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Subject[PATCH 4/9] PM / Domains: Make pm_genpd_poweron() always survive parent removal
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

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>
---
drivers/base/power/domain.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

Index: linux-2.6/drivers/base/power/domain.c
===================================================================
--- linux-2.6.orig/drivers/base/power/domain.c
+++ linux-2.6/drivers/base/power/domain.c
@@ -89,12 +89,14 @@ static void genpd_set_active(struct gene
*/
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_d
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 */


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