2024-04-10 22:50:18

by Thomas Gleixner

Subject: [patch V2 19/50] posix-timers: Convert timer list to hlist

No requirement for a real list. Spare a few bytes.

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Frederic Weisbecker <[email protected]>
---
fs/proc/base.c | 6 +++---
include/linux/posix-timers.h | 2 +-
include/linux/sched/signal.h | 2 +-
init/init_task.c | 2 +-
kernel/fork.c | 2 +-
kernel/time/posix-timers.c | 19 ++++++++-----------
6 files changed, 15 insertions(+), 18 deletions(-)

--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2456,13 +2456,13 @@ static void *timers_start(struct seq_fil
if (!tp->sighand)
return ERR_PTR(-ESRCH);

- return seq_list_start(&tp->task->signal->posix_timers, *pos);
+ return seq_hlist_start(&tp->task->signal->posix_timers, *pos);
}

static void *timers_next(struct seq_file *m, void *v, loff_t *pos)
{
struct timers_private *tp = m->private;
- return seq_list_next(v, &tp->task->signal->posix_timers, pos);
+ return seq_hlist_next(v, &tp->task->signal->posix_timers, pos);
}

static void timers_stop(struct seq_file *m, void *v)
@@ -2491,7 +2491,7 @@ static int show_timer(struct seq_file *m
[SIGEV_THREAD] = "thread",
};

- timer = list_entry((struct list_head *)v, struct k_itimer, list);
+ timer = hlist_entry((struct hlist_node *)v, struct k_itimer, list);
notify = timer->it_sigev_notify;

seq_printf(m, "ID: %d\n", timer->it_id);
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -158,7 +158,7 @@ static inline void posix_cputimers_init_
* @rcu: RCU head for freeing the timer.
*/
struct k_itimer {
- struct list_head list;
+ struct hlist_node list;
struct hlist_node t_hash;
spinlock_t it_lock;
const struct k_clock *kclock;
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -137,7 +137,7 @@ struct signal_struct {

/* POSIX.1b Interval Timers */
unsigned int next_posix_timer_id;
- struct list_head posix_timers;
+ struct hlist_head posix_timers;

/* ITIMER_REAL timer for the process */
struct hrtimer real_timer;
--- a/init/init_task.c
+++ b/init/init_task.c
@@ -29,7 +29,7 @@ static struct signal_struct init_signals
.cred_guard_mutex = __MUTEX_INITIALIZER(init_signals.cred_guard_mutex),
.exec_update_lock = __RWSEM_INITIALIZER(init_signals.exec_update_lock),
#ifdef CONFIG_POSIX_TIMERS
- .posix_timers = LIST_HEAD_INIT(init_signals.posix_timers),
+ .posix_timers = HLIST_HEAD_INIT,
.cputimer = {
.cputime_atomic = INIT_CPUTIME_ATOMIC,
},
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1876,7 +1876,7 @@ static int copy_signal(unsigned long clo
prev_cputime_init(&sig->prev_cputime);

#ifdef CONFIG_POSIX_TIMERS
- INIT_LIST_HEAD(&sig->posix_timers);
+ INIT_HLIST_HEAD(&sig->posix_timers);
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
sig->real_timer.function = it_real_fn;
#endif
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -515,7 +515,7 @@ static int do_timer_create(clockid_t whi
spin_lock_irq(&current->sighand->siglock);
/* This makes the timer valid in the hash table */
WRITE_ONCE(new_timer->it_signal, current->signal);
- list_add(&new_timer->list, &current->signal->posix_timers);
+ hlist_add_head(&new_timer->list, &current->signal->posix_timers);
spin_unlock_irq(&current->sighand->siglock);
/*
* After unlocking sighand::siglock @new_timer is subject to
@@ -1025,7 +1025,7 @@ SYSCALL_DEFINE1(timer_delete, timer_t, t
}

spin_lock(&current->sighand->siglock);
- list_del(&timer->list);
+ hlist_del(&timer->list);
spin_unlock(&current->sighand->siglock);
/*
* A concurrent lookup could check timer::it_signal lockless. It
@@ -1075,7 +1075,7 @@ static void itimer_delete(struct k_itime

goto retry_delete;
}
- list_del(&timer->list);
+ hlist_del(&timer->list);

/*
* Setting timer::it_signal to NULL is technically not required
@@ -1096,22 +1096,19 @@ static void itimer_delete(struct k_itime
*/
void exit_itimers(struct task_struct *tsk)
{
- struct list_head timers;
- struct k_itimer *tmr;
+ struct hlist_head timers;

- if (list_empty(&tsk->signal->posix_timers))
+ if (hlist_empty(&tsk->signal->posix_timers))
return;

/* Protect against concurrent read via /proc/$PID/timers */
spin_lock_irq(&tsk->sighand->siglock);
- list_replace_init(&tsk->signal->posix_timers, &timers);
+ hlist_move_list(&tsk->signal->posix_timers, &timers);
spin_unlock_irq(&tsk->sighand->siglock);

/* The timers are not longer accessible via tsk::signal */
- while (!list_empty(&timers)) {
- tmr = list_first_entry(&timers, struct k_itimer, list);
- itimer_delete(tmr);
- }
+ while (!hlist_empty(&timers))
+ itimer_delete(hlist_entry(timers.first, struct k_itimer, list));
}

SYSCALL_DEFINE2(clock_settime, const clockid_t, which_clock,