lkml.org 
[lkml]   [2017]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 2/2] blk-mq: don't use WORK_CPU_UNBOUND
Date
cpumask is the list of CPUs present when the queue is built.
If a new CPU is hotplugged, this list is not updated,
and when the scheduler asks for a CPU id, blk_mq_hctx_next_cpu()
can return WORK_CPU_UNBOUND.
And in this case _blk_mq_run_hw_queue() can be executed by the new CPU
(that is not present in cpumask) and raises the following warning:

WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
cpu_online(hctx->next_cpu));

To fix this problem, this patch modifies blk_mq_hctx_next_cpu()
to only return a CPU id present in cpumask.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
block/blk-mq.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4603b115e234..bdac1e654814 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1126,9 +1126,6 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
*/
static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
{
- if (hctx->queue->nr_hw_queues == 1)
- return WORK_CPU_UNBOUND;
-
if (--hctx->next_cpu_batch <= 0) {
int next_cpu;

--
2.13.5
\
 
 \ /
  Last update: 2017-08-21 15:51    [W:0.047 / U:0.408 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site