From: "Matthew Wilcox (Oracle)" <[email protected]> The radix tree is deprecated. The XArray uses the same data structure with a nicer interface. The hwspinlock_tree_lock is not needed as the spinlock built into the XArray is sufficient for all these cases after we split a larger critical section in hwspin_lock_request_specific() into two smaller ones.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> Co-developed-by: Wolfram Sang <[email protected]> Signed-off-by: Wolfram Sang <[email protected]> --- drivers/hwspinlock/hwspinlock_core.c | 160 +++++++++++---------------- 1 file changed, 65 insertions(+), 95 deletions(-) diff --git a/drivers/hwspinlock/hwspinlock_core.c b/drivers/hwspinlock/hwspinlock_core.c index a509b73da190..e2b7a2271de6 100644 --- a/drivers/hwspinlock/hwspinlock_core.c +++ b/drivers/hwspinlock/hwspinlock_core.c @@ -16,7 +16,7 @@ #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> @@ -27,35 +27,21 @@ /* retry delay used in atomic context */ #define HWSPINLOCK_RETRY_DELAY_US 100 -/* radix tree tags */ -#define HWSPINLOCK_UNUSED (0) /* tags an hwspinlock as unused */ +/* XArray search mark */ +#define HWSPINLOCK_UNUSED XA_MARK_0 /* marks a hwspinlock as unused */ /* - * A radix tree is used to maintain the available hwspinlock instances. + * An XArray is used to maintain the available hwspinlock instances. * The tree 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 + * XArrays are 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. - */ -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. + * used as the ID of the hwspinlock instances). */ -static DEFINE_MUTEX(hwspinlock_tree_lock); - +static DEFINE_XARRAY(hwspinlocks); /** * __hwspin_trylock() - attempt to lock a specific hwspinlock @@ -369,10 +355,9 @@ 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, &hwspinlocks, 0); struct of_phandle_args args; struct hwspinlock *hwlock; - struct radix_tree_iter iter; - void **slot; int id; int ret; @@ -389,15 +374,9 @@ 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 (device_match_of_node(hwlock->bank->dev, args.np)) { ret = 0; break; @@ -452,51 +431,50 @@ EXPORT_SYMBOL_GPL(of_hwspin_lock_get_id_byname); static int hwspin_lock_register_single(struct hwspinlock *hwlock, int id) { - struct hwspinlock *tmp; + XA_STATE(xas, &hwspinlocks, id); + struct hwspinlock *existing; int ret; - mutex_lock(&hwspinlock_tree_lock); - - ret = radix_tree_insert(&hwspinlock_tree, id, hwlock); - if (ret) { - if (ret == -EEXIST) + do { + xas_lock(&xas); + existing = xas_load(&xas); + if (existing) { 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); + xas_set_err(&xas, -EBUSY); + } + xas_store(&xas, hwlock); - /* self-sanity check which should never fail */ - WARN_ON(tmp != hwlock); + /* mark this hwspinlock as available */ + xas_set_mark(&xas, HWSPINLOCK_UNUSED); + ret = xas_error(&xas); + xas_unlock(&xas); + } while (xas_nomem(&xas, GFP_KERNEL)); -out: - mutex_unlock(&hwspinlock_tree_lock); return ret; } static struct hwspinlock *hwspin_lock_unregister_single(unsigned int id) { + XA_STATE(xas, &hwspinlocks, id); struct hwspinlock *hwlock = NULL; - int ret; + bool unused; - mutex_lock(&hwspinlock_tree_lock); + xas_lock(&xas); + xas_load(&xas); - /* make sure the hwspinlock is not in use (tag is set) */ - ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); - if (ret == 0) { + /* make sure the hwspinlock is not in use (mark is set) */ + unused = xas_get_mark(&xas, HWSPINLOCK_UNUSED); + if (!unused) { 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 = xas_store(&xas, NULL); + if (!hwlock) + pr_err("hwspinlock %d already deleted\n", id); out: - mutex_unlock(&hwspinlock_tree_lock); + xas_unlock(&xas); return hwlock; } @@ -666,20 +644,18 @@ int devm_hwspin_lock_register(struct device *dev, EXPORT_SYMBOL_GPL(devm_hwspin_lock_register); /** - * __hwspin_lock_request() - tag an hwspinlock as used and power it up + * hwspin_lock_prepare() - prepare a hwspinlock * @hwlock: the target hwspinlock * * 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) */ -static int __hwspin_lock_request(struct hwspinlock *hwlock) +static int hwspin_lock_prepare(struct hwspinlock *hwlock) { struct device *dev = hwlock->bank->dev; - struct hwspinlock *tmp; int ret; /* prevent underlying implementation from being removed */ @@ -697,16 +673,7 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock) return ret; } - ret = 0; - - /* 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; + return 0; } /** @@ -724,13 +691,14 @@ static int __hwspin_lock_request(struct hwspinlock *hwlock) */ struct hwspinlock *hwspin_lock_request_specific(unsigned int id) { + XA_STATE(xas, &hwspinlocks, id); struct hwspinlock *hwlock; + bool unused; int ret; - mutex_lock(&hwspinlock_tree_lock); + xas_lock(&xas); - /* make sure this hwspinlock exists */ - hwlock = radix_tree_lookup(&hwspinlock_tree, id); + hwlock = xas_load(&xas); if (!hwlock) { pr_warn("hwspinlock %u does not exist\n", id); goto out; @@ -739,21 +707,25 @@ struct hwspinlock *hwspin_lock_request_specific(unsigned int id) /* sanity check (this shouldn't happen) */ WARN_ON(hwlock_to_id(hwlock) != id); - /* make sure this hwspinlock is unused */ - ret = radix_tree_tag_get(&hwspinlock_tree, id, HWSPINLOCK_UNUSED); - if (ret == 0) { + unused = xas_get_mark(&xas, HWSPINLOCK_UNUSED); + if (!unused) { pr_warn("hwspinlock %u is already in use\n", id); hwlock = NULL; goto out; } - /* mark as used and power up */ - ret = __hwspin_lock_request(hwlock); - if (ret < 0) - hwlock = NULL; + xas_clear_mark(&xas, HWSPINLOCK_UNUSED); + xas_unlock(&xas); + ret = hwspin_lock_prepare(hwlock); + + xas_lock(&xas); + if (ret < 0) { + hwlock = NULL; + xas_set_mark(&xas, HWSPINLOCK_UNUSED); + } out: - mutex_unlock(&hwspinlock_tree_lock); + xas_unlock(&xas); return hwlock; } EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); @@ -772,9 +744,10 @@ EXPORT_SYMBOL_GPL(hwspin_lock_request_specific); */ int hwspin_lock_free(struct hwspinlock *hwlock) { + XA_STATE(xas, &hwspinlocks, 0); struct device *dev; - struct hwspinlock *tmp; - int ret; + bool unused; + int ret = 0; if (!hwlock) { pr_err("invalid hwlock\n"); @@ -782,12 +755,13 @@ int hwspin_lock_free(struct hwspinlock *hwlock) } dev = hwlock->bank->dev; - mutex_lock(&hwspinlock_tree_lock); + xas_lock(&xas); + xas_set(&xas, hwlock_to_id(hwlock)); + xas_load(&xas); /* make sure the hwspinlock is used */ - ret = radix_tree_tag_get(&hwspinlock_tree, hwlock_to_id(hwlock), - HWSPINLOCK_UNUSED); - if (ret == 1) { + unused = xas_get_mark(&xas, HWSPINLOCK_UNUSED); + if (unused) { dev_err(dev, "%s: hwlock is already free\n", __func__); dump_stack(); ret = -EINVAL; @@ -798,16 +772,12 @@ int hwspin_lock_free(struct hwspinlock *hwlock) pm_runtime_put(dev); /* 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); + xas_set_mark(&xas, HWSPINLOCK_UNUSED); module_put(dev->driver->owner); out: - mutex_unlock(&hwspinlock_tree_lock); + xas_unlock(&xas); return ret; } EXPORT_SYMBOL_GPL(hwspin_lock_free); -- 2.51.0
