posix_cpu_timers: consolidate expired timers check

Consolidate the common code amongst per thread and per process timers list
on tick time.

List traversal, expiry check and subsequent updates can be shared in a
common helper.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Olivier Langlois <olivier@trillion01.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 33 insertions, 85 deletions

diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index b1450cee6d6d..92a4fbf44f86 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -862,6 +862,28 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
         }
 }
 
+static unsigned long long
+check_timers_list(struct list_head *timers,
+                  struct list_head *firing,
+                  unsigned long long curr)
+{
+        int maxfire = 20;
+
+        while (!list_empty(timers)) {
+                struct cpu_timer_list *t;
+
+                t = list_first_entry(timers, struct cpu_timer_list, entry);
+
+                if (!--maxfire || curr < t->expires)
+                        return t->expires;
+
+                t->firing = 1;
+                list_move_tail(&t->entry, firing);
+        }
+
+        return 0;
+}
+
 /*
  * Check for any per-thread CPU timers that have fired and move them off
  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
@@ -870,54 +892,20 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp)
 static void check_thread_timers(struct task_struct *tsk,
                                 struct list_head *firing)
 {
-        int maxfire;
         struct list_head *timers = tsk->cpu_timers;
         struct signal_struct *const sig = tsk->signal;
+        struct task_cputime *tsk_expires = &tsk->cputime_expires;
+        unsigned long long expires;
         unsigned long soft;
 
-        maxfire = 20;
-        tsk->cputime_expires.prof_exp = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *t = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || prof_ticks(tsk) < t->expires) {
-                        tsk->cputime_expires.prof_exp = expires_to_cputime(t->expires);
-                        break;
-                }
-                t->firing = 1;
-                list_move_tail(&t->entry, firing);
-        }
+        expires = check_timers_list(timers, firing, prof_ticks(tsk));
+        tsk_expires->prof_exp = expires_to_cputime(expires);
 
-        ++timers;
-        maxfire = 20;
-        tsk->cputime_expires.virt_exp = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *t = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || virt_ticks(tsk) < t->expires) {
-                        tsk->cputime_expires.virt_exp = expires_to_cputime(t->expires);
-                        break;
-                }
-                t->firing = 1;
-                list_move_tail(&t->entry, firing);
-        }
+        expires = check_timers_list(++timers, firing, virt_ticks(tsk));
+        tsk_expires->virt_exp = expires_to_cputime(expires);
 
-        ++timers;
-        maxfire = 20;
-        tsk->cputime_expires.sched_exp = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *t = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || tsk->se.sum_exec_runtime < t->expires) {
-                        tsk->cputime_expires.sched_exp = t->expires;
-                        break;
-                }
-                t->firing = 1;
-                list_move_tail(&t->entry, firing);
-        }
+        tsk_expires->sched_exp = check_timers_list(++timers, firing,
+                                                   tsk->se.sum_exec_runtime);
 
         /*
          * Check for the special case thread timers.
@@ -1002,7 +990,6 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 static void check_process_timers(struct task_struct *tsk,
                                  struct list_head *firing)
 {
-        int maxfire;
         struct signal_struct *const sig = tsk->signal;
         unsigned long long utime, ptime, virt_expires, prof_expires;
         unsigned long long sum_sched_runtime, sched_expires;
@@ -1017,49 +1004,10 @@ static void check_process_timers(struct task_struct *tsk,
         utime = cputime_to_expires(cputime.utime);
         ptime = utime + cputime_to_expires(cputime.stime);
         sum_sched_runtime = cputime.sum_exec_runtime;
-        maxfire = 20;
-        prof_expires = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *tl = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || ptime < tl->expires) {
-                        prof_expires = tl->expires;
-                        break;
-                }
-                tl->firing = 1;
-                list_move_tail(&tl->entry, firing);
-        }
 
-        ++timers;
-        maxfire = 20;
-        virt_expires = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *tl = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || utime < tl->expires) {
-                        virt_expires = tl->expires;
-                        break;
-                }
-                tl->firing = 1;
-                list_move_tail(&tl->entry, firing);
-        }
-
-        ++timers;
-        maxfire = 20;
-        sched_expires = 0;
-        while (!list_empty(timers)) {
-                struct cpu_timer_list *tl = list_first_entry(timers,
-                                                      struct cpu_timer_list,
-                                                      entry);
-                if (!--maxfire || sum_sched_runtime < tl->expires) {
-                        sched_expires = tl->expires;
-                        break;
-                }
-                tl->firing = 1;
-                list_move_tail(&tl->entry, firing);
-        }
+        prof_expires = check_timers_list(timers, firing, ptime);
+        virt_expires = check_timers_list(++timers, firing, utime);
+        sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
 
         /*
          * Check for the special case process timers.