@@ -6,6 +6,7 @@
* This file is released under the GPLv2.
*/
+#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/platform_device.h>
@@ -19,6 +20,8 @@
#include <linux/suspend.h>
#include <linux/export.h>
+#define GENPD_RETRY_MAX_MS 250 /* Approximate */
+
#define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \
({ \
type (*__routine)(struct device *__d); \
@@ -2131,6 +2134,7 @@ EXPORT_SYMBOL_GPL(of_genpd_get_from_provider);
static void genpd_dev_pm_detach(struct device *dev, bool power_off)
{
struct generic_pm_domain *pd;
+ unsigned int i;
int ret = 0;
pd = pm_genpd_lookup_dev(dev);
@@ -2139,10 +2143,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
dev_dbg(dev, "removing from PM domain %s\n", pd->name);
- while (1) {
+ for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
ret = pm_genpd_remove_device(pd, dev);
if (ret != -EAGAIN)
break;
+
+ mdelay(i);
cond_resched();
}
@@ -2183,6 +2189,7 @@ int genpd_dev_pm_attach(struct device *dev)
{
struct of_phandle_args pd_args;
struct generic_pm_domain *pd;
+ unsigned int i;
int ret;
if (!dev->of_node)
@@ -2218,10 +2225,12 @@ int genpd_dev_pm_attach(struct device *dev)
dev_dbg(dev, "adding to PM domain %s\n", pd->name);
- while (1) {
+ for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
ret = pm_genpd_add_device(pd, dev);
if (ret != -EAGAIN)
break;
+
+ mdelay(i);
cond_resched();
}
If pm_genpd_{add,remove}_device() keeps on failing with -EAGAIN, we end up with an infinite loop in genpd_dev_pm_{at,de}tach(). This may happen due to a genpd.prepared_count imbalance. This is a bug elsewhere, but it will result in a system lock up, possibly during reboot of an otherwise functioning system. To avoid this, put a limit on the maximum number of loop iterations, using an exponential back-off mechanism. If the limit is reached, the operation will just fail. An error message is already printed. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- v3: - Increase maximum timeout to ca. 250 ms (delay time only, i.e. not including actual processing time), - use mdelay() instead of udelay(), as the former is limited to 2 ms, - Use exponential back-off, busy waiting for 1 to 128 ms in each iteration, up to 255 ms in total, v2: - Add missing declaration of "i" in genpd_dev_pm_attach(). --- drivers/base/power/domain.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)