diff options
Diffstat (limited to 'debian/patches-rt/0309-sched-migrate_enable-Use-stop_one_cpu_nowait.patch')
| -rw-r--r-- | debian/patches-rt/0309-sched-migrate_enable-Use-stop_one_cpu_nowait.patch | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/debian/patches-rt/0309-sched-migrate_enable-Use-stop_one_cpu_nowait.patch b/debian/patches-rt/0309-sched-migrate_enable-Use-stop_one_cpu_nowait.patch new file mode 100644 index 000000000..21108241b --- /dev/null +++ b/debian/patches-rt/0309-sched-migrate_enable-Use-stop_one_cpu_nowait.patch @@ -0,0 +1,121 @@ +From 778702cffc4e8e3f002716b84944ddf23692639f Mon Sep 17 00:00:00 2001 +From: Scott Wood <swood@redhat.com> +Date: Sat, 12 Oct 2019 01:52:14 -0500 +Subject: [PATCH 309/347] sched: migrate_enable: Use stop_one_cpu_nowait() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +[ Upstream commit 6b39a1fa8c53cae08dc03afdae193b7d3a78a173 ] + +migrate_enable() can be called with current->state != TASK_RUNNING. +Avoid clobbering the existing state by using stop_one_cpu_nowait(). +Since we're stopping the current cpu, we know that we won't get +past __schedule() until migration_cpu_stop() has run (at least up to +the point of migrating us to another cpu). + +Signed-off-by: Scott Wood <swood@redhat.com> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> +--- + include/linux/stop_machine.h | 2 ++ + kernel/sched/core.c | 23 +++++++++++++---------- + kernel/stop_machine.c | 7 +++++-- + 3 files changed, 20 insertions(+), 12 deletions(-) + +diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h +index ccdaa8fd5657..150e886ed83d 100644 +--- a/include/linux/stop_machine.h ++++ b/include/linux/stop_machine.h +@@ -26,6 +26,8 @@ struct cpu_stop_work { + cpu_stop_fn_t fn; + void *arg; + struct cpu_stop_done *done; ++ /* Did not run due to disabled stopper; for nowait debug checks */ ++ bool disabled; + }; + + int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); +diff --git a/kernel/sched/core.c b/kernel/sched/core.c +index de6514e13e0c..dff9d26a8625 100644 +--- a/kernel/sched/core.c ++++ b/kernel/sched/core.c +@@ -990,6 +990,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, + struct migration_arg { + struct task_struct *task; + int dest_cpu; ++ bool done; + }; + + /* +@@ -1025,6 +1026,11 @@ static int migration_cpu_stop(void *data) + struct task_struct *p = arg->task; + struct rq *rq = this_rq(); + struct rq_flags rf; ++ int dest_cpu = arg->dest_cpu; ++ ++ /* We don't look at arg after this point. */ ++ smp_mb(); ++ arg->done = true; + + /* + * The original target CPU might have gone down and we might +@@ -1047,9 +1053,9 @@ static int migration_cpu_stop(void *data) + */ + if (task_rq(p) == rq) { + if (task_on_rq_queued(p)) +- rq = __migrate_task(rq, &rf, p, arg->dest_cpu); ++ rq = __migrate_task(rq, &rf, p, dest_cpu); + else +- p->wake_cpu = arg->dest_cpu; ++ p->wake_cpu = dest_cpu; + } + rq_unlock(rq, &rf); + raw_spin_unlock(&p->pi_lock); +@@ -7316,6 +7322,7 @@ void migrate_enable(void) + WARN_ON(smp_processor_id() != cpu); + if (!is_cpu_allowed(p, cpu)) { + struct migration_arg arg = { p }; ++ struct cpu_stop_work work; + struct rq_flags rf; + + rq = task_rq_lock(p, &rf); +@@ -7323,15 +7330,11 @@ void migrate_enable(void) + arg.dest_cpu = select_fallback_rq(cpu, p); + task_rq_unlock(rq, p, &rf); + +- preempt_lazy_enable(); +- preempt_enable(); +- +- sleeping_lock_inc(); +- stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg); +- sleeping_lock_dec(); ++ stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop, ++ &arg, &work); + tlb_migrate_finish(p->mm); +- +- return; ++ __schedule(true); ++ WARN_ON_ONCE(!arg.done && !work.disabled); + } + + out: +diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c +index 067cb83f37ea..2d15c0d50625 100644 +--- a/kernel/stop_machine.c ++++ b/kernel/stop_machine.c +@@ -86,8 +86,11 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work) + enabled = stopper->enabled; + if (enabled) + __cpu_stop_queue_work(stopper, work, &wakeq); +- else if (work->done) +- cpu_stop_signal_done(work->done); ++ else { ++ work->disabled = true; ++ if (work->done) ++ cpu_stop_signal_done(work->done); ++ } + raw_spin_unlock_irqrestore(&stopper->lock, flags); + + wake_up_q(&wakeq); +-- +2.36.1 + |