posix-cpu-timers: Split run_posix_cpu_timers()

Split it up as a preparatory step to move the heavy lifting out of
interrupt context.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20200730102337.677439437@linutronix.de

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 1651179..e5ad873 100644 (file)
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1080,32 +1080,15 @@ static inline bool fastpath_timer_check(struct task_struct *tsk)
        return false;
 }
 
-/*
- * This is called from the timer interrupt handler.  The irq handler has
- * already updated our counts.  We need to check if any timers fire now.
- * Interrupts are disabled.
- */
-void run_posix_cpu_timers(void)
+static void __run_posix_cpu_timers(struct task_struct *tsk)
 {
-       struct task_struct *tsk = current;
        struct k_itimer *timer, *next;
        unsigned long flags;
        LIST_HEAD(firing);
 
-       lockdep_assert_irqs_disabled();
-
-       /*
-        * The fast path checks that there are no expired thread or thread
-        * group timers.  If that's so, just return.
-        */
-       if (!fastpath_timer_check(tsk))
+       if (!lock_task_sighand(tsk, &flags))
                return;
 
-       lockdep_posixtimer_enter();
-       if (!lock_task_sighand(tsk, &flags)) {
-               lockdep_posixtimer_exit();
-               return;
-       }
        /*
         * Here we take off tsk->signal->cpu_timers[N] and
         * tsk->cpu_timers[N] all the timers that are firing, and
@@ -1147,6 +1130,28 @@ void run_posix_cpu_timers(void)
                        cpu_timer_fire(timer);
                spin_unlock(&timer->it_lock);
        }
+}
+
+/*
+ * This is called from the timer interrupt handler.  The irq handler has
+ * already updated our counts.  We need to check if any timers fire now.
+ * Interrupts are disabled.
+ */
+void run_posix_cpu_timers(void)
+{
+       struct task_struct *tsk = current;
+
+       lockdep_assert_irqs_disabled();
+
+       /*
+        * The fast path checks that there are no expired thread or thread
+        * group timers.  If that's so, just return.
+        */
+       if (!fastpath_timer_check(tsk))
+               return;
+
+       lockdep_posixtimer_enter();
+       __run_posix_cpu_timers(tsk);
        lockdep_posixtimer_exit();
 }