63 lines
2.0 KiB
Diff
63 lines
2.0 KiB
Diff
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Tue, 6 Apr 2010 16:51:31 +0200
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Subject: md: raid5: Make raid5_percpu handling RT aware
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.1/patches-4.1.3-rt3.tar.xz
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__raid_run_ops() disables preemption with get_cpu() around the access
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to the raid5_percpu variables. That causes scheduling while atomic
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spews on RT.
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Serialize the access to the percpu data with a lock and keep the code
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preemptible.
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Reported-by: Udo van den Heuvel <udovdh@xs4all.nl>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Tested-by: Udo van den Heuvel <udovdh@xs4all.nl>
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---
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drivers/md/raid5.c | 7 +++++--
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drivers/md/raid5.h | 1 +
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2 files changed, 6 insertions(+), 2 deletions(-)
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--- a/drivers/md/raid5.c
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+++ b/drivers/md/raid5.c
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@@ -1918,8 +1918,9 @@ static void raid_run_ops(struct stripe_h
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struct raid5_percpu *percpu;
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unsigned long cpu;
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- cpu = get_cpu();
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+ cpu = get_cpu_light();
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percpu = per_cpu_ptr(conf->percpu, cpu);
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+ spin_lock(&percpu->lock);
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if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
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ops_run_biofill(sh);
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overlap_clear++;
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@@ -1975,7 +1976,8 @@ static void raid_run_ops(struct stripe_h
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if (test_and_clear_bit(R5_Overlap, &dev->flags))
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wake_up(&sh->raid_conf->wait_for_overlap);
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}
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- put_cpu();
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+ spin_unlock(&percpu->lock);
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+ put_cpu_light();
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}
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static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp)
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@@ -6350,6 +6352,7 @@ static int raid5_alloc_percpu(struct r5c
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__func__, cpu);
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break;
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}
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+ spin_lock_init(&per_cpu_ptr(conf->percpu, cpu)->lock);
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}
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put_online_cpus();
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--- a/drivers/md/raid5.h
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+++ b/drivers/md/raid5.h
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@@ -494,6 +494,7 @@ struct r5conf {
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int recovery_disabled;
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/* per cpu variables */
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struct raid5_percpu {
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+ spinlock_t lock; /* Protection for -RT */
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struct page *spare_page; /* Used when checking P/Q in raid6 */
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struct flex_array *scribble; /* space for constructing buffer
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* lists and performing address
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