| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Sat, 3 May 2014 11:00:29 +0200 |
| Subject: blk-mq: revert raw locks, post pone notifier to POST_DEAD |
| |
| The blk_mq_cpu_notify_lock should be raw because some CPU down levels |
| are called with interrupts off. The notifier itself calls currently one |
| function that is blk_mq_hctx_notify(). |
| That function acquires the ctx->lock lock which is sleeping and I would |
| prefer to keep it that way. That function only moves IO-requests from |
| the CPU that is going offline to another CPU and it is currently the |
| only one. Therefore I revert the list lock back to sleeping spinlocks |
| and let the notifier run at POST_DEAD time. |
| |
| Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| --- |
| block/blk-mq-cpu.c | 17 ++++++++++------- |
| block/blk-mq.c | 2 +- |
| 2 files changed, 11 insertions(+), 8 deletions(-) |
| |
| --- a/block/blk-mq-cpu.c |
| +++ b/block/blk-mq-cpu.c |
| @@ -16,7 +16,7 @@ |
| #include "blk-mq.h" |
| |
| static LIST_HEAD(blk_mq_cpu_notify_list); |
| -static DEFINE_RAW_SPINLOCK(blk_mq_cpu_notify_lock); |
| +static DEFINE_SPINLOCK(blk_mq_cpu_notify_lock); |
| |
| static int blk_mq_main_cpu_notify(struct notifier_block *self, |
| unsigned long action, void *hcpu) |
| @@ -25,7 +25,10 @@ static int blk_mq_main_cpu_notify(struct |
| struct blk_mq_cpu_notifier *notify; |
| int ret = NOTIFY_OK; |
| |
| - raw_spin_lock(&blk_mq_cpu_notify_lock); |
| + if (action != CPU_POST_DEAD) |
| + return NOTIFY_OK; |
| + |
| + spin_lock(&blk_mq_cpu_notify_lock); |
| |
| list_for_each_entry(notify, &blk_mq_cpu_notify_list, list) { |
| ret = notify->notify(notify->data, action, cpu); |
| @@ -33,7 +36,7 @@ static int blk_mq_main_cpu_notify(struct |
| break; |
| } |
| |
| - raw_spin_unlock(&blk_mq_cpu_notify_lock); |
| + spin_unlock(&blk_mq_cpu_notify_lock); |
| return ret; |
| } |
| |
| @@ -41,16 +44,16 @@ void blk_mq_register_cpu_notifier(struct |
| { |
| BUG_ON(!notifier->notify); |
| |
| - raw_spin_lock(&blk_mq_cpu_notify_lock); |
| + spin_lock(&blk_mq_cpu_notify_lock); |
| list_add_tail(¬ifier->list, &blk_mq_cpu_notify_list); |
| - raw_spin_unlock(&blk_mq_cpu_notify_lock); |
| + spin_unlock(&blk_mq_cpu_notify_lock); |
| } |
| |
| void blk_mq_unregister_cpu_notifier(struct blk_mq_cpu_notifier *notifier) |
| { |
| - raw_spin_lock(&blk_mq_cpu_notify_lock); |
| + spin_lock(&blk_mq_cpu_notify_lock); |
| list_del(¬ifier->list); |
| - raw_spin_unlock(&blk_mq_cpu_notify_lock); |
| + spin_unlock(&blk_mq_cpu_notify_lock); |
| } |
| |
| void blk_mq_init_cpu_notifier(struct blk_mq_cpu_notifier *notifier, |
| --- a/block/blk-mq.c |
| +++ b/block/blk-mq.c |
| @@ -1687,7 +1687,7 @@ static int blk_mq_hctx_notify(void *data |
| { |
| struct blk_mq_hw_ctx *hctx = data; |
| |
| - if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
| + if (action == CPU_POST_DEAD) |
| return blk_mq_hctx_cpu_offline(hctx, cpu); |
| |
| /* |