[RFC,02/11] drivers/base: Add hotplug framework code

Message ID	1355354243-18657-3-git-send-email-toshi.kani@hp.com (mailing list archive)
State	RFC, archived
Headers	show Return-Path: <linux-acpi-owner@vger.kernel.org> From: Toshi Kani <toshi.kani@hp.com> To: rjw@sisk.pl, lenb@kernel.org, gregkh@linuxfoundation.org, akpm@linux-foundation.org Cc: linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bhelgaas@google.com, isimatu.yasuaki@jp.fujitsu.com, jiang.liu@huawei.com, wency@cn.fujitsu.com, guohanjun@huawei.com, yinghai@kernel.org, srivatsa.bhat@linux.vnet.ibm.com, Toshi Kani <toshi.kani@hp.com> Subject: [RFC PATCH 02/11] drivers/base: Add hotplug framework code Date: Wed, 12 Dec 2012 16:17:14 -0700 Message-Id: <1355354243-18657-3-git-send-email-toshi.kani@hp.com> In-Reply-To: <1355354243-18657-1-git-send-email-toshi.kani@hp.com> References: <1355354243-18657-1-git-send-email-toshi.kani@hp.com> Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk

diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 5aa2d70..af2e013 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -21,6 +21,7 @@ endif obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o obj-$(CONFIG_REGMAP) += regmap/ obj-$(CONFIG_SOC_BUS) += soc.o +obj-$(CONFIG_HOTPLUG) += hotplug.o ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG diff --git a/drivers/base/hotplug.c b/drivers/base/hotplug.c new file mode 100644 index 0000000..9e85e25 --- /dev/null +++ b/drivers/base/hotplug.c @@ -0,0 +1,283 @@ +/* + * hotplug.c - Hot-plug framework for system devices + * + * Copyright (C) 2012 Hewlett-Packard Development Company, L.P. + * Toshi Kani <toshi.kani@hp.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <linux/list.h> +#include <linux/workqueue.h> +#include <linux/hotplug.h> +#include <linux/kallsyms.h> + +/* + * Hot-plug handler list + */ +struct hp_handler { + struct list_head hp_list; + int hp_order; + hp_func hp_func; +}; + +LIST_HEAD(hp_add_list_head); +LIST_HEAD(hp_del_list_head); + +#define HP_VALIDATE_ORDER_BASE (HP_ORDER_MAX+1) +#define HP_EXECUTE_ORDER_BASE ((HP_ORDER_MAX+1) << 1) +#define HP_COMMIT_ORDER_BASE ((HP_ORDER_MAX+1) << 2) + +/* + * Hot-plug request work queue + */ +struct hp_work { + struct hp_request *request; + struct work_struct work; +}; + +static struct workqueue_struct *hp_workqueue; + +/* trace messages */ +static int hp_trace = 1; +static char hp_ksym_buf[KSYM_NAME_LEN]; + +static char *hp_operation_string(enum hp_operation operation) +{ + switch (operation) { + case HP_HOTPLUG_ADD: + return "Hot-Add"; + case HP_HOTPLUG_DEL: + return "Hot-Delete"; + case HP_ONLINE_ADD: + return "Online"; + case HP_ONLINE_DEL: + return "Offline"; + } + + return "n/a"; +} + +static u32 hp_get_order_base(enum hp_phase phase) +{ + switch (phase) { + case HP_ADD_VALIDATE: + case HP_DEL_VALIDATE: + return HP_VALIDATE_ORDER_BASE; + case HP_ADD_EXECUTE: + case HP_DEL_EXECUTE: + return HP_EXECUTE_ORDER_BASE; + case HP_ADD_COMMIT: + case HP_DEL_COMMIT: + return HP_COMMIT_ORDER_BASE; + } + + return 0; +} + +/** + * hp_register_handler - register a hot-plug handler to the framework + * @phase: hot-plug phase + * @func: Hot-plug function + * @order: Pre-defined order value + */ +int hp_register_handler(enum hp_phase phase, hp_func func, u32 order) +{ + struct list_head *head; + struct hp_handler *hdr, *cur; + u32 order_base; + int insert = 0; + + if (!func || order > HP_ORDER_MAX) + return -EINVAL; + + if (hp_is_add_phase(phase)) + head = &hp_add_list_head; + else + head = &hp_del_list_head; + + order_base = hp_get_order_base(phase); + + hdr = kzalloc(sizeof(*hdr), GFP_KERNEL); + if (!hdr) + return -ENOMEM; + + hdr->hp_order = order + order_base; + hdr->hp_func = func; + + /* + * Add this handler to the list in ascending order + */ + if (list_empty(head)) { + list_add(&hdr->hp_list, head); + } else { + list_for_each_entry(cur, head, hp_list) + if (cur->hp_order > hdr->hp_order) { + insert = 1; + break; + } + + if (insert) + __list_add(&hdr->hp_list, + cur->hp_list.prev, &cur->hp_list); + else + list_add_tail(&hdr->hp_list, head); + } + + return 0; +} +EXPORT_SYMBOL(hp_register_handler); + +/** + * hp_unregister_handler - unregister a hot-plug handler from the framework + * @phase: hot-plug phase + * @func: Hot-plug function + */ +int hp_unregister_handler(enum hp_phase phase, hp_func func) +{ + /* REVISIT: implement later */ + return 0; +} +EXPORT_SYMBOL(hp_unregister_handler); + +static void hp_start_req(struct work_struct *work) +{ + struct hp_work *hp_work = container_of(work, struct hp_work, work); + struct hp_request *req = hp_work->request; + struct hp_handler *hdr; + struct hp_device *hp_dev, *tmp; + struct list_head *head; + int rollback = 0; + int ret; + + if (hp_is_add_op(req->operation)) + head = &hp_add_list_head; + else + head = &hp_del_list_head; + + if (hp_trace) + pr_info("Starting %s Operation\n", + hp_operation_string(req->operation)); + + /* + * Call hot-plug handlers in the list + */ + list_for_each_entry(hdr, head, hp_list) { + if (hp_trace) + pr_info("-> %s\n", + kallsyms_lookup((unsigned long)hdr->hp_func, + NULL, NULL, NULL, hp_ksym_buf)); + + ret = hdr->hp_func(req, 0); + if (ret) { + if (hdr->hp_order < HP_COMMIT_ORDER_BASE) { + if (hp_trace) + pr_info("Initiating Rollback\n"); + rollback = 1; + break; + } else { + pr_err("Commit handler failed: continuing\n"); + continue; + } + } + } + + /* + * If rollback is requested, call hot-plug handlers in the reversed + * order from the failed handler. The failed handler is not called + * again. + */ + if (rollback) { + list_for_each_entry_continue_reverse(hdr, head, hp_list) { + if (hp_trace) + pr_info("RB-> %s\n", + kallsyms_lookup( + (unsigned long)hdr->hp_func, + NULL, NULL, NULL, hp_ksym_buf)); + + ret = hdr->hp_func(req, 1); + if (ret) + pr_err("Rollback handler failed: continuing\n"); + } + } + + /* free up the hot-plug request information */ + list_for_each_entry_safe(hp_dev, tmp, &req->dev_list, list) { + list_del(&hp_dev->list); + kfree(hp_dev); + } + kfree(req); + kfree(hp_work); +} + +/** + * hp_submit_req - submit a hot-plug request + * @req: Hot-plug request pointer + */ +int hp_submit_req(struct hp_request *req) +{ + struct hp_work *hp_work; + + hp_work = kzalloc(sizeof(*hp_work), GFP_KERNEL); + if (!hp_work) + return -ENOMEM; + + hp_work->request = req; + INIT_WORK(&hp_work->work, hp_start_req); + + if (!queue_work(hp_workqueue, &hp_work->work)) { + kfree(hp_work); + return -EINVAL; + } + + return 0; +} +EXPORT_SYMBOL(hp_submit_req); + +/** + * hp_alloc_request - allocate a hot-plug request + * @operation: Hot-plug operation + */ +struct hp_request *hp_alloc_request(enum hp_operation operation) +{ + struct hp_request *hp_req; + + hp_req = kzalloc(sizeof(*hp_req), GFP_KERNEL); + if (!hp_req) + return NULL; + + hp_req->operation = operation; + INIT_LIST_HEAD(&hp_req->dev_list); + + return hp_req; +} +EXPORT_SYMBOL(hp_alloc_request); + +/** + * hp_add_dev_info - add hp_device to the hotplug request + * @hp_req: hot-plug request pointer + * @hp_dev: hot-plug device info pointer + */ +void hp_add_dev_info(struct hp_request *hp_req, struct hp_device *hp_dev) +{ + list_add_tail(&hp_dev->list, &hp_req->dev_list); +} +EXPORT_SYMBOL(hp_add_dev_info); + +static int __init hp_init(void) +{ + /* + * Allocate hp_workqueue with max_active set to 1. This serializes + * hot-plug and online/offline operations on the workqueue. + */ + hp_workqueue = alloc_workqueue("hotplug", 0, 1); + + return 0; +} +device_initcall(hp_init);

[RFC,02/11] drivers/base: Add hotplug framework code

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