From: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> I had to mess with the locking a bit as I converted the code from a mutex to the xa_lock. Signed-off-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> --- drivers/hwspinlock/hwspinlock_core.c | 151 ++++++++++++----------------------- 1 file changed, 52 insertions(+), 99 deletions(-) diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c index 4074441444fe..acb6e315925f 100644 --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -23,43 +23,32 @@ #include <linux/types.h> #include <linux/err.h> #include <linux/jiffies.h> -#include <linux/radix-tree.h> +#include <linux/xarray.h> #include <linux/hwspinlock.h> #include <linux/pm_runtime.h> -#include <linux/mutex.h> #include <linux/of.h> #include "hwspinlock_internal.h" -/* radix tree tags */ -#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */ +#define HWSPINLOCK_UNUSED XA_TAG_0 /* - * A radix tree is used to maintain the available hwspinlock instances. - * The tree associates hwspinlock pointers with their integer key id, + * An xarray is used to maintain the available hwspinlock instances. + * The array associates hwspinlock pointers with their integer key id, * and provides easy-to-use API which makes the hwspinlock core code simple * and easy to read. * - * Radix trees are quick on lookups, and reasonably efficient in terms of + * The XArray is quick on lookups, and reasonably efficient in terms of * storage, especially with high density usages such as this framework * requires (a continuous range of integer keys, beginning with zero, is * used as the ID's of the hwspinlock instances). * - * The radix tree API supports tagging items in the tree, which this - * framework uses to mark unused hwspinlock instances (see the - * HWSPINLOCK_UNUSED tag above). As a result, the process of querying the - * tree, looking for an unused hwspinlock instance, is now reduced to a - * single radix tree API call. + * The xarray API supports tagging items, which this framework uses to mark + * unused hwspinlock instances (see the HWSPINLOCK_UNUSED tag above). As a + * result, the process of querying the array, looking for an unused + * hwspinlock instance, is reduced to a single call. */ -static RADIX_TREE(hwspinlock_tree, GFP_KERNEL); - -/* - * 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_MUTEX(hwspinlock_tree_lock); - +static DEFINE_XARRAY(hwspinlock_xa); /** * __hwspin_trylock() - attempt to lock a specific hwspinlock @@ -294,10 +283,9 @@ of_hwspin_lock_simple_xlate(const struct of_phandle_args *hwlock_spec) */ int of_hwspin_lock_get_id(struct device_node *np, int index) { + XA_STATE(xas, &hwspinlock_xa, 0); struct of_phandle_args args; struct hwspinlock *hwlock; - struct radix_tree_iter iter; - void **slot; int id; int ret; @@ -309,22 +297,15 @@ int of_hwspin_lock_get_id(struct device_node *np, int index) /* Find the hwspinlock device: we need its base_id */ ret = -EPROBE_DEFER; rcu_read_lock(); - radix_tree_for_each_slot(slot, &hwspinlock_tree, &iter, 0) { - hwlock = radix_tree_deref_slot(slot); - if (unlikely(!hwlock)) - continue; - if (radix_tree_deref_retry(hwlock)) { - slot = radix_tree_iter_retry(&iter); + xas_for_each(&xas, hwlock, ULONG_MAX) { + if (xas_retry(&xas, hwlock)) continue; - } - if (hwlock->bank->dev->of_node == args.np) { - ret = 0; + if (hwlock->bank->dev->of_node == args.np) break; - } } rcu_read_unlock(); - if (ret < 0) + if (!hwlock) goto out; id = of_hwspin_lock_simple_xlate(&args); @@ -332,6 +313,7 @@ int of_hwspin_lock_get_id(struct device_node *np, int index) ret = -EINVAL; goto out; } + ret = 0; id += hwlock->bank->base_id; out: @@ -342,26 +324,19 @@ EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id); static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id) { - struct hwspinlock *tmp; - int ret; + void *curr; - mutex_lock(&hwspinlock_tree_lock); - - ret = radix_tree_insert(&hwspinlock_tree, id, hwlock); - if (ret) { - if (ret == -EEXIST) + curr = xa_cmpxchg(&hwspinlock_xa, id, NULL, hwlock, GFP_KERNEL); + if (curr) { + if (!xa_is_err(curr)) pr_err("hwspinlock id %d already exists!\n", id); goto out; } /* mark this hwspinlock as available */ - tmp = radix_tree_tag_set(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); - - /* self-sanity check which should never fail */ - WARN_ON(tmp != hwlock); + xa_set_tag(&hwspinlock_xa, id, HWSPINLOCK_UNUSED); out: - mutex_unlock(&hwspinlock_tree_lock); return 0; } @@ -370,23 +345,16 @@ static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id) struct hwspinlock *hwlock = NULL; int ret; - 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); + ret = xa_get_tag(&hwspinlock_xa, id, HWSPINLOCK_UNUSED); if (ret == 0) { pr_err("hwspinlock %d still in use (or not present)\n", id); goto out; } - hwlock = radix_tree_delete(&hwspinlock_tree, id); - if (!hwlock) { - pr_err("failed to delete hwspinlock %d\n", id); - goto out; - } + hwlock = xa_erase(&hwspinlock_xa, id); out: - mutex_unlock(&hwspinlock_tree_lock); return hwlock; } @@ -477,8 +445,7 @@ EXPORT_SYMBOL_GPL(hwspin_lock_unregister); * __hwspin_lock_request() - tag an hwspinlock as used and power it up * * This is an internal function that prepares an hwspinlock instance - * before it is given to the user. The function assumes that - * hwspinlock_tree_lock is taken. + * before it is given to the user. * * Returns 0 or positive to indicate success, and a negative value to * indicate an error (with the appropriate error code) @@ -486,7 +453,6 @@ EXPORT_SYMBOL_GPL(hwspin_lock_unregister); static int __hwspin_lock_request(struct hwspinlock *hwlock) { struct device *dev = hwlock->bank->dev; - struct hwspinlock *tmp; int ret; /* prevent underlying implementation from being removed */ @@ -501,16 +467,7 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock) dev_err(dev, "%s: can't power on device\n", __func__); pm_runtime_put_noidle(dev); module_put(dev->driver->owner); - return ret; } - - /* mark hwspinlock as used, should not fail */ - tmp = radix_tree_tag_clear(&hwspinlock_tree, hwlock_to_id(hwlock), - HWSPINLOCK_UNUSED); - - /* self-sanity check that should never fail */ - WARN_ON(tmp != hwlock); - return ret; } @@ -548,29 +505,28 @@ struct hwspinlock *hwspin_lock_request(void) { struct hwspinlock *hwlock; int ret; + unsigned long index = 0; - mutex_lock(&hwspinlock_tree_lock); + xa_lock(&hwspinlock_xa); /* look for an unused lock */ - ret = radix_tree_gang_lookup_tag(&hwspinlock_tree, (void **)&hwlock, - 0, 1, HWSPINLOCK_UNUSED); - if (ret == 0) { + hwlock = xa_find(&hwspinlock_xa, &index, ULONG_MAX, HWSPINLOCK_UNUSED); + if (!hwlock) { pr_warn("a free hwspinlock is not available\n"); - hwlock = NULL; - goto out; + xa_unlock(&hwspinlock_xa); + return NULL; } - /* sanity check that should never fail */ - WARN_ON(ret > 1); - /* mark as used and power up */ + __xa_clear_tag(&hwspinlock_xa, index, HWSPINLOCK_UNUSED); + xa_unlock(&hwspinlock_xa); + ret = __hwspin_lock_request(hwlock); - if (ret < 0) - hwlock = NULL; + if (ret == 0) + return hwlock; -out: - mutex_unlock(&hwspinlock_tree_lock); - return hwlock; + xa_set_tag(&hwspinlock_xa, index, HWSPINLOCK_UNUSED); + return NULL; } EXPORT_SYMBOL_GPL(hwspin_lock_request); @@ -592,10 +548,10 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id) struct hwspinlock *hwlock; int ret; - mutex_lock(&hwspinlock_tree_lock); + xa_lock(&hwspinlock_xa); /* make sure this hwspinlock exists */ - hwlock = radix_tree_lookup(&hwspinlock_tree, id); + hwlock = xa_load(&hwspinlock_xa, id); if (!hwlock) { pr_warn("hwspinlock %u does not exist\n", id); goto out; @@ -605,21 +561,25 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id) WARN_ON(hwlock_to_id(hwlock) != id); /* make sure this hwspinlock is unused */ - ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); + ret = xa_get_tag(&hwspinlock_xa, id, HWSPINLOCK_UNUSED); if (ret == 0) { pr_warn("hwspinlock %u is already in use\n", id); - hwlock = NULL; goto out; } /* mark as used and power up */ + __xa_clear_tag(&hwspinlock_xa, id, HWSPINLOCK_UNUSED); + xa_unlock(&hwspinlock_xa); + ret = __hwspin_lock_request(hwlock); - if (ret < 0) - hwlock = NULL; + if (ret == 0) + return hwlock; + xa_set_tag(&hwspinlock_xa, id, HWSPINLOCK_UNUSED); + return NULL; out: - mutex_unlock(&hwspinlock_tree_lock); - return hwlock; + xa_unlock(&hwspinlock_xa); + return NULL; } EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); @@ -638,7 +598,6 @@ EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); int hwspin_lock_free(struct hwspinlock *hwlock) { struct device *dev; - struct hwspinlock *tmp; int ret; if (!hwlock) { @@ -647,12 +606,11 @@ int hwspin_lock_free(struct hwspinlock *hwlock) } dev = hwlock->bank->dev; - mutex_lock(&hwspinlock_tree_lock); /* make sure the hwspinlock is used */ - ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock), + ret = xa_get_tag(&hwspinlock_xa, hwlock_to_id(hwlock), HWSPINLOCK_UNUSED); - if (ret == 1) { + if (ret) { dev_err(dev, "%s: hwlock is already free\n", __func__); dump_stack(); ret = -EINVAL; @@ -665,16 +623,11 @@ int hwspin_lock_free(struct hwspinlock *hwlock) goto out; /* mark this hwspinlock as available */ - tmp = radix_tree_tag_set(&hwspinlock_tree, hwlock_to_id(hwlock), - HWSPINLOCK_UNUSED); - - /* sanity check (this shouldn't happen) */ - WARN_ON(tmp != hwlock); + xa_set_tag(&hwspinlock_xa, hwlock_to_id(hwlock), HWSPINLOCK_UNUSED); module_put(dev->driver->owner); out: - mutex_unlock(&hwspinlock_tree_lock); return ret; } EXPORT_SYMBOL_GPL(hwspin_lock_free); -- 2.15.1 -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html