From eb4400e3a040b90a3ad805b01fcbc99a5f615c8f Mon Sep 17 00:00:00 2001 From: Maciej Sosnowski Date: Mon, 2 Feb 2009 23:26:57 -0800 Subject: [PATCH] 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: Maciej Sosnowski Acked-by: Jeff Kirsher Signed-off-by: David S. Miller --- drivers/dca/dca-core.c | 51 +++++++++++++++++++++++++++--------------- 1 file changed, 33 insertions(+), 18 deletions(-) diff --git a/drivers/dca/dca-core.c b/drivers/dca/dca-core.c index 55433849bfa6..33bd75347518 100644 --- a/drivers/dca/dca-core.c +++ b/drivers/dca/dca-core.c @@ -28,7 +28,7 @@ #include #include -#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) { - dca->ops->remove_requester(dca, dev); - spin_unlock(&dca_lock); + spin_lock_irqsave(&dca_lock, flags); + if (dca == dca_find_provider_by_dev(dev)) + dca->ops->remove_requester(dca, dev); + 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);