aboutsummaryrefslogtreecommitdiff
path: root/drivers/hwspinlock
diff options
context:
space:
mode:
authorJuan Gutierrez <jgutierrez@ti.com>2011-09-06 09:30:16 +0300
committerOhad Ben-Cohen <ohad@wizery.com>2011-09-21 19:45:32 +0300
commit93b465c2e186d96fb90012ba0f9372eb9952e732 (patch)
tree3781c5443068f2fc79c2bb70c8793075b608d1f0 /drivers/hwspinlock
parentc3c1250e93a7ab1327a9fc49d2a22405672f4204 (diff)
downloadlinux-93b465c2e186d96fb90012ba0f9372eb9952e732.tar.gz
hwspinlock/core: use a mutex to protect the radix tree
Since we're using non-atomic radix tree allocations, we should be protecting the tree using a mutex and not a spinlock. Non-atomic allocations and process context locking is good enough, as the tree is manipulated only when locks are registered/ unregistered/requested/freed. The locks themselves are still protected by spinlocks of course, and mutexes are not involved in the locking/unlocking paths. Cc: <stable@kernel.org> Signed-off-by: Juan Gutierrez <jgutierrez@ti.com> [ohad@wizery.com: rewrite the commit log, #include mutex.h, add minor commentary] [ohad@wizery.com: update register/unregister parts in hwspinlock.txt] Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Diffstat (limited to 'drivers/hwspinlock')
-rw-r--r--drivers/hwspinlock/hwspinlock_core.c45
1 files changed, 20 insertions, 25 deletions
diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c
index 4eb85b4a320..0d20b82df0a 100644
--- a/drivers/hwspinlock/hwspinlock_core.c
+++ b/drivers/hwspinlock/hwspinlock_core.c
@@ -26,6 +26,7 @@
#include <linux/radix-tree.h>
#include <linux/hwspinlock.h>
#include <linux/pm_runtime.h>
+#include <linux/mutex.h>
#include "hwspinlock_internal.h"
@@ -52,10 +53,12 @@
static RADIX_TREE(hwspinlock_tree, GFP_KERNEL);
/*
- * Synchronization of access to the tree is achieved using this spinlock,
+ * Synchronization of access to the tree is achieved using this mutex,
* as the radix-tree API requires that users provide all synchronisation.
+ * A mutex is needed because we're using non-atomic radix tree allocations.
*/
-static DEFINE_SPINLOCK(hwspinlock_tree_lock);
+static DEFINE_MUTEX(hwspinlock_tree_lock);
+
/**
* __hwspin_trylock() - attempt to lock a specific hwspinlock
@@ -261,8 +264,7 @@ EXPORT_SYMBOL_GPL(__hwspin_unlock);
* This function should be called from the underlying platform-specific
* implementation, to register a new hwspinlock instance.
*
- * Can be called from an atomic context (will not sleep) but not from
- * within interrupt context.
+ * Should be called from a process context (might sleep)
*
* Returns 0 on success, or an appropriate error code on failure
*/
@@ -279,7 +281,7 @@ int hwspin_lock_register(struct hwspinlock *hwlock)
spin_lock_init(&hwlock->lock);
- spin_lock(&hwspinlock_tree_lock);
+ mutex_lock(&hwspinlock_tree_lock);
ret = radix_tree_insert(&hwspinlock_tree, hwlock->id, hwlock);
if (ret == -EEXIST)
@@ -295,7 +297,7 @@ int hwspin_lock_register(struct hwspinlock *hwlock)
WARN_ON(tmp != hwlock);
out:
- spin_unlock(&hwspinlock_tree_lock);
+ mutex_unlock(&hwspinlock_tree_lock);
return ret;
}
EXPORT_SYMBOL_GPL(hwspin_lock_register);
@@ -307,8 +309,7 @@ EXPORT_SYMBOL_GPL(hwspin_lock_register);
* This function should be called from the underlying platform-specific
* implementation, to unregister an existing (and unused) hwspinlock.
*
- * Can be called from an atomic context (will not sleep) but not from
- * within interrupt context.
+ * Should be called from a process context (might sleep)
*
* Returns the address of hwspinlock @id on success, or NULL on failure
*/
@@ -317,7 +318,7 @@ struct hwspinlock *hwspin_lock_unregister(unsigned int id)
struct hwspinlock *hwlock = NULL;
int ret;
- spin_lock(&hwspinlock_tree_lock);
+ mutex_lock(&hwspinlock_tree_lock);
/* make sure the hwspinlock is not in use (tag is set) */
ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED);
@@ -333,7 +334,7 @@ struct hwspinlock *hwspin_lock_unregister(unsigned int id)
}
out:
- spin_unlock(&hwspinlock_tree_lock);
+ mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
EXPORT_SYMBOL_GPL(hwspin_lock_unregister);
@@ -402,9 +403,7 @@ EXPORT_SYMBOL_GPL(hwspin_lock_get_id);
* to the remote core before it can be used for synchronization (to get the
* id of a given hwlock, use hwspin_lock_get_id()).
*
- * Can be called from an atomic context (will not sleep) but not from
- * within interrupt context (simply because there is no use case for
- * that yet).
+ * Should be called from a process context (might sleep)
*
* Returns the address of the assigned hwspinlock, or NULL on error
*/
@@ -413,7 +412,7 @@ struct hwspinlock *hwspin_lock_request(void)
struct hwspinlock *hwlock;
int ret;
- spin_lock(&hwspinlock_tree_lock);
+ mutex_lock(&hwspinlock_tree_lock);
/* look for an unused lock */
ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock,
@@ -433,7 +432,7 @@ struct hwspinlock *hwspin_lock_request(void)
hwlock = NULL;
out:
- spin_unlock(&hwspinlock_tree_lock);
+ mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
EXPORT_SYMBOL_GPL(hwspin_lock_request);
@@ -447,9 +446,7 @@ EXPORT_SYMBOL_GPL(hwspin_lock_request);
* Usually early board code will be calling this function in order to
* reserve specific hwspinlock ids for predefined purposes.
*
- * Can be called from an atomic context (will not sleep) but not from
- * within interrupt context (simply because there is no use case for
- * that yet).
+ * Should be called from a process context (might sleep)
*
* Returns the address of the assigned hwspinlock, or NULL on error
*/
@@ -458,7 +455,7 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
struct hwspinlock *hwlock;
int ret;
- spin_lock(&hwspinlock_tree_lock);
+ mutex_lock(&hwspinlock_tree_lock);
/* make sure this hwspinlock exists */
hwlock = radix_tree_lookup(&hwspinlock_tree, id);
@@ -484,7 +481,7 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id)
hwlock = NULL;
out:
- spin_unlock(&hwspinlock_tree_lock);
+ mutex_unlock(&hwspinlock_tree_lock);
return hwlock;
}
EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
@@ -497,9 +494,7 @@ EXPORT_SYMBOL_GPL(hwspin_lock_request_specific);
* Should only be called with an @hwlock that was retrieved from
* an earlier call to omap_hwspin_lock_request{_specific}.
*
- * Can be called from an atomic context (will not sleep) but not from
- * within interrupt context (simply because there is no use case for
- * that yet).
+ * Should be called from a process context (might sleep)
*
* Returns 0 on success, or an appropriate error code on failure
*/
@@ -513,7 +508,7 @@ int hwspin_lock_free(struct hwspinlock *hwlock)
return -EINVAL;
}
- spin_lock(&hwspinlock_tree_lock);
+ mutex_lock(&hwspinlock_tree_lock);
/* make sure the hwspinlock is used */
ret = radix_tree_tag_get(&hwspinlock_tree, hwlock->id,
@@ -540,7 +535,7 @@ int hwspin_lock_free(struct hwspinlock *hwlock)
module_put(hwlock->dev->driver->owner);
out:
- spin_unlock(&hwspinlock_tree_lock);
+ mutex_unlock(&hwspinlock_tree_lock);
return ret;
}
EXPORT_SYMBOL_GPL(hwspin_lock_free);