lkml.org 
[lkml]   [2019]   [Mar]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 4.19 39/52] PM / Domains: Avoid a potential deadlock
Date
From: Jiada Wang <jiada_wang@mentor.com>

[ Upstream commit 2071ac985d37efe496782c34318dbead93beb02f ]

Lockdep warns that prepare_lock and genpd->mlock can cause a deadlock
the deadlock scenario is like following:
First thread is probing cs2000
cs2000_probe()
clk_register()
__clk_core_init()
clk_prepare_lock() ----> acquires prepare_lock
cs2000_recalc_rate()
i2c_smbus_read_byte_data()
rcar_i2c_master_xfer()
dma_request_chan()
rcar_dmac_of_xlate()
rcar_dmac_alloc_chan_resources()
pm_runtime_get_sync()
__pm_runtime_resume()
rpm_resume()
rpm_callback()
genpd_runtime_resume() ----> acquires genpd->mlock

Second thread is attaching any device to the same PM domain
genpd_add_device()
genpd_lock() ----> acquires genpd->mlock
cpg_mssr_attach_dev()
of_clk_get_from_provider()
__of_clk_get_from_provider()
__clk_create_clk()
clk_prepare_lock() ----> acquires prepare_lock

Since currently no PM provider access genpd's critical section
in .attach_dev, and .detach_dev callbacks, so there is no need to protect
these two callbacks with genpd->mlock.
This patch avoids a potential deadlock by moving out .attach_dev and .detach_dev
from genpd->mlock, so that genpd->mlock won't be held when prepare_lock is acquired
in .attach_dev and .detach_dev

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/base/power/domain.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 4b5714199490..bf5be0bfaf77 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -1388,12 +1388,12 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
if (IS_ERR(gpd_data))
return PTR_ERR(gpd_data);

- genpd_lock(genpd);
-
ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
if (ret)
goto out;

+ genpd_lock(genpd);
+
dev_pm_domain_set(dev, &genpd->domain);

genpd->device_count++;
@@ -1401,9 +1401,8 @@ static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,

list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);

- out:
genpd_unlock(genpd);
-
+ out:
if (ret)
genpd_free_dev_data(dev, gpd_data);
else
@@ -1452,15 +1451,15 @@ static int genpd_remove_device(struct generic_pm_domain *genpd,
genpd->device_count--;
genpd->max_off_time_changed = true;

- if (genpd->detach_dev)
- genpd->detach_dev(genpd, dev);
-
dev_pm_domain_set(dev, NULL);

list_del_init(&pdd->list_node);

genpd_unlock(genpd);

+ if (genpd->detach_dev)
+ genpd->detach_dev(genpd, dev);
+
genpd_free_dev_data(dev, gpd_data);

return 0;
--
2.19.1
\
 
 \ /
  Last update: 2019-03-30 02:06    [W:0.123 / U:0.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site