diff options
| author |   Ulf Hansson <ulf.hansson@linaro.org> | 2016-01-27 09:10:37 +0100 |
|---|---|---|
| committer |   Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-01-27 23:01:25 +0100 |
| commit | cdb300a041f5df1dfbde1367f95109b6449d1371 (patch) | |
| tree | d4432a4fedc2b1938268531044856f34f1b87f0a /drivers | |
| parent | PM / domains: fix lockdep issue for all subdomains (diff) | |
| download | linux-dev-cdb300a041f5df1dfbde1367f95109b6449d1371.tar.xz linux-dev-cdb300a041f5df1dfbde1367f95109b6449d1371.zip | |
PM / Domains: Fix potential deadlock while adding/removing subdomains
We must preserve the same order of how we acquire and release the lock for
genpd, as otherwise we may encounter deadlocks.
The power on phase of a genpd starts by acquiring its lock. Then it walks
the hierarchy of its parent domains to be able to power on these first, as
per design of genpd.
From a locking perspective this means the locks of the parents becomes
acquired after the lock of the subdomain.
Let's fix pm_genpd_add|remove_subdomain() to maintain the same order of
acquiring/releasing the genpd lock as being applied in the power on/off
sequence.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/base/power/domain.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index e02ddf65bc43..2ff818c2ae6b 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1340,8 +1340,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd, if (!link) return -ENOMEM; - mutex_lock(&genpd->lock); - mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING); + mutex_lock(&subdomain->lock); + mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING); if (genpd->status == GPD_STATE_POWER_OFF && subdomain->status != GPD_STATE_POWER_OFF) { @@ -1364,8 +1364,8 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd, genpd_sd_counter_inc(genpd); out: - mutex_unlock(&subdomain->lock); mutex_unlock(&genpd->lock); + mutex_unlock(&subdomain->lock); if (ret) kfree(link); return ret; @@ -1386,7 +1386,8 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd, if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain)) return -EINVAL; - mutex_lock(&genpd->lock); + mutex_lock(&subdomain->lock); + mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING); if (!list_empty(&subdomain->slave_links) || subdomain->device_count) { pr_warn("%s: unable to remove subdomain %s\n", genpd->name, @@ -1399,22 +1400,19 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd, if (link->slave != subdomain) continue; - mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING); - list_del(&link->master_node); list_del(&link->slave_node); kfree(link); if (subdomain->status != GPD_STATE_POWER_OFF) genpd_sd_counter_dec(genpd); - mutex_unlock(&subdomain->lock); - ret = 0; break; } out: mutex_unlock(&genpd->lock); + mutex_unlock(&subdomain->lock); return ret; } |