!error) { set_delayed_call(done, kfree_link, body); return body; } kfree(body); return ERR_PTR(error); } const struct inode_operations configfs_symlink_inode_operations = { .get_link = configfs_get_link, .setattr = configfs_setattr, }; tomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/lib/symbol/kallsyms.h')