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>

1 files changed, 20 insertions, 13 deletions

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index ef25b6f99f99..dc423a99c67c 100644
--- 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 */