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authorMarek Szyprowski <m.szyprowski@samsung.com>2016-01-20 10:13:42 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-01-22 02:31:32 +0100
commit0106ef5146f9e89e4dc9354f308ecaddb9617310 (patch)
tree1f47d684e99234ecc779ddc1bb1ae87beb77b168 /drivers/base
parente219aafe50fd546b8686582ddbafd24c3c2eda04 (diff)
downloadlinux-0106ef5146f9e89e4dc9354f308ecaddb9617310.tar.bz2
PM / domains: fix lockdep issue for all subdomains
During genpd_poweron, genpd->lock is acquired recursively for each parent (master) domain, which are separate objects. This confuses lockdep, which considers every operation on genpd->lock as being done on the same lock class. This leads to the following false positive warning: ============================================= [ INFO: possible recursive locking detected ] 4.4.0-rc4-xu3s #32 Not tainted --------------------------------------------- swapper/0/1 is trying to acquire lock: (&genpd->lock){+.+...}, at: [<c0361550>] __genpd_poweron+0x64/0x108 but task is already holding lock: (&genpd->lock){+.+...}, at: [<c0361af8>] genpd_dev_pm_attach+0x168/0x1b8 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&genpd->lock); lock(&genpd->lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by swapper/0/1: #0: (&dev->mutex){......}, at: [<c0350910>] __driver_attach+0x48/0x98 #1: (&dev->mutex){......}, at: [<c0350920>] __driver_attach+0x58/0x98 #2: (&genpd->lock){+.+...}, at: [<c0361af8>] genpd_dev_pm_attach+0x168/0x1b8 stack backtrace: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-rc4-xu3s #32 Hardware name: SAMSUNG EXYNOS (Flattened Device Tree) [<c0016c98>] (unwind_backtrace) from [<c00139c4>] (show_stack+0x10/0x14) [<c00139c4>] (show_stack) from [<c0270df0>] (dump_stack+0x84/0xc4) [<c0270df0>] (dump_stack) from [<c00780b8>] (__lock_acquire+0x1f88/0x215c) [<c00780b8>] (__lock_acquire) from [<c007886c>] (lock_acquire+0xa4/0xd0) [<c007886c>] (lock_acquire) from [<c0641f2c>] (mutex_lock_nested+0x70/0x4d4) [<c0641f2c>] (mutex_lock_nested) from [<c0361550>] (__genpd_poweron+0x64/0x108) [<c0361550>] (__genpd_poweron) from [<c0361b00>] (genpd_dev_pm_attach+0x170/0x1b8) [<c0361b00>] (genpd_dev_pm_attach) from [<c03520a8>] (platform_drv_probe+0x2c/0xac) [<c03520a8>] (platform_drv_probe) from [<c03507d4>] (driver_probe_device+0x208/0x2fc) [<c03507d4>] (driver_probe_device) from [<c035095c>] (__driver_attach+0x94/0x98) [<c035095c>] (__driver_attach) from [<c034ec14>] (bus_for_each_dev+0x68/0x9c) [<c034ec14>] (bus_for_each_dev) from [<c034fec8>] (bus_add_driver+0x1a0/0x218) [<c034fec8>] (bus_add_driver) from [<c035115c>] (driver_register+0x78/0xf8) [<c035115c>] (driver_register) from [<c0338488>] (exynos_drm_register_drivers+0x28/0x74) [<c0338488>] (exynos_drm_register_drivers) from [<c0338594>] (exynos_drm_init+0x6c/0xc4) [<c0338594>] (exynos_drm_init) from [<c00097f4>] (do_one_initcall+0x90/0x1dc) [<c00097f4>] (do_one_initcall) from [<c0895e08>] (kernel_init_freeable+0x158/0x1f8) [<c0895e08>] (kernel_init_freeable) from [<c063ecac>] (kernel_init+0x8/0xe8) [<c063ecac>] (kernel_init) from [<c000f7d0>] (ret_from_fork+0x14/0x24) This patch replaces mutex_lock with mutex_lock_nested() and uses recursion depth to annotate each genpd->lock operation with separate lockdep subclass. Reported-by: Anand Moon <linux.amoon@gmail.com> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Tested-by: Anand Moon <linux.amoon@gmail.com> Tested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de> Acked-by: Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/power/domain.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index b80379012840..e02ddf65bc43 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -170,16 +170,15 @@ static void genpd_queue_power_off_work(struct generic_pm_domain *genpd)
queue_work(pm_wq, &genpd->power_off_work);
}
-static int genpd_poweron(struct generic_pm_domain *genpd);
-
/**
* __genpd_poweron - Restore power to a given PM domain and its masters.
* @genpd: PM domain to power up.
+ * @depth: nesting count for lockdep.
*
* Restore power to @genpd and all of its masters so that it is possible to
* resume a device belonging to it.
*/
-static int __genpd_poweron(struct generic_pm_domain *genpd)
+static int __genpd_poweron(struct generic_pm_domain *genpd, unsigned int depth)
{
struct gpd_link *link;
int ret = 0;
@@ -194,11 +193,16 @@ static int __genpd_poweron(struct generic_pm_domain *genpd)
* with it.
*/
list_for_each_entry(link, &genpd->slave_links, slave_node) {
- genpd_sd_counter_inc(link->master);
+ struct generic_pm_domain *master = link->master;
+
+ genpd_sd_counter_inc(master);
+
+ mutex_lock_nested(&master->lock, depth + 1);
+ ret = __genpd_poweron(master, depth + 1);
+ mutex_unlock(&master->lock);
- ret = genpd_poweron(link->master);
if (ret) {
- genpd_sd_counter_dec(link->master);
+ genpd_sd_counter_dec(master);
goto err;
}
}
@@ -230,11 +234,12 @@ static int genpd_poweron(struct generic_pm_domain *genpd)
int ret;
mutex_lock(&genpd->lock);
- ret = __genpd_poweron(genpd);
+ ret = __genpd_poweron(genpd, 0);
mutex_unlock(&genpd->lock);
return ret;
}
+
static int genpd_save_dev(struct generic_pm_domain *genpd, struct device *dev)
{
return GENPD_DEV_CALLBACK(genpd, int, save_state, dev);
@@ -482,7 +487,7 @@ static int pm_genpd_runtime_resume(struct device *dev)
}
mutex_lock(&genpd->lock);
- ret = __genpd_poweron(genpd);
+ ret = __genpd_poweron(genpd, 0);
mutex_unlock(&genpd->lock);
if (ret)