diff options
| author | Geert Uytterhoeven <geert+renesas@glider.be> | 2015-06-26 11:14:14 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-07-07 01:13:07 +0200 |
| commit | 93af5e93544328285a6f65f7d47bbea8979b28fb (patch) | |
| tree | 663bee85700a74fd773f2cf3a4860a0107af0160 | |
| parent | d770e558e21961ad6cfdf0ff7df0eb5d7d4f0754 (diff) | |
PM / Domains: Avoid infinite loops in attach/detach code
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>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/base/power/domain.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index cdd547bd67df..0ee43c1056e0 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -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(); } |