[PATCH 4.18 141/350] scsi: ufs: Schedule clk gating work on correct queue

Greg Kroah-Hartman
2018-11-11T23:33:14Z

From: Evan Green <evgreen@chromium.org>

[ Upstream commit f4bb7704699beee9edfbee875daa9089c86cf724 ]

With commit 10e5e37581fc ("scsi: ufs: Add clock ungating to a separate
workqueue"), clock gating work was moved to a separate work queue with
WQ_MEM_RECLAIM set, since clock gating could occur from a memory reclaim
context. Unfortunately, clk_gating.gate_work was left queued via
schedule_delayed_work, which is a system workqueue that does not have
WQ_MEM_RECLAIM set. Because ufshcd_ungate_work attempts to cancel
gate_work, the following warning appears:

[ 14.174170] workqueue: WQ_MEM_RECLAIM ufs_clk_gating_0:ufshcd_ungate_work is flushing !WQ_MEM_RECLAIM events:ufshcd_gate_work
[ 14.174179] WARNING: CPU: 4 PID: 173 at kernel/workqueue.c:2440 check_flush_dependency+0x110/0x118
[ 14.205725] CPU: 4 PID: 173 Comm: kworker/u16:3 Not tainted 4.14.68 #1
[ 14.212437] Hardware name: Google Cheza (rev1) (DT)
[ 14.217459] Workqueue: ufs_clk_gating_0 ufshcd_ungate_work
[ 14.223107] task: ffffffc0f6a40080 task.stack: ffffff800a490000
[ 14.229195] PC is at check_flush_dependency+0x110/0x118
[ 14.234569] LR is at check_flush_dependency+0x110/0x118
[ 14.239944] pc : [<ffffff80080cad14>] lr : [<ffffff80080cad14>] pstate: 60c001c9
[ 14.333050] Call trace:
[ 14.427767] [<ffffff80080cad14>] check_flush_dependency+0x110/0x118
[ 14.434219] [<ffffff80080cafec>] start_flush_work+0xac/0x1fc
[ 14.440046] [<ffffff80080caeec>] flush_work+0x40/0x94
[ 14.445246] [<ffffff80080cb288>] __cancel_work_timer+0x11c/0x1b8
[ 14.451433] [<ffffff80080cb4b8>] cancel_delayed_work_sync+0x20/0x30
[ 14.457886] [<ffffff80085b9294>] ufshcd_ungate_work+0x24/0xd0
[ 14.463800] [<ffffff80080cfb04>] process_one_work+0x32c/0x690
[ 14.469713] [<ffffff80080d0154>] worker_thread+0x218/0x338
[ 14.475361] [<ffffff80080d527c>] kthread+0x120/0x130
[ 14.480470] [<ffffff8008084814>] ret_from_fork+0x10/0x18

The simple solution is to put the gate_work on the same WQ_MEM_RECLAIM
work queue as the ungate_work.

Fixes: 10e5e37581fc ("scsi: ufs: Add clock ungating to a separate workqueue")
Signed-off-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/scsi/ufs/ufshcd.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -1677,8 +1677,9 @@ static void __ufshcd_release(struct ufs_

hba->clk_gating.state = REQ_CLKS_OFF;
trace_ufshcd_clk_gating(dev_name(hba->dev), hba->clk_gating.state);
- schedule_delayed_work(&hba->clk_gating.gate_work,
- msecs_to_jiffies(hba->clk_gating.delay_ms));
+ queue_delayed_work(hba->clk_gating.clk_gating_workq,
+ &hba->clk_gating.gate_work,
+ msecs_to_jiffies(hba->clk_gating.delay_ms));
}

void ufshcd_release(struct ufs_hba *hba)