Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull scheduler fixes from Ingo Molnar:
 "Misc fixes:

   - fix rq->lock lockdep annotation bug

   - fix/improve update_curr_rt() and update_curr_dl() accounting

   - update documentation

   - remove unused macro"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cpufreq: Remove unused SUGOV_KTHREAD_PRIORITY macro
  sched/core: Fix DEBUG_SPINLOCK annotation for rq->lock
  sched/rt: Make update_curr_rt() more accurate
  sched/deadline: Make update_curr_dl() more accurate
  membarrier-sync-core: Document architecture support

diff --git a/Documentation/features/sched/membarrier-sync-core/arch-support.txt b/Documentation/features/sched/membarrier-sync-core/arch-support.txt
new file mode 100644 (file)
index 0000000..2c815a7
--- /dev/null
+++ b/Documentation/features/sched/membarrier-sync-core/arch-support.txt
@@ -0,0 +1,62 @@
+#
+# Feature name:          membarrier-sync-core
+#         Kconfig:       ARCH_HAS_MEMBARRIER_SYNC_CORE
+#         description:   arch supports core serializing membarrier
+#
+# Architecture requirements
+#
+# * arm64
+#
+# Rely on eret context synchronization when returning from IPI handler, and
+# when returning to user-space.
+#
+# * x86
+#
+# x86-32 uses IRET as return from interrupt, which takes care of the IPI.
+# However, it uses both IRET and SYSEXIT to go back to user-space. The IRET
+# instruction is core serializing, but not SYSEXIT.
+#
+# x86-64 uses IRET as return from interrupt, which takes care of the IPI.
+# However, it can return to user-space through either SYSRETL (compat code),
+# SYSRETQ, or IRET.
+#
+# Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely
+# instead on write_cr3() performed by switch_mm() to provide core serialization
+# after changing the current mm, and deal with the special case of kthread ->
+# uthread (temporarily keeping current mm into active_mm) by issuing a
+# sync_core_before_usermode() in that specific case.
+#
+    -----------------------
+    |         arch |status|
+    -----------------------
+    |       alpha: | TODO |
+    |         arc: | TODO |
+    |         arm: | TODO |
+    |       arm64: |  ok  |
+    |    blackfin: | TODO |
+    |         c6x: | TODO |
+    |        cris: | TODO |
+    |         frv: | TODO |
+    |       h8300: | TODO |
+    |     hexagon: | TODO |
+    |        ia64: | TODO |
+    |        m32r: | TODO |
+    |        m68k: | TODO |
+    |       metag: | TODO |
+    |  microblaze: | TODO |
+    |        mips: | TODO |
+    |     mn10300: | TODO |
+    |       nios2: | TODO |
+    |    openrisc: | TODO |
+    |      parisc: | TODO |
+    |     powerpc: | TODO |
+    |        s390: | TODO |
+    |       score: | TODO |
+    |          sh: | TODO |
+    |       sparc: | TODO |
+    |        tile: | TODO |
+    |          um: | TODO |
+    |   unicore32: | TODO |
+    |         x86: |  ok  |
+    |      xtensa: | TODO |
+    -----------------------

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bf724c1..e7c535e 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2601,19 +2601,31 @@ static inline void finish_task(struct task_struct *prev)
 #endif
 }
 
-static inline void finish_lock_switch(struct rq *rq)
+static inline void
+prepare_lock_switch(struct rq *rq, struct task_struct *next, struct rq_flags *rf)
 {
+       /*
+        * Since the runqueue lock will be released by the next
+        * task (which is an invalid locking op but in the case
+        * of the scheduler it's an obvious special-case), so we
+        * do an early lockdep release here:
+        */
+       rq_unpin_lock(rq, rf);
+       spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
 #ifdef CONFIG_DEBUG_SPINLOCK
        /* this is a valid case when another task releases the spinlock */
-       rq->lock.owner = current;
+       rq->lock.owner = next;
 #endif
+}
+
+static inline void finish_lock_switch(struct rq *rq)
+{
        /*
         * If we are tracking spinlock dependencies then we have to
         * fix up the runqueue lock - which gets 'carried over' from
         * prev into current:
         */
        spin_acquire(&rq->lock.dep_map, 0, 0, _THIS_IP_);
-
        raw_spin_unlock_irq(&rq->lock);
 }
 
@@ -2844,14 +2856,7 @@ context_switch(struct rq *rq, struct task_struct *prev,
 
        rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
 
-       /*
-        * Since the runqueue lock will be released by the next
-        * task (which is an invalid locking op but in the case
-        * of the scheduler it's an obvious special-case), so we
-        * do an early lockdep release here:
-        */
-       rq_unpin_lock(rq, rf);
-       spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
+       prepare_lock_switch(rq, next, rf);
 
        /* Here we just switch the register state and the stack. */
        switch_to(prev, next, prev);

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index dd062a1..7936f54 100644 (file)
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -19,8 +19,6 @@
 
 #include "sched.h"
 
-#define SUGOV_KTHREAD_PRIORITY 50
-
 struct sugov_tunables {
        struct gov_attr_set attr_set;
        unsigned int rate_limit_us;

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 9bb0e0c..9df0978 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1153,6 +1153,7 @@ static void update_curr_dl(struct rq *rq)
        struct sched_dl_entity *dl_se = &curr->dl;
        u64 delta_exec, scaled_delta_exec;
        int cpu = cpu_of(rq);
+       u64 now;
 
        if (!dl_task(curr) || !on_dl_rq(dl_se))
                return;
@@ -1165,7 +1166,8 @@ static void update_curr_dl(struct rq *rq)
         * natural solution, but the full ramifications of this
         * approach need further study.
         */
-       delta_exec = rq_clock_task(rq) - curr->se.exec_start;
+       now = rq_clock_task(rq);
+       delta_exec = now - curr->se.exec_start;
        if (unlikely((s64)delta_exec <= 0)) {
                if (unlikely(dl_se->dl_yielded))
                        goto throttle;
@@ -1178,7 +1180,7 @@ static void update_curr_dl(struct rq *rq)
        curr->se.sum_exec_runtime += delta_exec;
        account_group_exec_runtime(curr, delta_exec);
 
-       curr->se.exec_start = rq_clock_task(rq);
+       curr->se.exec_start = now;
        cgroup_account_cputime(curr, delta_exec);
 
        sched_rt_avg_update(rq, delta_exec);

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 663b235..aad4945 100644 (file)
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -950,12 +950,13 @@ static void update_curr_rt(struct rq *rq)
 {
        struct task_struct *curr = rq->curr;
        struct sched_rt_entity *rt_se = &curr->rt;
-       u64 now = rq_clock_task(rq);
        u64 delta_exec;
+       u64 now;
 
        if (curr->sched_class != &rt_sched_class)
                return;
 
+       now = rq_clock_task(rq);
        delta_exec = now - curr->se.exec_start;
        if (unlikely((s64)delta_exec <= 0))
                return;