diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-02-03 16:05:24 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-16 22:30:50 -0700 |
| commit | 5f01a22c5b231dd590f61a2591b3090665733bcb (patch) | |
| tree | 1aa1fc3e72a7a505042fa26306db407a83d356ab /include/linux/user_namespace.h | |
| parent | 328152e6774d9d801ad1d90af557b9113647b379 (diff) | |
ucount: use RCU for ucounts lookups
The ucounts element is looked up under ucounts_lock. This can be
optimized by using RCU for a lockless lookup and return and element if the
reference can be obtained.
Replace hlist_head with hlist_nulls_head which is RCU compatible. Let
find_ucounts() search for the required item within a RCU section and
return the item if a reference could be obtained. This means
alloc_ucounts() will always return an element (unless the memory
allocation failed). Let put_ucounts() RCU free the element if the
reference counter dropped to zero.
Link: https://lkml.kernel.org/r/20250203150525.456525-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mengen Sun <mengensun@tencent.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: YueHong Wu <yuehongwu@tencent.com>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include/linux/user_namespace.h')
| -rw-r--r-- | include/linux/user_namespace.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 7183e5aca282..ad4dbef92597 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -5,6 +5,7 @@ #include <linux/kref.h> #include <linux/nsproxy.h> #include <linux/ns_common.h> +#include <linux/rculist_nulls.h> #include <linux/sched.h> #include <linux/workqueue.h> #include <linux/rwsem.h> @@ -115,9 +116,10 @@ struct user_namespace { } __randomize_layout; struct ucounts { - struct hlist_node node; + struct hlist_nulls_node node; struct user_namespace *ns; kuid_t uid; + struct rcu_head rcu; atomic_t count; atomic_long_t ucount[UCOUNT_COUNTS]; atomic_long_t rlimit[UCOUNT_RLIMIT_COUNTS]; |