81 lines
2.9 KiB
Diff
81 lines
2.9 KiB
Diff
From b27255be28c01c02934220c8e255bbe8bea6e3d7 Mon Sep 17 00:00:00 2001
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Message-Id: <b27255be28c01c02934220c8e255bbe8bea6e3d7.1601675152.git.zanussi@kernel.org>
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In-Reply-To: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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References: <5b5a156f9808b1acf1205606e03da117214549ea.1601675151.git.zanussi@kernel.org>
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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: [PATCH 181/333] md: raid5: Make raid5_percpu handling RT aware
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.148-rt64.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 | 8 +++++---
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drivers/md/raid5.h | 1 +
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2 files changed, 6 insertions(+), 3 deletions(-)
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diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
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index d91154d65455..8d571170cb89 100644
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--- a/drivers/md/raid5.c
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+++ b/drivers/md/raid5.c
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@@ -2069,8 +2069,9 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
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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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@@ -2129,7 +2130,8 @@ static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
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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 void free_stripe(struct kmem_cache *sc, struct stripe_head *sh)
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@@ -6816,6 +6818,7 @@ static int raid456_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
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__func__, cpu);
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return -ENOMEM;
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}
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+ spin_lock_init(&per_cpu_ptr(conf->percpu, cpu)->lock);
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return 0;
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}
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@@ -6826,7 +6829,6 @@ static int raid5_alloc_percpu(struct r5conf *conf)
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conf->percpu = alloc_percpu(struct raid5_percpu);
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if (!conf->percpu)
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return -ENOMEM;
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-
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err = cpuhp_state_add_instance(CPUHP_MD_RAID5_PREPARE, &conf->node);
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if (!err) {
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conf->scribble_disks = max(conf->raid_disks,
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diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
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index 8474c224127b..a3bf907ab2af 100644
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--- a/drivers/md/raid5.h
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+++ b/drivers/md/raid5.h
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@@ -637,6 +637,7 @@ 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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--
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2.17.1
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