| From b89f469db10e1805ba4f3c12e72f12ffbe6bd16e Mon Sep 17 00:00:00 2001 |
| From: Thomas Gleixner <tglx@linutronix.de> |
| Date: Tue, 6 Apr 2010 16:51:31 +0200 |
| Subject: [PATCH 170/270] md: raid5: Make raid5_percpu handling RT aware |
| |
| __raid_run_ops() disables preemption with get_cpu() around the access |
| to the raid5_percpu variables. That causes scheduling while atomic |
| spews on RT. |
| |
| Serialize the access to the percpu data with a lock and keep the code |
| preemptible. |
| |
| Reported-by: Udo van den Heuvel <udovdh@xs4all.nl> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Tested-by: Udo van den Heuvel <udovdh@xs4all.nl> |
| --- |
| drivers/md/raid5.c | 7 +++++-- |
| drivers/md/raid5.h | 1 + |
| 2 files changed, 6 insertions(+), 2 deletions(-) |
| |
| diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c |
| index 0240576..b6ea794 100644 |
| --- a/drivers/md/raid5.c |
| +++ b/drivers/md/raid5.c |
| @@ -1321,8 +1321,9 @@ static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request) |
| struct raid5_percpu *percpu; |
| unsigned long cpu; |
| |
| - cpu = get_cpu(); |
| + cpu = get_cpu_light(); |
| percpu = per_cpu_ptr(conf->percpu, cpu); |
| + spin_lock(&percpu->lock); |
| if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) { |
| ops_run_biofill(sh); |
| overlap_clear++; |
| @@ -1374,7 +1375,8 @@ static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request) |
| if (test_and_clear_bit(R5_Overlap, &dev->flags)) |
| wake_up(&sh->raid_conf->wait_for_overlap); |
| } |
| - put_cpu(); |
| + spin_unlock(&percpu->lock); |
| + put_cpu_light(); |
| } |
| |
| #ifdef CONFIG_MULTICORE_RAID456 |
| @@ -4772,6 +4774,7 @@ static int raid5_alloc_percpu(struct r5conf *conf) |
| break; |
| } |
| per_cpu_ptr(conf->percpu, cpu)->scribble = scribble; |
| + spin_lock_init(&per_cpu_ptr(conf->percpu, cpu)->lock); |
| } |
| #ifdef CONFIG_HOTPLUG_CPU |
| conf->cpu_notify.notifier_call = raid456_cpu_notify; |
| diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h |
| index 8d8e139..a784311 100644 |
| --- a/drivers/md/raid5.h |
| +++ b/drivers/md/raid5.h |
| @@ -417,6 +417,7 @@ struct r5conf { |
| int recovery_disabled; |
| /* per cpu variables */ |
| struct raid5_percpu { |
| + spinlock_t lock; /* Protection for -RT */ |
| struct page *spare_page; /* Used when checking P/Q in raid6 */ |
| void *scribble; /* space for constructing buffer |
| * lists and performing address |
| -- |
| 1.7.10.4 |
| |