timers: fix itimer/many thread hang, v3

- fix UP lockup
- another set of UP/SMP cleanups and simplifications

Signed-off-by: Frank Mayhar <fmayhar@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 38 insertions, 89 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 260c22cc530a..29a3152c45db 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4046,7 +4046,6 @@ unsigned long long task_delta_exec(struct task_struct *p)
         unsigned long flags;
         u64 ns = 0;
 
-        rq = task_rq_lock(p, &flags);
         if (task_current(rq, p)) {
                 u64 delta_exec;
 
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index d6903bd0c7a8..b8c156979cf2 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -276,133 +276,83 @@ sched_info_switch(struct task_struct *prev, struct task_struct *next)
  * on CONFIG_SCHEDSTATS.
  */
 
-#ifdef CONFIG_SMP
-
 /**
- * thread_group_cputime_account_user - Maintain utime for a thread group.
+ * account_group_user_time - Maintain utime for a thread group.
  *
- * @tgtimes:    Pointer to thread_group_cputime structure.
- * @cputime:    Time value by which to increment the utime field of that
- *              structure.
+ * @tsk:        Pointer to task structure.
+ * @cputime:    Time value by which to increment the utime field of the
+ *              thread_group_cputime structure.
  *
  * If thread group time is being maintained, get the structure for the
  * running CPU and update the utime field there.
  */
-static inline void thread_group_cputime_account_user(
-        struct thread_group_cputime *tgtimes,
-        cputime_t cputime)
+static inline void account_group_user_time(struct task_struct *tsk,
+                                           cputime_t cputime)
 {
-        if (tgtimes->totals) {
+        struct signal_struct *sig;
+
+        sig = tsk->signal;
+        if (unlikely(!sig))
+                return;
+        if (sig->cputime.totals) {
                 struct task_cputime *times;
 
-                times = per_cpu_ptr(tgtimes->totals, get_cpu());
+                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
                 times->utime = cputime_add(times->utime, cputime);
                 put_cpu_no_resched();
         }
 }
 
 /**
- * thread_group_cputime_account_system - Maintain stime for a thread group.
+ * account_group_system_time - Maintain stime for a thread group.
  *
- * @tgtimes:    Pointer to thread_group_cputime structure.
- * @cputime:    Time value by which to increment the stime field of that
- *              structure.
+ * @tsk:        Pointer to task structure.
+ * @cputime:    Time value by which to increment the stime field of the
+ *              thread_group_cputime structure.
  *
  * If thread group time is being maintained, get the structure for the
  * running CPU and update the stime field there.
  */
-static inline void thread_group_cputime_account_system(
-        struct thread_group_cputime *tgtimes,
-        cputime_t cputime)
+static inline void account_group_system_time(struct task_struct *tsk,
+                                             cputime_t cputime)
 {
-        if (tgtimes->totals) {
+        struct signal_struct *sig;
+
+        sig = tsk->signal;
+        if (unlikely(!sig))
+                return;
+        if (sig->cputime.totals) {
                 struct task_cputime *times;
 
-                times = per_cpu_ptr(tgtimes->totals, get_cpu());
+                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
                 times->stime = cputime_add(times->stime, cputime);
                 put_cpu_no_resched();
         }
 }
 
 /**
- * thread_group_cputime_account_exec_runtime - Maintain exec runtime for a
- *                                              thread group.
+ * account_group_exec_runtime - Maintain exec runtime for a thread group.
  *
- * @tgtimes:    Pointer to thread_group_cputime structure.
+ * @tsk:        Pointer to task structure.
  * @ns:         Time value by which to increment the sum_exec_runtime field
- *              of that structure.
+ *              of the thread_group_cputime structure.
  *
  * If thread group time is being maintained, get the structure for the
  * running CPU and update the sum_exec_runtime field there.
  */
-static inline void thread_group_cputime_account_exec_runtime(
-        struct thread_group_cputime *tgtimes,
-        unsigned long long ns)
+static inline void account_group_exec_runtime(struct task_struct *tsk,
+                                              unsigned long long ns)
 {
-        if (tgtimes->totals) {
+        struct signal_struct *sig;
+
+        sig = tsk->signal;
+        if (unlikely(!sig))
+                return;
+        if (sig->cputime.totals) {
                 struct task_cputime *times;
 
-                times = per_cpu_ptr(tgtimes->totals, get_cpu());
+                times = per_cpu_ptr(sig->cputime.totals, get_cpu());
                 times->sum_exec_runtime += ns;
                 put_cpu_no_resched();
         }
 }
-
-#else /* CONFIG_SMP */
-
-static inline void thread_group_cputime_account_user(
-        struct thread_group_cputime *tgtimes,
-        cputime_t cputime)
-{
-        tgtimes->totals->utime = cputime_add(tgtimes->totals->utime, cputime);
-}
-
-static inline void thread_group_cputime_account_system(
-        struct thread_group_cputime *tgtimes,
-        cputime_t cputime)
-{
-        tgtimes->totals->stime = cputime_add(tgtimes->totals->stime, cputime);
-}
-
-static inline void thread_group_cputime_account_exec_runtime(
-        struct thread_group_cputime *tgtimes,
-        unsigned long long ns)
-{
-        tgtimes->totals->sum_exec_runtime += ns;
-}
-
-#endif /* CONFIG_SMP */
-
-/*
- * These are the generic time-accounting routines that use the above
- * functions.  They are the functions actually called by the scheduler.
- */
-static inline void account_group_user_time(struct task_struct *tsk,
-                                            cputime_t cputime)
-{
-        struct signal_struct *sig;
-
-        sig = tsk->signal;
-        if (likely(sig))
-                thread_group_cputime_account_user(&sig->cputime, cputime);
-}
-
-static inline void account_group_system_time(struct task_struct *tsk,
-                                              cputime_t cputime)
-{
-        struct signal_struct *sig;
-
-        sig = tsk->signal;
-        if (likely(sig))
-                thread_group_cputime_account_system(&sig->cputime, cputime);
-}
-
-static inline void account_group_exec_runtime(struct task_struct *tsk,
-                                               unsigned long long ns)
-{
-        struct signal_struct *sig;
-
-        sig = tsk->signal;
-        if (likely(sig))
-                thread_group_cputime_account_exec_runtime(&sig->cputime, ns);
-}