kernel/linux.git/fs/sysfs/dir.c, branch v6.18.21

kernfs: Use RCU to access kernfs_node::name.

2025-02-15T16:46:32+00:00

Using RCU lifetime rules to access kernfs_node::name can avoid the trouble with kernfs_rename_lock in kernfs_name() and kernfs_path_from_node() if the fs was created with KERNFS_ROOT_INVARIANT_PARENT. This is usefull as it allows to implement kernfs_path_from_node() only with RCU protection and avoiding kernfs_rename_lock. The lock is only required if the __parent node can be changed and the function requires an unchanged hierarchy while it iterates from the node to its parent. The change is needed to allow the lookup of the node's path (kernfs_path_from_node()) from context which runs always with disabled preemption and or interrutps even on PREEMPT_RT. The problem is that kernfs_rename_lock becomes a sleeping lock on PREEMPT_RT. I went through all ::name users and added the required access for the lookup with a few extensions: - rdtgroup_pseudo_lock_create() drops all locks and then uses the name later on. resctrl supports rename with different parents. Here I made a temporal copy of the name while it is used outside of the lock. - kernfs_rename_ns() accepts NULL as new_parent. This simplifies sysfs_move_dir_ns() where it can set NULL in order to reuse the current name. - kernfs_rename_ns() is only using kernfs_rename_lock if the parents are different. All users use either kernfs_rwsem (for stable path view) or just RCU for the lookup. The ::name uses always RCU free. Use RCU lifetime guarantees to access kernfs_node::name. Suggested-by: Tejun Heo Acked-by: Tejun Heo Reported-by: syzbot+6ea37e2e6ffccf41a7e6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/67251dc6.050a0220.529b6.015e.GAE@google.com/ Reported-by: Hillf Danton Closes: https://lore.kernel.org/20241102001224.2789-1-hdanton@sina.com Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250213145023.2820193-7-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

fs/sysfs/dir.c : Fix typo in comment

2023-12-07T02:35:23+00:00

Typo correction kboject => kobject Signed-off-by: Mukesh Ojha Link: https://lore.kernel.org/r/1698661274-32540-1-git-send-email-quic_mojha@quicinc.com Signed-off-by: Greg Kroah-Hartman

fs/sysfs/dir.c: replace S_IRWXU|S_IRUGO|S_IXUGO with 0755 sysfs_create_dir_ns()

2021-10-05T14:35:05+00:00

If one ends up expanding on this line checkpatch will complain that the combination S_IRWXU|S_IRUGO|S_IXUGO should just be replaced with the octal 0755. Do that. This makes no functional changes. Signed-off-by: Luis Chamberlain Link: https://lore.kernel.org/r/20210927163805.808907-9-mcgrof@kernel.org Signed-off-by: Greg Kroah-Hartman

docs: filesystems: fix renamed references

2020-04-20T21:45:22+00:00

Some filesystem references got broken by a previous patch series I submitted. Address those. Signed-off-by: Mauro Carvalho Chehab Acked-by: David Sterba # fs/affs/Kconfig Link: https://lore.kernel.org/r/57318c53008dbda7f6f4a5a9e5787f4d37e8565a.1586881715.git.mchehab+huawei@kernel.org Signed-off-by: Jonathan Corbet

sysfs: convert BUG_ON to WARN_ON

2019-01-07T07:53:32+00:00

It's rude to crash the system just because the developer did something wrong, as it prevents them from usually even seeing what went wrong. So convert the few BUG_ON() calls that have snuck into the sysfs code over the years to WARN_ON() to make it more "friendly". All of these are able to be recovered from, so it makes no sense to crash. Reported-by: Linus Torvalds Reviewed-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman

sysfs, kobject: allow creating kobject belonging to arbitrary users

2018-07-21T06:44:35+00:00

Normally kobjects and their sysfs representation belong to global root, however it is not necessarily the case for objects in separate namespaces. For example, objects in separate network namespace logically belong to the container's root and not global root. This change lays groundwork for allowing network namespace objects ownership to be transferred to container's root user by defining get_ownership() callback in ktype structure and using it in sysfs code to retrieve desired uid/gid when creating sysfs objects for given kobject. Co-Developed-by: Tyler Hicks Signed-off-by: Dmitry Torokhov Signed-off-by: Tyler Hicks Signed-off-by: David S. Miller

kernfs: allow creating kernfs objects with arbitrary uid/gid

2018-07-21T06:44:35+00:00

This change allows creating kernfs files and directories with arbitrary uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments. The "simple" kernfs_create_file() and kernfs_create_dir() are left alone and always create objects belonging to the global root. When creating symlinks ownership (uid/gid) is taken from the target kernfs object. Co-Developed-by: Tyler Hicks Signed-off-by: Dmitry Torokhov Signed-off-by: Tyler Hicks Signed-off-by: David S. Miller

sysfs: remove DEBUG defines

2018-01-23T09:19:23+00:00

It isn't needed at all in these files, dynamic debug is the best way to enable this type of thing, if you really want it. As it is, these defines were not doing anything at all. Signed-off-by: Greg Kroah-Hartman

sysfs: use SPDX identifiers

2018-01-23T09:19:10+00:00

Move the license "mark" of the sysfs files to be in SPDX form, instead of the custom text that it currently is in. This is in a quest to get rid of the 700+ different ways we say "GPLv2" in the kernel tree. Signed-off-by: Greg Kroah-Hartman

sysfs: turn WARN() into pr_warn()

2018-01-22T15:11:12+00:00

It's not good to crash the machine if panic_on_warn() is set just because someone made a stupid mistake of trying to create a sysfs file with the same name of an existing one. This makes the automated testing tools a lot harder to find the real bugs in the kernel. So just print a warning out and dump the stack to get the attention of the developer that they did something foolish. Then keep on trucking, as this should not be a fatal error at all. Reported-by: Dmitry Vyukov Signed-off-by: Greg Kroah-Hartman