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| author |   Jiada Wang <jiada_wang@mentor.com> | 2019-03-12 15:51:28 +0900 |
|---|---|---|
| committer |   Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2019-03-19 22:58:04 +0100 |
| commit | 2071ac985d37efe496782c34318dbead93beb02f (patch) | |
| tree | 3c972dc36f2bd040c35e04387972b4a43d6abf94 /drivers/base/power | |
| parent | Linux 5.1-rc1 (diff) | |
| download | linux-dev-2071ac985d37efe496782c34318dbead93beb02f.tar.xz linux-dev-2071ac985d37efe496782c34318dbead93beb02f.zip | |
PM / Domains: Avoid a potential deadlock
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>
Diffstat (limited to 'drivers/base/power')
| -rw-r--r-- | drivers/base/power/domain.c | 13 |
1 files changed, 6 insertions, 7 deletions
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 76c9969b7124..96a6dc9d305c 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1469,12 +1469,12 @@ 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++; @@ -1482,9 +1482,8 @@ 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 @@ -1533,15 +1532,15 @@ 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; |