92 lines
2.7 KiB
Diff
92 lines
2.7 KiB
Diff
From 7632d1dd96f75bdba997003fa61ab14e57afb0fe Mon Sep 17 00:00:00 2001
|
|
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
Date: Wed, 9 Apr 2014 10:37:23 +0200
|
|
Subject: [PATCH 5/5] block: mq: use cpu_light()
|
|
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.8-rt6.tar.xz
|
|
|
|
there is a might sleep splat because get_cpu() disables preemption and
|
|
later we grab a lock. As a workaround for this we use get_cpu_light()
|
|
and an additional lock to prevent taking the same ctx.
|
|
|
|
There is a lock member in the ctx already but there some functions which do ++
|
|
on the member and this works with irq off but on RT we would need the extra lock.
|
|
|
|
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
|
|
---
|
|
block/blk-mq.c | 4 ++++
|
|
block/blk-mq.h | 17 ++++++++++++++---
|
|
2 files changed, 18 insertions(+), 3 deletions(-)
|
|
|
|
--- a/block/blk-mq.c
|
|
+++ b/block/blk-mq.c
|
|
@@ -1353,7 +1353,9 @@ static void blk_sq_make_request(struct r
|
|
if (list_empty(&plug->mq_list))
|
|
trace_block_plug(q);
|
|
else if (request_count >= BLK_MAX_REQUEST_COUNT) {
|
|
+ spin_unlock(&data.ctx->cpu_lock);
|
|
blk_flush_plug_list(plug, false);
|
|
+ spin_lock(&data.ctx->cpu_lock);
|
|
trace_block_plug(q);
|
|
}
|
|
list_add_tail(&rq->queuelist, &plug->mq_list);
|
|
@@ -1548,6 +1550,7 @@ static int blk_mq_hctx_cpu_offline(struc
|
|
blk_mq_hctx_clear_pending(hctx, ctx);
|
|
}
|
|
spin_unlock(&ctx->lock);
|
|
+ __blk_mq_put_ctx(ctx);
|
|
|
|
if (list_empty(&tmp))
|
|
return NOTIFY_OK;
|
|
@@ -1741,6 +1744,7 @@ static void blk_mq_init_cpu_queues(struc
|
|
memset(__ctx, 0, sizeof(*__ctx));
|
|
__ctx->cpu = i;
|
|
spin_lock_init(&__ctx->lock);
|
|
+ spin_lock_init(&__ctx->cpu_lock);
|
|
INIT_LIST_HEAD(&__ctx->rq_list);
|
|
__ctx->queue = q;
|
|
|
|
--- a/block/blk-mq.h
|
|
+++ b/block/blk-mq.h
|
|
@@ -9,6 +9,7 @@ struct blk_mq_ctx {
|
|
struct list_head rq_list;
|
|
} ____cacheline_aligned_in_smp;
|
|
|
|
+ spinlock_t cpu_lock;
|
|
unsigned int cpu;
|
|
unsigned int index_hw;
|
|
|
|
@@ -76,7 +77,11 @@ struct blk_align_bitmap {
|
|
static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
|
|
unsigned int cpu)
|
|
{
|
|
- return per_cpu_ptr(q->queue_ctx, cpu);
|
|
+ struct blk_mq_ctx *ctx;
|
|
+
|
|
+ ctx = per_cpu_ptr(q->queue_ctx, cpu);
|
|
+ spin_lock(&ctx->cpu_lock);
|
|
+ return ctx;
|
|
}
|
|
|
|
/*
|
|
@@ -87,12 +92,18 @@ static inline struct blk_mq_ctx *__blk_m
|
|
*/
|
|
static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
|
|
{
|
|
- return __blk_mq_get_ctx(q, get_cpu());
|
|
+ return __blk_mq_get_ctx(q, get_cpu_light());
|
|
+}
|
|
+
|
|
+static void __blk_mq_put_ctx(struct blk_mq_ctx *ctx)
|
|
+{
|
|
+ spin_unlock(&ctx->cpu_lock);
|
|
}
|
|
|
|
static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
|
|
{
|
|
- put_cpu();
|
|
+ __blk_mq_put_ctx(ctx);
|
|
+ put_cpu_light();
|
|
}
|
|
|
|
struct blk_mq_alloc_data {
|