diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-02-03 16:05:25 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-16 22:30:50 -0700 |
| commit | b4dc0bee2a749083028afba346910e198653f42a (patch) | |
| tree | 6cca8e505189d9fde61d736a4f8dd605891b40de /kernel/ucount.c | |
| parent | 5f01a22c5b231dd590f61a2591b3090665733bcb (diff) | |
ucount: use rcuref_t for reference counting
Use rcuref_t for reference counting. This eliminates the cmpxchg loop in
the get and put path. This also eliminates the need to acquire the lock
in the put path because once the final user returns the reference, it can
no longer be obtained anymore.
Use rcuref_t for reference counting.
Link: https://lkml.kernel.org/r/20250203150525.456525-5-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 'kernel/ucount.c')
| -rw-r--r-- | kernel/ucount.c | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/kernel/ucount.c b/kernel/ucount.c index b6abaf68cdcc..8686e329b8f2 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -11,7 +11,7 @@ struct ucounts init_ucounts = { .ns = &init_user_ns, .uid = GLOBAL_ROOT_UID, - .count = ATOMIC_INIT(1), + .count = RCUREF_INIT(1), }; #define UCOUNTS_HASHTABLE_BITS 10 @@ -138,7 +138,7 @@ static struct ucounts *find_ucounts(struct user_namespace *ns, kuid_t uid, guard(rcu)(); hlist_nulls_for_each_entry_rcu(ucounts, pos, hashent, node) { if (uid_eq(ucounts->uid, uid) && (ucounts->ns == ns)) { - if (atomic_inc_not_zero(&ucounts->count)) + if (rcuref_get(&ucounts->count)) return ucounts; } } @@ -154,13 +154,6 @@ static void hlist_add_ucounts(struct ucounts *ucounts) spin_unlock_irq(&ucounts_lock); } -struct ucounts *get_ucounts(struct ucounts *ucounts) -{ - if (atomic_inc_not_zero(&ucounts->count)) - return ucounts; - return NULL; -} - struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) { struct hlist_nulls_head *hashent = ucounts_hashentry(ns, uid); @@ -176,7 +169,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid) new->ns = ns; new->uid = uid; - atomic_set(&new->count, 1); + rcuref_init(&new->count, 1); spin_lock_irq(&ucounts_lock); ucounts = find_ucounts(ns, uid, hashent); @@ -196,7 +189,8 @@ void put_ucounts(struct ucounts *ucounts) { unsigned long flags; - if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) { + if (rcuref_put(&ucounts->count)) { + spin_lock_irqsave(&ucounts_lock, flags); hlist_nulls_del_rcu(&ucounts->node); spin_unlock_irqrestore(&ucounts_lock, flags); |