PM / Domains: Make pm_genpd_poweron() always survive parent removal

If pm_genpd_remove_subdomain() is called to remove a PM domain's
subdomain and pm_genpd_poweron() is called for that subdomain at
the same time, and the pm_genpd_poweron() called by it recursively
for the parent returns an error, the first pm_genpd_poweron()'s
error code path will attempt to decrement the subdomain counter of
a PM domain that it's not a subdomain of any more.

Rearrange the code in pm_genpd_poweron() to prevent this from
happening.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index ef25b6f..dc423a9 100644 (file)
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -89,12 +89,14 @@ static void genpd_set_active(struct generic_pm_domain *genpd)
  */
 int pm_genpd_poweron(struct generic_pm_domain *genpd)
 {
-       struct generic_pm_domain *parent = genpd->parent;
+       struct generic_pm_domain *parent;
        int ret = 0;
 
- start:
        mutex_lock(&genpd->lock);
 
+       parent = genpd->parent;
+
+ start:
        if (genpd->status == GPD_STATE_ACTIVE
            || (genpd->prepared_count > 0 && genpd->suspend_power_off))
                goto out;
@@ -110,29 +112,34 @@ int pm_genpd_poweron(struct generic_pm_domain *genpd)
                mutex_unlock(&genpd->lock);
 
                ret = pm_genpd_poweron(parent);
-               if (ret) {
-                       genpd_sd_counter_dec(parent);
-                       return ret;
-               }
+
+               mutex_lock(&genpd->lock);
+
+               if (ret)
+                       goto err;
 
                parent = NULL;
                goto start;
        }
 
-       if (genpd->power_on)
+       if (genpd->power_on) {
                ret = genpd->power_on(genpd);
-
-       if (ret) {
-               if (genpd->parent)
-                       genpd_sd_counter_dec(genpd->parent);
-       } else {
-               genpd_set_active(genpd);
+               if (ret)
+                       goto err;
        }
 
+       genpd_set_active(genpd);
+
  out:
        mutex_unlock(&genpd->lock);
 
        return ret;
+
+ err:
+       if (genpd->parent)
+               genpd_sd_counter_dec(genpd->parent);
+
+       goto out;
 }
 
 #endif /* CONFIG_PM */