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 500de1dee967..a00ca6b8117b 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1467,12 +1467,12 @@ 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++; @@ -1480,9 +1480,8 @@ 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 @@ -1531,15 +1530,15 @@ 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;