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seqlock: Change thread_group_cputime() to use scoped_seqlock_read() 

To simplify the code and make it more readable.

While at it, change thread_group_cputime() to use __for_each_thread(sig).

[peterz: update to new interface]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Oleg Nesterov 2025-10-08 14:30:52 +02:00 committed by Peter Zijlstra
parent cc39f3872c
commit 488f48b326
1 changed files with 5 additions and 15 deletions
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20
kernel/sched/cputime.c
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@ -313,10 +313,8 @@ static u64 read_sum_exec_runtime(struct task_struct *t)
void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
{
struct signal_struct *sig = tsk->signal;
u64 utime, stime;
struct task_struct *t;
unsigned int seq, nextseq;
unsigned long flags;
u64 utime, stime;
/*
* Update current task runtime to account pending time since last
@ -329,27 +327,19 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
if (same_thread_group(current, tsk))
(void) task_sched_runtime(current);
rcu_read_lock();
/* Attempt a lockless read on the first round. */
nextseq = 0;
do {
seq = nextseq;
flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
guard(rcu)();
scoped_seqlock_read (&sig->stats_lock, ss_lock_irqsave) {
times->utime = sig->utime;
times->stime = sig->stime;
times->sum_exec_runtime = sig->sum_sched_runtime;
for_each_thread(tsk, t) {
__for_each_thread(sig, t) {
task_cputime(t, &utime, &stime);
times->utime += utime;
times->stime += stime;
times->sum_exec_runtime += read_sum_exec_runtime(t);
}
/* If lockless access failed, take the lock. */
nextseq = 1;
} while (need_seqretry(&sig->stats_lock, seq));
done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
rcu_read_unlock();
}
}
#ifdef CONFIG_IRQ_TIME_ACCOUNTING