[GIT PULL] scheduler fixes

Ingo Molnar
2013-04-14T15:51:56Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched-urgent-for-linus

HEAD: e614b3332a4f3f264a26da28e5a1f4cc3aea3974 sched/cputime: Fix accounting on multi-threaded processes

Misc fixlets.

Thanks,

Ingo

------------------>
Stanislaw Gruszka (1):
sched/cputime: Fix accounting on multi-threaded processes

Tejun Heo (1):
sched: Convert BUG_ON()s in try_to_wake_up_local() to WARN_ON_ONCE()s

Thomas Gleixner (1):
sched_clock: Prevent 64bit inatomicity on 32bit systems

libin (1):
sched/debug: Fix sd->*_idx limit range avoiding overflow

kernel/sched/clock.c | 26 ++++++++++++++++++++++++++
kernel/sched/core.c | 8 +++++---
kernel/sched/cputime.c | 2 +-
3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
index c685e31..c3ae144 100644
--- a/kernel/sched/clock.c
+++ b/kernel/sched/clock.c
@@ -176,10 +176,36 @@ static u64 sched_clock_remote(struct sched_clock_data *scd)
u64 this_clock, remote_clock;
u64 *ptr, old_val, val;

+#if BITS_PER_LONG != 64
+again:
+ /*
+ * Careful here: The local and the remote clock values need to
+ * be read out atomic as we need to compare the values and
+ * then update either the local or the remote side. So the
+ * cmpxchg64 below only protects one readout.
+ *
+ * We must reread via sched_clock_local() in the retry case on
+ * 32bit as an NMI could use sched_clock_local() via the
+ * tracer and hit between the readout of
+ * the low32bit and the high 32bit portion.
+ */
+ this_clock = sched_clock_local(my_scd);
+ /*
+ * We must enforce atomic readout on 32bit, otherwise the
+ * update on the remote cpu can hit inbetween the readout of
+ * the low32bit and the high 32bit portion.
+ */
+ remote_clock = cmpxchg64(&scd->clock, 0, 0);
+#else
+ /*
+ * On 64bit the read of [my]scd->clock is atomic versus the
+ * update, so we can avoid the above 32bit dance.
+ */
sched_clock_local(my_scd);
again:
this_clock = my_scd->clock;
remote_clock = scd->clock;
+#endif

/*
* Use the opportunity that we have both locks
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b7b03cd..fa07792 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1488,8 +1488,10 @@ static void try_to_wake_up_local(struct task_struct *p)
{
struct rq *rq = task_rq(p);

- BUG_ON(rq != this_rq());
- BUG_ON(p == current);
+ if (WARN_ON_ONCE(rq != this_rq()) ||
+ WARN_ON_ONCE(p == current))
+ return;
+
lockdep_assert_held(&rq->lock);

if (!raw_spin_trylock(&p->pi_lock)) {
@@ -4931,7 +4933,7 @@ static void sd_free_ctl_entry(struct ctl_table **tablep)
}

static int min_load_idx = 0;
-static int max_load_idx = CPU_LOAD_IDX_MAX;
+static int max_load_idx = CPU_LOAD_IDX_MAX-1;

static void
set_table_entry(struct ctl_table *entry,
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index ed12cbb..e93cca9 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -310,7 +310,7 @@ void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)

t = tsk;
do {
- task_cputime(tsk, &utime, &stime);
+ task_cputime(t, &utime, &stime);
times->utime += utime;
times->stime += stime;
times->sum_exec_runtime += task_sched_runtime(t);