driver core: Do not resume suppliers under device_links_write_lock() (5db25c9e) · Commits · 戴 / test

It is incorrect to call pm_runtime_get_sync() under device_links_write_lock(), because it may end up trying to take device_links_read_lock() while resuming the target device and that will deadlock in the non-SRCU case, so avoid that by resuming the supplier device in device_link_add() before calling device_links_write_lock(). Fixes: ("PM / runtime: Use device links") Fixes: ("PM / runtime: Optimize the use of device links") Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

+14 −6

Original line number	Diff line number	Diff line
		@@ -201,12 +201,21 @@ struct device_link device_link_add(struct device consumer,
		struct device *supplier, u32 flags)
		{
		struct device_link *link;
		bool rpm_put_supplier = false;

		if (!consumer \|\| !supplier \|\|
		(flags & DL_FLAG_STATELESS &&
		flags & (DL_FLAG_AUTOREMOVE_CONSUMER \| DL_FLAG_AUTOREMOVE_SUPPLIER)))
		return NULL;

		if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
		if (pm_runtime_get_sync(supplier) < 0) {
		pm_runtime_put_noidle(supplier);
		return NULL;
		}
		rpm_put_supplier = true;
		}

		device_links_write_lock();
		device_pm_lock();

		@@ -250,13 +259,8 @@ struct device_link device_link_add(struct device consumer,

		if (flags & DL_FLAG_PM_RUNTIME) {
		if (flags & DL_FLAG_RPM_ACTIVE) {
		if (pm_runtime_get_sync(supplier) < 0) {
		pm_runtime_put_noidle(supplier);
		kfree(link);
		link = NULL;
		goto out;
		}
		link->rpm_active = true;
		rpm_put_supplier = false;
		}
		pm_runtime_new_link(consumer);
		/*
		@@ -328,6 +332,10 @@ struct device_link device_link_add(struct device consumer,
		out:
		device_pm_unlock();
		device_links_write_unlock();

		if (rpm_put_supplier)
		pm_runtime_put(supplier);

		return link;
		}
		EXPORT_SYMBOL_GPL(device_link_add);

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