From patchwork Wed Jan 17 20:21:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 10170989 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9F435603B5 for ; Wed, 17 Jan 2018 20:32:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8FB3F205FD for ; Wed, 17 Jan 2018 20:32:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 842E3212E8; Wed, 17 Jan 2018 20:32:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CB30C205FD for ; Wed, 17 Jan 2018 20:32:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754415AbeAQUbd (ORCPT ); Wed, 17 Jan 2018 15:31:33 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:44605 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753561AbeAQUXC (ORCPT ); Wed, 17 Jan 2018 15:23:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9fFOAysuk6CpybOi5z6t/NaeM/YYdaODArkHgkzRsis=; b=WSoOtgatCLpCUeTvpzk9c4VOA MfUpxOiKWxAMaXdY0H0Hvjt9d8KFFhYZFAsK/luEqbeS+Rv6oTpdhJYe0eQlhxsVR3BllstHCpD3/ NZf8v6M61nmC3HvbURCGFbA9228kayELGRDoSoEmFahrgT1h878/KD/g2IvMmDBwZAPzsESd8EOby ZqThVt8V6enO1EUNWNMpekdFYSxlUCPLmBnDP0T2sL8QofElaBF8U9R0eGb5yi9NFpNCVkXCbA2sc hzIY+MkqWg2rqwFQfhLzYpLXsgwyuZxffa/e0Eko55dWaaAQNDdj6yzAfA9BAqJUZVAM3kPYXmama bKm94WSBA==; Received: from willy by bombadil.infradead.org with local (Exim 4.89 #1 (Red Hat Linux)) id 1ebuEe-0006GA-9m; Wed, 17 Jan 2018 20:23:00 +0000 From: Matthew Wilcox To: linux-kernel@vger.kernel.org Cc: Matthew Wilcox , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, Bjorn Andersson , Stefano Stabellini , iommu@lists.linux-foundation.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org, linux-sh@vger.kernel.org, David Howells Subject: [PATCH v6 83/99] hwspinlock: Convert to XArray Date: Wed, 17 Jan 2018 12:21:47 -0800 Message-Id: <20180117202203.19756-84-willy@infradead.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180117202203.19756-1-willy@infradead.org> References: <20180117202203.19756-1-willy@infradead.org> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Matthew Wilcox 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 --- 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 #include #include -#include +#include #include #include -#include #include #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);