Re: [seqcount] INFO: trying to register non-static key.

[Peter Zijlstra]

On Mon, Nov 11, 2013 at 09:29:27AM +0800, Fengguang Wu wrote:
> Greetings,
> 
> I got the below dmesg and the first bad commit is
> 
> commit 1ca7d67cf5d5a2aef26a8d9afd789006fa098347
> Author: John Stultz <john.stultz@xxxxxxxxxx>
> Date:   Mon Oct 7 15:51:59 2013 -0700
> 
>     seqcount: Add lockdep functionality to seqcount/seqlock structures
>

> [    4.124336] uli526x: ULi M5261/M5263 net driver, version 0.9.3 (2005-7-29)
> [    4.128027] Call Trace:
> [    4.128027]  [<7908e744>] ? console_unlock+0x353/0x380
> [    4.128027]  [<79dc7cf2>] dump_stack+0x48/0x60
> [    4.128027]  [<7908953e>] __lock_acquire.isra.26+0x7e3/0xceb
> [    4.128027]  [<7908a1c5>] lock_acquire+0x71/0x9a
> [    4.128027]  [<794079aa>] ? blk_throtl_bio+0x1c3/0x485
> [    4.128027]  [<7940658b>] throtl_update_dispatch_stats+0x7c/0x153

The below seems to compile with i386-defconfig + CONFIG_CFQ_GROUP_IOSCHED=y

No idea if it runs properly or not; I seem to have misplaced my i386
root filesystem.

---
Subject: block: Employ u64_stats_init()

Now that seqcounts are lockdep tracked thingies, we need to properly
initialize them, otherwise bad stuff happens.

Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
 block/blk-cgroup.h  | 10 ++++++++++
 block/cfq-iosched.c | 25 +++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index ae6969a7ffd4..1610b22edf09 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -402,6 +402,11 @@ struct request_list *__blk_queue_next_rl(struct request_list *rl,
 #define blk_queue_for_each_rl(rl, q)	\
 	for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 
+static inline void blkg_stat_init(struct blkg_stat *stat)
+{
+	u64_stats_init(&stat->syncp);
+}
+
 /**
  * blkg_stat_add - add a value to a blkg_stat
  * @stat: target blkg_stat
@@ -458,6 +463,11 @@ static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
 	blkg_stat_add(to, blkg_stat_read(from));
 }
 
+static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
+{
+	u64_stats_init(&rwstat->syncp);
+}
+
 /**
  * blkg_rwstat_add - add a value to a blkg_rwstat
  * @rwstat: target blkg_rwstat
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 434944cbd761..4d5cec1ad80d 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1508,6 +1508,29 @@ static void cfq_init_cfqg_base(struct cfq_group *cfqg)
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
+static void cfqg_stats_init(struct cfqg_stats *stats)
+{
+	blkg_rwstat_init(&stats->service_bytes);
+	blkg_rwstat_init(&stats->serviced);
+	blkg_rwstat_init(&stats->merged);
+	blkg_rwstat_init(&stats->service_time);
+	blkg_rwstat_init(&stats->wait_time);
+	blkg_rwstat_init(&stats->queued);
+
+	blkg_stat_init(&stats->sectors);
+	blkg_stat_init(&stats->time);
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+	blkg_stat_init(&stats->unaccounted_time);
+	blkg_stat_init(&stats->avg_queue_size_sum);
+	blkg_stat_init(&stats->avg_queue_size_samples);
+	blkg_stat_init(&stats->dequeue);
+	blkg_stat_init(&stats->group_wait_time);
+	blkg_stat_init(&stats->idle_time);
+	blkg_stat_init(&stats->empty_time);
+#endif
+}
+
 static void cfq_pd_init(struct blkcg_gq *blkg)
 {
 	struct cfq_group *cfqg = blkg_to_cfqg(blkg);
@@ -1515,6 +1538,8 @@ static void cfq_pd_init(struct blkcg_gq *blkg)
 	cfq_init_cfqg_base(cfqg);
 	cfqg->weight = blkg->blkcg->cfq_weight;
 	cfqg->leaf_weight = blkg->blkcg->cfq_leaf_weight;
+	cfqg_stats_init(&cfqg->stats);
+	cfqg_stats_init(&cfqg->dead_stats);
 }
 
 static void cfq_pd_offline(struct blkcg_gq *blkg)
--
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