diff options
| author | Christian Brauner <brauner@kernel.org> | 2026-07-10 11:33:05 +0200 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-08-03 10:08:32 +0200 |
| commit | 7a8b81e8b9c73cfb7343fe90e575ec0c31a0c47a (patch) | |
| tree | ca45f77f0f83f04e65235950f5549d7c970206ea /include/linux | |
| parent | b8206f516fe7cbe785cf44bf09c17c438d7c3cad (diff) | |
binfmt_misc: convert entry list to an hlist
The upcoming conversion of the handler lookup to RCU walks cannot use
list_del_init(): reinitializing the forward pointer of a removed entry
would make a concurrent lockless walker standing on that entry loop
back onto it indefinitely. The removal paths do rely on
reinitialization though because bm_{entry,status}_write() and
bm_evict_inode() need to detect whether an entry has already been
unlinked.
hlists support exactly this pattern: hlist_del_init_rcu() keeps the
forward pointer of the removed entry intact for concurrent walkers and
only zeroes ->pprev with hlist_unhashed() serving as the linked test.
Convert the entry list to an hlist now while keeping the rwlock so the
subsequent RCU conversion is a pure locking change. hlist_add_head()
inserts at the head just as list_add() did so lookup precedence
between registered handlers is unchanged.
Link: https://patch.msgid.link/20260710-work-binfmt_misc-locking-v3-4-a162f7cb58d6@kernel.org
Reviewed-by: Jori Koolstra <jkoolstra@xs4all.nl>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/binfmts.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index 2c77e383e737..071da63f2b48 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -101,7 +101,7 @@ struct linux_binfmt { #if IS_ENABLED(CONFIG_BINFMT_MISC) struct binfmt_misc { - struct list_head entries; + struct hlist_head entries; rwlock_t entries_lock; bool enabled; } __randomize_layout; |