| From d980cb7b0412055e7a8b561bf111284536444101 Mon Sep 17 00:00:00 2001 |
| From: Thomas Gleixner <tglx@linutronix.de> |
| Date: Tue, 6 Apr 2010 16:51:31 +0200 |
| Subject: [PATCH] raid5: Make raid5_percpu handling RT aware |
| |
| commit d980cb7b0412055e7a8b561bf111284536444101 in tip. |
| |
| __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> |
| |
| diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c |
| index ceb24af..b61eaa6 100644 |
| --- a/drivers/md/raid5.c |
| +++ b/drivers/md/raid5.c |
| @@ -1149,8 +1149,9 @@ static void __raid_run_ops(struct stripe_head *sh, unsigned long ops_request) |
| struct raid5_percpu *percpu; |
| unsigned long cpu; |
| |
| - cpu = get_cpu(); |
| + cpu = raw_smp_processor_id(); |
| 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++; |
| @@ -1202,7 +1203,7 @@ 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); |
| } |
| |
| #ifdef CONFIG_MULTICORE_RAID456 |
| diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h |
| index dd70835..2db71cd 100644 |
| --- a/drivers/md/raid5.h |
| +++ b/drivers/md/raid5.h |
| @@ -400,6 +400,7 @@ struct raid5_private_data { |
| */ |
| /* 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 |
| -- |
| 1.7.1.1 |
| |