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Subject[RFC PATCH 2/6] cpu-timers: cleanup arm_timer()
Date
Updating expiration cache is messed in arm_timer(), clean it up.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
kernel/posix-cpu-timers.c | 104 +++++++++++++++------------------------------
1 files changed, 35 insertions(+), 69 deletions(-)

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 137d991..84589e9 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -546,97 +546,63 @@ static inline int expires_gt(cputime_t expires, cputime_t new_exp)
cputime_gt(expires, new_exp);
}

-static inline int expires_le(cputime_t expires, cputime_t new_exp)
-{
- return !cputime_eq(expires, cputime_zero) &&
- cputime_le(expires, new_exp);
-}
/*
* Insert the timer on the appropriate list before any timers that
* expire later. This must be called with the tasklist_lock held
* for reading, and interrupts disabled.
*/
-static void arm_timer(struct k_itimer *timer, union cpu_time_count now)
+static void arm_timer(struct k_itimer *timer)
{
struct task_struct *p = timer->it.cpu.task;
struct list_head *head, *listpos;
+ struct task_cputime *cputime_expires;
struct cpu_timer_list *const nt = &timer->it.cpu;
struct cpu_timer_list *next;

- head = (CPUCLOCK_PERTHREAD(timer->it_clock) ?
- p->cpu_timers : p->signal->cpu_timers);
+ if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
+ head = p->cpu_timers;
+ cputime_expires = &p->cputime_expires;
+ } else {
+ head = p->signal->cpu_timers;
+ cputime_expires = &p->signal->cputime_expires;
+ }
head += CPUCLOCK_WHICH(timer->it_clock);

BUG_ON(!irqs_disabled());
spin_lock(&p->sighand->siglock);

listpos = head;
- if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {
- list_for_each_entry(next, head, entry) {
- if (next->expires.sched > nt->expires.sched)
- break;
- listpos = &next->entry;
- }
- } else {
- list_for_each_entry(next, head, entry) {
- if (cputime_gt(next->expires.cpu, nt->expires.cpu))
- break;
- listpos = &next->entry;
- }
+ list_for_each_entry(next, head, entry) {
+ if (cpu_time_before(timer->it_clock, nt->expires, next->expires))
+ break;
+ listpos = &next->entry;
}
list_add(&nt->entry, listpos);

if (listpos == head) {
+ union cpu_time_count *exp = &nt->expires;
+
/*
- * We are the new earliest-expiring timer.
- * If we are a thread timer, there can always
- * be a process timer telling us to stop earlier.
+ * We are the new earliest-expiring POSIX 1.b timer, hence
+ * need to update expiration cache. Take into account that
+ * for process timers we share expiration cache with itimers
+ * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
*/

- if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
- union cpu_time_count *exp = &nt->expires;
-
- switch (CPUCLOCK_WHICH(timer->it_clock)) {
- default:
- BUG();
- case CPUCLOCK_PROF:
- if (expires_gt(p->cputime_expires.prof_exp,
- exp->cpu))
- p->cputime_expires.prof_exp = exp->cpu;
- break;
- case CPUCLOCK_VIRT:
- if (expires_gt(p->cputime_expires.virt_exp,
- exp->cpu))
- p->cputime_expires.virt_exp = exp->cpu;
- break;
- case CPUCLOCK_SCHED:
- if (p->cputime_expires.sched_exp == 0 ||
- p->cputime_expires.sched_exp > exp->sched)
- p->cputime_expires.sched_exp =
- exp->sched;
- break;
- }
- } else {
- struct signal_struct *const sig = p->signal;
- union cpu_time_count *exp = &timer->it.cpu.expires;
-
- /*
- * For a process timer, set the cached expiration time.
- */
- switch (CPUCLOCK_WHICH(timer->it_clock)) {
- default:
- BUG();
- case CPUCLOCK_VIRT:
- if (expires_gt(sig->cputime_expires.virt_exp, exp->cpu))
- sig->cputime_expires.virt_exp = exp->cpu;
- case CPUCLOCK_PROF:
- if (expires_gt(sig->cputime_expires.prof_exp, exp->cpu))
- sig->cputime_expires.prof_exp = exp->cpu;
- break;
- case CPUCLOCK_SCHED:
- sig->cputime_expires.sched_exp = exp->sched;
- break;
- }
+ switch (CPUCLOCK_WHICH(timer->it_clock)) {
+ case CPUCLOCK_PROF:
+ if (expires_gt(cputime_expires->prof_exp, exp->cpu))
+ cputime_expires->prof_exp = exp->cpu;
+ break;
+ case CPUCLOCK_VIRT:
+ if (expires_gt(cputime_expires->virt_exp, exp->cpu))
+ cputime_expires->virt_exp = exp->cpu;
+ break;
+ case CPUCLOCK_SCHED:
+ if (cputime_expires->sched_exp == 0 ||
+ cputime_expires->sched_exp > exp->sched)
+ cputime_expires->sched_exp = exp->sched;
+ break;
}
}

@@ -818,7 +784,7 @@ int posix_cpu_timer_set(struct k_itimer *timer, int flags,
if (new_expires.sched != 0 &&
(timer->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE &&
cpu_time_before(timer->it_clock, val, new_expires)) {
- arm_timer(timer, val);
+ arm_timer(timer);
}

read_unlock(&tasklist_lock);
@@ -1278,7 +1244,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer)
/*
* Now re-arm for the new expiry time.
*/
- arm_timer(timer, now);
+ arm_timer(timer);

out_unlock:
read_unlock(&tasklist_lock);
--
1.6.2.5


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