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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Mika Westerberg](/assets/img/avatar_default.png)
This addresses deadlocks in these common cases in hierarchies containing two switches: - All involved ports are runtime suspended and they are unplugged. This can happen easily if the drivers involved automatically enable runtime PM (xHCI for example does that). - System is suspended (e.g., closing the lid on a laptop) with a dock + something else connected, and the dock is unplugged while suspended. These cases lead to the following deadlock: INFO: task irq/126-pciehp:198 blocked for more than 120 seconds. irq/126-pciehp D 0 198 2 0x80000000 Call Trace: schedule+0x2c/0x80 schedule_timeout+0x246/0x350 wait_for_completion+0xb7/0x140 kthread_stop+0x49/0x110 free_irq+0x32/0x70 pcie_shutdown_notification+0x2f/0x50 pciehp_remove+0x27/0x50 pcie_port_remove_service+0x36/0x50 device_release_driver+0x12/0x20 bus_remove_device+0xec/0x160 device_del+0x13b/0x350 device_unregister+0x1a/0x60 remove_iter+0x1e/0x30 device_for_each_child+0x56/0x90 pcie_port_device_remove+0x22/0x40 pcie_portdrv_remove+0x20/0x60 pci_device_remove+0x3e/0xc0 device_release_driver_internal+0x18c/0x250 device_release_driver+0x12/0x20 pci_stop_bus_device+0x6f/0x90 pci_stop_bus_device+0x31/0x90 pci_stop_and_remove_bus_device+0x12/0x20 pciehp_unconfigure_device+0x88/0x140 pciehp_disable_slot+0x6a/0x110 pciehp_handle_presence_or_link_change+0x263/0x400 pciehp_ist+0x1c9/0x1d0 irq_thread_fn+0x24/0x60 irq_thread+0xeb/0x190 kthread+0x120/0x140 INFO: task irq/190-pciehp:2288 blocked for more than 120 seconds. irq/190-pciehp D 0 2288 2 0x80000000 Call Trace: __schedule+0x2a2/0x880 schedule+0x2c/0x80 schedule_preempt_disabled+0xe/0x10 mutex_lock+0x2c/0x30 pci_lock_rescan_remove+0x15/0x20 pciehp_unconfigure_device+0x4d/0x140 pciehp_disable_slot+0x6a/0x110 pciehp_handle_presence_or_link_change+0x263/0x400 pciehp_ist+0x1c9/0x1d0 irq_thread_fn+0x24/0x60 irq_thread+0xeb/0x190 kthread+0x120/0x140 What happens here is that the whole hierarchy is runtime resumed and the parent PCIe downstream port, which got the hot-remove event, starts removing devices below it, taking pci_lock_rescan_remove() lock. When the child PCIe port is runtime resumed it calls pciehp_check_presence() which ends up calling pciehp_card_present() and pciehp_check_link_active(). Both of these use pcie_capability_read_word(), which notices that the underlying device is already gone and returns PCIBIOS_DEVICE_NOT_FOUND with the capability value set to 0. When pciehp gets this value it thinks that its child device is also hot-removed and schedules its IRQ thread to handle the event. The deadlock happens when the child's IRQ thread runs and tries to acquire pci_lock_rescan_remove() which is already taken by the parent and the parent waits for the child's IRQ thread to finish. Prevent this from happening by checking the return value of pcie_capability_read_word() and if it is PCIBIOS_DEVICE_NOT_FOUND stop performing any hot-removal activities. [bhelgaas: add common scenarios to commit log] Link: https://lore.kernel.org/r/20191029170022.57528-2-mika.westerberg@linux.intel.com Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
433 lines
11 KiB
C
433 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* PCI Express Hot Plug Controller Driver
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*
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* Copyright (C) 1995,2001 Compaq Computer Corporation
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* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
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* Copyright (C) 2001 IBM Corp.
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* Copyright (C) 2003-2004 Intel Corporation
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*
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* All rights reserved.
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*
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* Send feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
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*
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*/
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#define dev_fmt(fmt) "pciehp: " fmt
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/pm_runtime.h>
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#include <linux/pci.h>
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#include "pciehp.h"
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/* The following routines constitute the bulk of the
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hotplug controller logic
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*/
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#define SAFE_REMOVAL true
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#define SURPRISE_REMOVAL false
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static void set_slot_off(struct controller *ctrl)
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{
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/*
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* Turn off slot, turn on attention indicator, turn off power
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* indicator
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*/
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if (POWER_CTRL(ctrl)) {
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pciehp_power_off_slot(ctrl);
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/*
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* After turning power off, we must wait for at least 1 second
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* before taking any action that relies on power having been
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* removed from the slot/adapter.
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*/
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msleep(1000);
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}
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
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PCI_EXP_SLTCTL_ATTN_IND_ON);
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}
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/**
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* board_added - Called after a board has been added to the system.
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* @ctrl: PCIe hotplug controller where board is added
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*
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* Turns power on for the board.
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* Configures board.
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*/
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static int board_added(struct controller *ctrl)
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{
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int retval = 0;
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struct pci_bus *parent = ctrl->pcie->port->subordinate;
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if (POWER_CTRL(ctrl)) {
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/* Power on slot */
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retval = pciehp_power_on_slot(ctrl);
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if (retval)
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return retval;
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}
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK,
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INDICATOR_NOOP);
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/* Check link training status */
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retval = pciehp_check_link_status(ctrl);
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if (retval) {
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ctrl_err(ctrl, "Failed to check link status\n");
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goto err_exit;
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}
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/* Check for a power fault */
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if (ctrl->power_fault_detected || pciehp_query_power_fault(ctrl)) {
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ctrl_err(ctrl, "Slot(%s): Power fault\n", slot_name(ctrl));
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retval = -EIO;
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goto err_exit;
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}
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retval = pciehp_configure_device(ctrl);
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if (retval) {
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if (retval != -EEXIST) {
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ctrl_err(ctrl, "Cannot add device at %04x:%02x:00\n",
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pci_domain_nr(parent), parent->number);
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goto err_exit;
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}
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}
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_ON,
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PCI_EXP_SLTCTL_ATTN_IND_OFF);
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return 0;
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err_exit:
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set_slot_off(ctrl);
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return retval;
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}
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/**
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* remove_board - Turn off slot and Power Indicator
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* @ctrl: PCIe hotplug controller where board is being removed
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* @safe_removal: whether the board is safely removed (versus surprise removed)
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*/
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static void remove_board(struct controller *ctrl, bool safe_removal)
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{
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pciehp_unconfigure_device(ctrl, safe_removal);
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if (POWER_CTRL(ctrl)) {
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pciehp_power_off_slot(ctrl);
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/*
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* After turning power off, we must wait for at least 1 second
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* before taking any action that relies on power having been
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* removed from the slot/adapter.
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*/
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msleep(1000);
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/* Ignore link or presence changes caused by power off */
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atomic_and(~(PCI_EXP_SLTSTA_DLLSC | PCI_EXP_SLTSTA_PDC),
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&ctrl->pending_events);
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}
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
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INDICATOR_NOOP);
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}
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static int pciehp_enable_slot(struct controller *ctrl);
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static int pciehp_disable_slot(struct controller *ctrl, bool safe_removal);
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void pciehp_request(struct controller *ctrl, int action)
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{
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atomic_or(action, &ctrl->pending_events);
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if (!pciehp_poll_mode)
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irq_wake_thread(ctrl->pcie->irq, ctrl);
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}
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void pciehp_queue_pushbutton_work(struct work_struct *work)
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{
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struct controller *ctrl = container_of(work, struct controller,
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button_work.work);
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case BLINKINGOFF_STATE:
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pciehp_request(ctrl, DISABLE_SLOT);
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break;
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case BLINKINGON_STATE:
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pciehp_request(ctrl, PCI_EXP_SLTSTA_PDC);
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break;
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default:
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break;
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}
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mutex_unlock(&ctrl->state_lock);
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}
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void pciehp_handle_button_press(struct controller *ctrl)
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{
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case OFF_STATE:
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case ON_STATE:
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if (ctrl->state == ON_STATE) {
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ctrl->state = BLINKINGOFF_STATE;
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ctrl_info(ctrl, "Slot(%s): Powering off due to button press\n",
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slot_name(ctrl));
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} else {
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ctrl->state = BLINKINGON_STATE;
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ctrl_info(ctrl, "Slot(%s) Powering on due to button press\n",
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slot_name(ctrl));
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}
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/* blink power indicator and turn off attention */
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK,
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PCI_EXP_SLTCTL_ATTN_IND_OFF);
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schedule_delayed_work(&ctrl->button_work, 5 * HZ);
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break;
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case BLINKINGOFF_STATE:
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case BLINKINGON_STATE:
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/*
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* Cancel if we are still blinking; this means that we
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* press the attention again before the 5 sec. limit
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* expires to cancel hot-add or hot-remove
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*/
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ctrl_info(ctrl, "Slot(%s): Button cancel\n", slot_name(ctrl));
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cancel_delayed_work(&ctrl->button_work);
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if (ctrl->state == BLINKINGOFF_STATE) {
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ctrl->state = ON_STATE;
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_ON,
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PCI_EXP_SLTCTL_ATTN_IND_OFF);
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} else {
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ctrl->state = OFF_STATE;
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
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PCI_EXP_SLTCTL_ATTN_IND_OFF);
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}
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ctrl_info(ctrl, "Slot(%s): Action canceled due to button press\n",
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slot_name(ctrl));
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break;
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default:
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ctrl_err(ctrl, "Slot(%s): Ignoring invalid state %#x\n",
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slot_name(ctrl), ctrl->state);
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break;
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}
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mutex_unlock(&ctrl->state_lock);
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}
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void pciehp_handle_disable_request(struct controller *ctrl)
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{
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case BLINKINGON_STATE:
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case BLINKINGOFF_STATE:
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cancel_delayed_work(&ctrl->button_work);
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break;
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}
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ctrl->state = POWEROFF_STATE;
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mutex_unlock(&ctrl->state_lock);
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ctrl->request_result = pciehp_disable_slot(ctrl, SAFE_REMOVAL);
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}
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void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
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{
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int present, link_active;
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/*
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* If the slot is on and presence or link has changed, turn it off.
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* Even if it's occupied again, we cannot assume the card is the same.
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*/
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case BLINKINGOFF_STATE:
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cancel_delayed_work(&ctrl->button_work);
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/* fall through */
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case ON_STATE:
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ctrl->state = POWEROFF_STATE;
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mutex_unlock(&ctrl->state_lock);
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if (events & PCI_EXP_SLTSTA_DLLSC)
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ctrl_info(ctrl, "Slot(%s): Link Down\n",
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slot_name(ctrl));
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if (events & PCI_EXP_SLTSTA_PDC)
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ctrl_info(ctrl, "Slot(%s): Card not present\n",
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slot_name(ctrl));
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pciehp_disable_slot(ctrl, SURPRISE_REMOVAL);
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break;
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default:
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mutex_unlock(&ctrl->state_lock);
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break;
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}
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/* Turn the slot on if it's occupied or link is up */
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mutex_lock(&ctrl->state_lock);
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present = pciehp_card_present(ctrl);
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link_active = pciehp_check_link_active(ctrl);
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if (present <= 0 && link_active <= 0) {
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mutex_unlock(&ctrl->state_lock);
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return;
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}
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switch (ctrl->state) {
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case BLINKINGON_STATE:
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cancel_delayed_work(&ctrl->button_work);
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/* fall through */
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case OFF_STATE:
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ctrl->state = POWERON_STATE;
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mutex_unlock(&ctrl->state_lock);
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if (present)
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ctrl_info(ctrl, "Slot(%s): Card present\n",
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slot_name(ctrl));
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if (link_active)
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ctrl_info(ctrl, "Slot(%s): Link Up\n",
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slot_name(ctrl));
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ctrl->request_result = pciehp_enable_slot(ctrl);
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break;
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default:
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mutex_unlock(&ctrl->state_lock);
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break;
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}
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}
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static int __pciehp_enable_slot(struct controller *ctrl)
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{
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u8 getstatus = 0;
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if (MRL_SENS(ctrl)) {
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pciehp_get_latch_status(ctrl, &getstatus);
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if (getstatus) {
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ctrl_info(ctrl, "Slot(%s): Latch open\n",
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slot_name(ctrl));
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return -ENODEV;
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}
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}
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if (POWER_CTRL(ctrl)) {
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pciehp_get_power_status(ctrl, &getstatus);
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if (getstatus) {
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ctrl_info(ctrl, "Slot(%s): Already enabled\n",
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slot_name(ctrl));
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return 0;
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}
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}
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return board_added(ctrl);
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}
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static int pciehp_enable_slot(struct controller *ctrl)
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{
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int ret;
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pm_runtime_get_sync(&ctrl->pcie->port->dev);
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ret = __pciehp_enable_slot(ctrl);
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if (ret && ATTN_BUTTN(ctrl))
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/* may be blinking */
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pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF,
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INDICATOR_NOOP);
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pm_runtime_put(&ctrl->pcie->port->dev);
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mutex_lock(&ctrl->state_lock);
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ctrl->state = ret ? OFF_STATE : ON_STATE;
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mutex_unlock(&ctrl->state_lock);
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return ret;
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}
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static int __pciehp_disable_slot(struct controller *ctrl, bool safe_removal)
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{
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u8 getstatus = 0;
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if (POWER_CTRL(ctrl)) {
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pciehp_get_power_status(ctrl, &getstatus);
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if (!getstatus) {
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ctrl_info(ctrl, "Slot(%s): Already disabled\n",
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slot_name(ctrl));
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return -EINVAL;
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}
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}
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remove_board(ctrl, safe_removal);
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return 0;
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}
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static int pciehp_disable_slot(struct controller *ctrl, bool safe_removal)
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{
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int ret;
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pm_runtime_get_sync(&ctrl->pcie->port->dev);
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ret = __pciehp_disable_slot(ctrl, safe_removal);
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pm_runtime_put(&ctrl->pcie->port->dev);
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mutex_lock(&ctrl->state_lock);
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ctrl->state = OFF_STATE;
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mutex_unlock(&ctrl->state_lock);
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return ret;
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}
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int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot)
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{
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struct controller *ctrl = to_ctrl(hotplug_slot);
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case BLINKINGON_STATE:
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case OFF_STATE:
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mutex_unlock(&ctrl->state_lock);
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/*
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* The IRQ thread becomes a no-op if the user pulls out the
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* card before the thread wakes up, so initialize to -ENODEV.
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*/
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ctrl->request_result = -ENODEV;
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pciehp_request(ctrl, PCI_EXP_SLTSTA_PDC);
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wait_event(ctrl->requester,
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!atomic_read(&ctrl->pending_events) &&
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!ctrl->ist_running);
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return ctrl->request_result;
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case POWERON_STATE:
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ctrl_info(ctrl, "Slot(%s): Already in powering on state\n",
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slot_name(ctrl));
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break;
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case BLINKINGOFF_STATE:
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case ON_STATE:
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case POWEROFF_STATE:
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ctrl_info(ctrl, "Slot(%s): Already enabled\n",
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slot_name(ctrl));
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break;
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default:
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ctrl_err(ctrl, "Slot(%s): Invalid state %#x\n",
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slot_name(ctrl), ctrl->state);
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break;
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}
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mutex_unlock(&ctrl->state_lock);
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return -ENODEV;
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}
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int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot)
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{
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struct controller *ctrl = to_ctrl(hotplug_slot);
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mutex_lock(&ctrl->state_lock);
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switch (ctrl->state) {
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case BLINKINGOFF_STATE:
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case ON_STATE:
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mutex_unlock(&ctrl->state_lock);
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pciehp_request(ctrl, DISABLE_SLOT);
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wait_event(ctrl->requester,
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!atomic_read(&ctrl->pending_events) &&
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!ctrl->ist_running);
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return ctrl->request_result;
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case POWEROFF_STATE:
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ctrl_info(ctrl, "Slot(%s): Already in powering off state\n",
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slot_name(ctrl));
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break;
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case BLINKINGON_STATE:
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case OFF_STATE:
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case POWERON_STATE:
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ctrl_info(ctrl, "Slot(%s): Already disabled\n",
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slot_name(ctrl));
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break;
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default:
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ctrl_err(ctrl, "Slot(%s): Invalid state %#x\n",
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slot_name(ctrl), ctrl->state);
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break;
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}
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mutex_unlock(&ctrl->state_lock);
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return -ENODEV;
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}
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