From 90d3839b90fe379557dae4a44735a6af78f42885 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 12 Nov 2013 19:42:14 -0800 Subject: block: Use u64_stats_init() to initialize seqcounts Now that seqcounts are lockdep enabled objects, we need to explicitly initialize runtime allocated seqcounts so that lockdep can track them. Without this patch, Fengguang was seeing: [ 4.127282] INFO: trying to register non-static key. [ 4.128027] the code is fine but needs lockdep annotation. [ 4.128027] turning off the locking correctness validator. [ 4.128027] CPU: 0 PID: 96 Comm: kworker/u4:1 Not tainted 3.12.0-next-20131108-10601-gbad570d #2 [ 4.128027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ ... ] [ 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 [ 4.128027] [<794079aa>] ? blk_throtl_bio+0x1c3/0x485 [ 4.128027] [<794079aa>] blk_throtl_bio+0x1c3/0x485 ... Use u64_stats_init() for all affected data structures, which initializes the seqcount. Reported-and-Tested-by: Fengguang Wu Cc: Vivek Goyal Cc: Jens Axboe Signed-off-by: Peter Zijlstra [ Folded in another fix from the mailing list as well as a fix to that fix. Tweaked commit message. ] Signed-off-by: John Stultz Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/1384314134-6895-1-git-send-email-john.stultz@linaro.org [ So I actually think that the two SOBs from PeterZ are the right depiction of the patch route. ] Signed-off-by: Ingo Molnar --- block/blk-throttle.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'block/blk-throttle.c') diff --git a/block/blk-throttle.c b/block/blk-throttle.c index 8331aba9426f..06534049afba 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -256,6 +256,12 @@ static struct throtl_data *sq_to_td(struct throtl_service_queue *sq) } \ } while (0) +static void tg_stats_init(struct tg_stats_cpu *tg_stats) +{ + blkg_rwstat_init(&tg_stats->service_bytes); + blkg_rwstat_init(&tg_stats->serviced); +} + /* * Worker for allocating per cpu stat for tgs. This is scheduled on the * system_wq once there are some groups on the alloc_list waiting for @@ -269,12 +275,16 @@ static void tg_stats_alloc_fn(struct work_struct *work) alloc_stats: if (!stats_cpu) { + int cpu; + stats_cpu = alloc_percpu(struct tg_stats_cpu); if (!stats_cpu) { /* allocation failed, try again after some time */ schedule_delayed_work(dwork, msecs_to_jiffies(10)); return; } + for_each_possible_cpu(cpu) + tg_stats_init(per_cpu_ptr(stats_cpu, cpu)); } spin_lock_irq(&tg_stats_alloc_lock); -- cgit