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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>
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1 changed files with 11 additions and 2 deletions
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@ -6,6 +6,7 @@
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* This file is released under the GPLv2.
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*/
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/io.h>
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#include <linux/platform_device.h>
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@ -19,6 +20,8 @@
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#include <linux/suspend.h>
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#include <linux/export.h>
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#define GENPD_RETRY_MAX_MS 250 /* Approximate */
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#define GENPD_DEV_CALLBACK(genpd, type, callback, dev) \
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({ \
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type (*__routine)(struct device *__d); \
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@ -2131,6 +2134,7 @@ EXPORT_SYMBOL_GPL(of_genpd_get_from_provider);
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static void genpd_dev_pm_detach(struct device *dev, bool power_off)
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{
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struct generic_pm_domain *pd;
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unsigned int i;
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int ret = 0;
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pd = pm_genpd_lookup_dev(dev);
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@ -2139,10 +2143,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off)
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dev_dbg(dev, "removing from PM domain %s\n", pd->name);
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while (1) {
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for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
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ret = pm_genpd_remove_device(pd, dev);
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if (ret != -EAGAIN)
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break;
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mdelay(i);
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cond_resched();
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}
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@ -2183,6 +2189,7 @@ int genpd_dev_pm_attach(struct device *dev)
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{
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struct of_phandle_args pd_args;
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struct generic_pm_domain *pd;
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unsigned int i;
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int ret;
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if (!dev->of_node)
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@ -2218,10 +2225,12 @@ int genpd_dev_pm_attach(struct device *dev)
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dev_dbg(dev, "adding to PM domain %s\n", pd->name);
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while (1) {
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for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
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ret = pm_genpd_add_device(pd, dev);
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if (ret != -EAGAIN)
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break;
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mdelay(i);
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cond_resched();
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}
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