From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/md/dm-path-selector.c | 138 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 138 insertions(+) create mode 100644 drivers/md/dm-path-selector.c (limited to 'drivers/md/dm-path-selector.c') diff --git a/drivers/md/dm-path-selector.c b/drivers/md/dm-path-selector.c new file mode 100644 index 000000000..006a7991f --- /dev/null +++ b/drivers/md/dm-path-selector.c @@ -0,0 +1,138 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2003 Sistina Software. + * Copyright (C) 2004 Red Hat, Inc. All rights reserved. + * + * Module Author: Heinz Mauelshagen + * + * This file is released under the GPL. + * + * Path selector registration. + */ + +#include +#include + +#include "dm-path-selector.h" + +#include + +struct ps_internal { + struct path_selector_type pst; + struct list_head list; +}; + +#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) + +static LIST_HEAD(_path_selectors); +static DECLARE_RWSEM(_ps_lock); + +static struct ps_internal *__find_path_selector_type(const char *name) +{ + struct ps_internal *psi; + + list_for_each_entry(psi, &_path_selectors, list) { + if (!strcmp(name, psi->pst.name)) + return psi; + } + + return NULL; +} + +static struct ps_internal *get_path_selector(const char *name) +{ + struct ps_internal *psi; + + down_read(&_ps_lock); + psi = __find_path_selector_type(name); + if (psi && !try_module_get(psi->pst.module)) + psi = NULL; + up_read(&_ps_lock); + + return psi; +} + +struct path_selector_type *dm_get_path_selector(const char *name) +{ + struct ps_internal *psi; + + if (!name) + return NULL; + + psi = get_path_selector(name); + if (!psi) { + request_module("dm-%s", name); + psi = get_path_selector(name); + } + + return psi ? &psi->pst : NULL; +} + +void dm_put_path_selector(struct path_selector_type *pst) +{ + struct ps_internal *psi; + + if (!pst) + return; + + down_read(&_ps_lock); + psi = __find_path_selector_type(pst->name); + if (!psi) + goto out; + + module_put(psi->pst.module); +out: + up_read(&_ps_lock); +} + +static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) +{ + struct ps_internal *psi = kzalloc_obj(*psi); + + if (psi) + psi->pst = *pst; + + return psi; +} + +int dm_register_path_selector(struct path_selector_type *pst) +{ + int r = 0; + struct ps_internal *psi = _alloc_path_selector(pst); + + if (!psi) + return -ENOMEM; + + down_write(&_ps_lock); + + if (__find_path_selector_type(pst->name)) { + kfree(psi); + r = -EBUSY; + } else + list_add(&psi->list, &_path_selectors); + + up_write(&_ps_lock); + + return r; +} +EXPORT_SYMBOL_GPL(dm_register_path_selector); + +void dm_unregister_path_selector(struct path_selector_type *pst) +{ + struct ps_internal *psi; + + down_write(&_ps_lock); + + psi = __find_path_selector_type(pst->name); + if (WARN_ON(!psi)) { + up_write(&_ps_lock); + return; + } + + list_del(&psi->list); + + up_write(&_ps_lock); + + kfree(psi); +} +EXPORT_SYMBOL_GPL(dm_unregister_path_selector); -- cgit v1.3.1