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Commit eb4400e3 authored by Maciej Sosnowski's avatar Maciej Sosnowski Committed by David S. Miller
Browse files

dca: redesign locks to fix deadlocks 



Change spin_locks to irqsave to prevent dead-locks.
Protect adding and deleting to/from dca_providers list.
Drop the lock during dca_sysfs_add_req() and dca_sysfs_remove_req() calls
as they might sleep (use GFP_KERNEL allocation).

Signed-off-by: default avatarMaciej Sosnowski <maciej.sosnowski@intel.com>
Acked-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff01b916

drivers/dca/dca-core.c

+33 −18
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ 
#include <linux/device.h>

#include <linux/dca.h>



#define DCA_VERSION "1.4"

#define DCA_VERSION "1.8"



MODULE_VERSION(DCA_VERSION);

MODULE_LICENSE("GPL");
@@ -60,16 +60,17 @@ int dca_add_requester(struct device *dev) 
{

	struct dca_provider *dca;

	int err, slot = -ENODEV;

	unsigned long flags;



	if (!dev)

		return -EFAULT;



	spin_lock(&dca_lock);

	spin_lock_irqsave(&dca_lock, flags);



	/* check if the requester has not been added already */

	dca = dca_find_provider_by_dev(dev);

	if (dca) {

		spin_unlock(&dca_lock);

		spin_unlock_irqrestore(&dca_lock, flags);

		return -EEXIST;

	}
@@ -78,19 +79,21 @@ int dca_add_requester(struct device *dev) 
		if (slot >= 0)

			break;

	}

	if (slot < 0) {

		spin_unlock(&dca_lock);



	spin_unlock_irqrestore(&dca_lock, flags);



	if (slot < 0)

		return slot;

	}



	err = dca_sysfs_add_req(dca, dev, slot);

	if (err) {

		spin_lock_irqsave(&dca_lock, flags);

		if (dca == dca_find_provider_by_dev(dev))

			dca->ops->remove_requester(dca, dev);

		spin_unlock(&dca_lock);

		spin_unlock_irqrestore(&dca_lock, flags);

		return err;

	}



	spin_unlock(&dca_lock);

	return 0;

}

EXPORT_SYMBOL_GPL(dca_add_requester);
@@ -103,25 +106,25 @@ int dca_remove_requester(struct device *dev) 
{

	struct dca_provider *dca;

	int slot;

	unsigned long flags;



	if (!dev)

		return -EFAULT;



	spin_lock(&dca_lock);

	spin_lock_irqsave(&dca_lock, flags);

	dca = dca_find_provider_by_dev(dev);

	if (!dca) {

		spin_unlock(&dca_lock);

		spin_unlock_irqrestore(&dca_lock, flags);

		return -ENODEV;

	}

	slot = dca->ops->remove_requester(dca, dev);

	if (slot < 0) {

		spin_unlock(&dca_lock);

	spin_unlock_irqrestore(&dca_lock, flags);



	if (slot < 0)

		return slot;

	}



	dca_sysfs_remove_req(dca, slot);



	spin_unlock(&dca_lock);

	return 0;

}

EXPORT_SYMBOL_GPL(dca_remove_requester);
@@ -135,17 +138,18 @@ u8 dca_common_get_tag(struct device *dev, int cpu) 
{

	struct dca_provider *dca;

	u8 tag;

	unsigned long flags;



	spin_lock(&dca_lock);

	spin_lock_irqsave(&dca_lock, flags);



	dca = dca_find_provider_by_dev(dev);

	if (!dca) {

		spin_unlock(&dca_lock);

		spin_unlock_irqrestore(&dca_lock, flags);

		return -ENODEV;

	}

	tag = dca->ops->get_tag(dca, dev, cpu);



	spin_unlock(&dca_lock);

	spin_unlock_irqrestore(&dca_lock, flags);

	return tag;

}
@@ -217,11 +221,16 @@ static BLOCKING_NOTIFIER_HEAD(dca_provider_chain); 
int register_dca_provider(struct dca_provider *dca, struct device *dev)

{

	int err;

	unsigned long flags;



	err = dca_sysfs_add_provider(dca, dev);

	if (err)

		return err;



	spin_lock_irqsave(&dca_lock, flags);

	list_add(&dca->node, &dca_providers);

	spin_unlock_irqrestore(&dca_lock, flags);



	blocking_notifier_call_chain(&dca_provider_chain,

				     DCA_PROVIDER_ADD, NULL);

	return 0;
@@ -234,9 +243,15 @@ EXPORT_SYMBOL_GPL(register_dca_provider); 
 */

void unregister_dca_provider(struct dca_provider *dca)

{

	unsigned long flags;



	blocking_notifier_call_chain(&dca_provider_chain,

				     DCA_PROVIDER_REMOVE, NULL);



	spin_lock_irqsave(&dca_lock, flags);

	list_del(&dca->node);

	spin_unlock_irqrestore(&dca_lock, flags);



	dca_sysfs_remove_provider(dca);

}

EXPORT_SYMBOL_GPL(unregister_dca_provider);