hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8YPFU CVE: NA
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When I run a stress test about pcie hotplug and removing operations by sysfs, I got a hange task, and the following call trace is printed.
[ 242.683775] INFO: task irq/52-pciehp:128 blocked for more than 120 seconds. [ 242.684615] Not tainted 6.6.0+ #168 [ 242.685065] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 242.685932] task:irq/52-pciehp state:D stack:0 pid:128 ppid:2 flags:0x00000008 [ 242.686858] Call trace: [ 242.687178] __switch_to+0xa8/0xc8 [ 242.687566] __schedule+0x1ec/0x4a0 [ 242.688019] schedule+0x2c/0x80 [ 242.688382] schedule_preempt_disabled+0x18/0x30 [ 242.688905] __mutex_lock.isra.0+0x140/0x2e0 [ 242.689385] __mutex_lock_slowpath+0x1c/0x30 [ 242.689867] mutex_lock+0x6c/0x88 [ 242.690239] pci_lock_rescan_remove+0x24/0x38 [ 242.690346] EXT4-fs error (device vda): ext4_lookup:1857: inode #37226: comm systemd-journal: deleted inode referenced: 41314 [ 242.690730] pciehp_configure_device+0x34/0x168 [ 242.692589] board_added+0xf8/0x160 [ 242.692979] __pciehp_enable_slot+0x44/0xf8 [ 242.693446] pciehp_enable_slot+0x40/0xd8 [ 242.693892] pciehp_handle_presence_or_link_change+0xfc/0x208 [ 242.694530] pciehp_ist+0x1c4/0x1d0 [ 242.694920] irq_thread_fn+0x34/0xb8 [ 242.695332] irq_thread+0xd8/0x198 [ 242.695725] kthread+0xe4/0xf0 [ 242.696072] ret_from_fork+0x10/0x20 [ 242.696483] INFO: task bash:432 blocked for more than 120 seconds. [ 242.697176] Not tainted 6.6.0+ #168 [ 242.697625] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 242.698495] task:bash state:D stack:0 pid:432 ppid:400 flags:0x00000008 [ 242.699438] Call trace: [ 242.699726] __switch_to+0xa8/0xc8 [ 242.700116] __schedule+0x1ec/0x4a0 [ 242.700511] schedule+0x2c/0x80 [ 242.700867] __synchronize_irq+0x80/0xc0 [ 242.701308] __free_irq+0xf0/0x308 [ 242.701691] free_irq+0x3c/0x90 [ 242.702046] pcie_shutdown_notification+0x48/0x90 [ 242.702574] pciehp_remove+0x30/0x60 [ 242.702977] pcie_port_remove_service+0x40/0x70 [ 242.703495] device_remove+0x78/0x90 [ 242.703934] __device_release_driver+0x150/0x1c8 [ 242.704453] device_release_driver+0x34/0x58 [ 242.704929] bus_remove_device+0xd8/0x158 [ 242.705374] device_del+0x168/0x2f8 [ 242.705766] device_unregister+0x28/0x88 [ 242.706205] remove_iter+0x34/0x50 [ 242.706585] device_for_each_child+0x64/0xb8 [ 242.707061] pcie_portdrv_remove+0x40/0xb0 [ 242.707525] pci_device_remove+0x44/0xa8 [ 242.708006] device_remove+0x54/0x90 [ 242.708407] __device_release_driver+0x150/0x1c8 [ 242.708921] device_release_driver+0x34/0x58 [ 242.709396] pci_stop_dev+0x44/0xa8 [ 242.709785] pci_stop_bus_device+0x64/0x80 [ 242.710240] pci_stop_and_remove_bus_device_locked+0x60/0xd8 [ 242.710866] remove_store+0x98/0xb0 [ 242.711264] dev_attr_store+0x20/0x40 [ 242.711672] sysfs_kf_write+0x4c/0x68 [ 242.712142] kernfs_fop_write_iter+0x130/0x1c8 [ 242.712641] new_sync_write+0xa4/0x128 [ 242.713060] vfs_write.part.0+0x128/0x168 [ 242.713503] vfs_write+0x9c/0xf0 [ 242.713864] ksys_write+0x74/0x108 [ 242.714245] __arm64_sys_write+0x24/0x38 [ 242.714682] invoke_syscall.constprop.0+0x54/0xe8 [ 242.715214] el0_svc_common.constprop.0+0x44/0xc8 [ 242.715752] do_el0_svc+0x1c/0x40 [ 242.716125] el0_svc+0x4c/0xd8 [ 242.716470] el0t_64_sync_handler+0xc0/0xc8 [ 242.716936] el0t_64_sync+0x1a4/0x1a8
When we remove a slot by sysfs. 'pci_stop_and_remove_bus_device_locked()' will be called. This function will get the global mutex lock 'pci_rescan_remove_lock', and remove the slot. If the irq thread 'pciehp_ist' is still running, we will wait until it exits.
If a pciehp interrupt happens immediately after we remove the slot by sysfs, but before we free the pciehp irq in 'pci_stop_and_remove_bus_device_locked()'. 'pciehp_ist' will hung because the global mutex lock 'pci_rescan_remove_lock' is held by the sysfs operation. But the sysfs operation is waiting for the pciehp irq thread 'pciehp_ist' ends. Then a hung task occurs.
So this two kinds of operation, removing through attention buttion and removing through /sys/devices/pci***/remove, should not be excuted at the same time. This patch add a global variable to mark that one of these operations is under processing. When this variable is set, if another operation is requested, it will be rejected.
We use a global variable 'slot_being_removed_rescaned' to mark whether a slot is being removed or rescaned. This will cause a slot hotplug operation is delayed if another slot is being remove or rescaned. But if these two slots are under different root ports, they should not influence each other. This patch make the flag 'slot_being_removed_rescanned' per root port so that one slot hotplug operation doesn't influence slots below another root port.
We record the root port in struct pci_dev when the pci device is initialized and added into the system instead of using 'pcie_find_root_port()' to find the root port when we need it. Because iterating the pci tree needs the protection of 'pci_lock_rescan_remove()'. This will make the problem more complexed because the lock is very coarse-grained. We don't need to worry about 'use-after-free' because child pci devices are always removed before the root port device is removed.
Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com Reviewed-by: Hanjun Guo guohanjun@huawei.com
Conflicts: drivers/pci/hotplug/pciehp_ctrl.c drivers/pci/hotplug/pciehp_hpc.c include/linux/pci.h Signed-off-by: Xiongfeng Wang wangxiongfeng2@huawei.com --- drivers/pci/hotplug/pciehp.h | 5 ++ drivers/pci/hotplug/pciehp_ctrl.c | 40 ++++++++++++++++ drivers/pci/hotplug/pciehp_hpc.c | 79 ++++++++++++++++++++++++++----- drivers/pci/pci-sysfs.c | 22 +++++++++ drivers/pci/probe.c | 5 ++ include/linux/pci.h | 8 ++++ include/linux/workqueue.h | 2 + 7 files changed, 150 insertions(+), 11 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h index e0a614acee05..dad48d151ce2 100644 --- a/drivers/pci/hotplug/pciehp.h +++ b/drivers/pci/hotplug/pciehp.h @@ -199,6 +199,11 @@ static inline const char *slot_name(struct controller *ctrl) return hotplug_slot_name(&ctrl->hotplug_slot); }
+static inline struct pci_dev *ctrl_dev(struct controller *ctrl) +{ + return ctrl->pcie->port; +} + static inline struct controller *to_ctrl(struct hotplug_slot *hotplug_slot) { return container_of(hotplug_slot, struct controller, hotplug_slot); diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index dcdbfcf404dd..458ab6f6379c 100644 --- a/drivers/pci/hotplug/pciehp_ctrl.c +++ b/drivers/pci/hotplug/pciehp_ctrl.c @@ -143,6 +143,8 @@ void pciehp_queue_pushbutton_work(struct work_struct *work) { struct controller *ctrl = container_of(work, struct controller, button_work.work); + int events = ctrl->button_work.data; + struct pci_dev *rpdev = ctrl_dev(ctrl)->rpdev;
mutex_lock(&ctrl->state_lock); switch (ctrl->state) { @@ -153,6 +155,15 @@ void pciehp_queue_pushbutton_work(struct work_struct *work) pciehp_request(ctrl, PCI_EXP_SLTSTA_PDC); break; default: + if (events) { + atomic_or(events, &ctrl->pending_events); + if (!pciehp_poll_mode) + irq_wake_thread(ctrl->pcie->irq, ctrl); + } else { + if (rpdev) + clear_bit(0, + &rpdev->slot_being_removed_rescanned); + } break; } mutex_unlock(&ctrl->state_lock); @@ -160,6 +171,8 @@ void pciehp_queue_pushbutton_work(struct work_struct *work)
void pciehp_handle_button_press(struct controller *ctrl) { + struct pci_dev *rpdev = ctrl_dev(ctrl)->rpdev; + mutex_lock(&ctrl->state_lock); switch (ctrl->state) { case OFF_STATE: @@ -176,6 +189,7 @@ void pciehp_handle_button_press(struct controller *ctrl) /* blink power indicator and turn off attention */ pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_BLINK, PCI_EXP_SLTCTL_ATTN_IND_OFF); + ctrl->button_work.data = 0; schedule_delayed_work(&ctrl->button_work, 5 * HZ); break; case BLINKINGOFF_STATE: @@ -199,10 +213,14 @@ void pciehp_handle_button_press(struct controller *ctrl) ctrl_info(ctrl, "Slot(%s): Button press: canceling request to power on\n", slot_name(ctrl)); } + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); break; default: ctrl_err(ctrl, "Slot(%s): Button press: ignoring invalid state %#x\n", slot_name(ctrl), ctrl->state); + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); break; } mutex_unlock(&ctrl->state_lock); @@ -210,6 +228,8 @@ void pciehp_handle_button_press(struct controller *ctrl)
void pciehp_handle_disable_request(struct controller *ctrl) { + struct pci_dev *rpdev = ctrl_dev(ctrl)->rpdev; + mutex_lock(&ctrl->state_lock); switch (ctrl->state) { case BLINKINGON_STATE: @@ -221,11 +241,14 @@ void pciehp_handle_disable_request(struct controller *ctrl) mutex_unlock(&ctrl->state_lock);
ctrl->request_result = pciehp_disable_slot(ctrl, SAFE_REMOVAL); + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); }
void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) { int present, link_active; + struct pci_dev *rpdev = ctrl_dev(ctrl)->rpdev;
/* * If the slot is on and presence or link has changed, turn it off. @@ -266,6 +289,8 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) slot_name(ctrl)); } mutex_unlock(&ctrl->state_lock); + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); return; }
@@ -288,6 +313,8 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) mutex_unlock(&ctrl->state_lock); break; } + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); }
static int __pciehp_enable_slot(struct controller *ctrl) @@ -408,6 +435,14 @@ int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot) int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot) { struct controller *ctrl = to_ctrl(hotplug_slot); + struct pci_dev *rpdev = ctrl_dev(ctrl)->rpdev; + + if (rpdev && test_and_set_bit(0, + &rpdev->slot_being_removed_rescanned)) { + ctrl_info(ctrl, "Slot(%s): Slot is being removed or rescanned, please try later!\n", + slot_name(ctrl)); + return -EINVAL; + }
mutex_lock(&ctrl->state_lock); switch (ctrl->state) { @@ -418,6 +453,8 @@ int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot) wait_event(ctrl->requester, !atomic_read(&ctrl->pending_events) && !ctrl->ist_running); + if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); return ctrl->request_result; case POWEROFF_STATE: ctrl_info(ctrl, "Slot(%s): Already in powering off state\n", @@ -436,5 +473,8 @@ int pciehp_sysfs_disable_slot(struct hotplug_slot *hotplug_slot) } mutex_unlock(&ctrl->state_lock);
+ if (rpdev) + clear_bit(0, &rpdev->slot_being_removed_rescanned); + return -ENODEV; } diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index fd713abdfb9f..a0fdcd4dc358 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -45,11 +45,6 @@ static const struct dmi_system_id inband_presence_disabled_dmi_table[] = { {} };
-static inline struct pci_dev *ctrl_dev(struct controller *ctrl) -{ - return ctrl->pcie->port; -} - static irqreturn_t pciehp_isr(int irq, void *dev_id); static irqreturn_t pciehp_ist(int irq, void *dev_id); static int pciehp_poll(void *data); @@ -694,6 +689,7 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id) { struct controller *ctrl = (struct controller *)dev_id; struct pci_dev *pdev = ctrl_dev(ctrl); + struct pci_dev *rpdev = pdev->rpdev; irqreturn_t ret; u32 events;
@@ -716,8 +712,20 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id) }
/* Check Attention Button Pressed */ - if (events & PCI_EXP_SLTSTA_ABP) - pciehp_handle_button_press(ctrl); + if (events & PCI_EXP_SLTSTA_ABP) { + if (!rpdev || (rpdev && !test_and_set_bit(0, + &rpdev->slot_being_removed_rescanned))) + pciehp_handle_button_press(ctrl); + else { + if (ctrl->state == BLINKINGOFF_STATE || + ctrl->state == BLINKINGON_STATE) + pciehp_handle_button_press(ctrl); + else + ctrl_info(ctrl, "Slot(%s): Slot operation failed because a remove or" + " rescan operation is under processing, please try later!\n", + slot_name(ctrl)); + } + }
/* Check Power Fault Detected */ if (events & PCI_EXP_SLTSTA_PFD) { @@ -741,10 +749,59 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id) * or Data Link Layer State Changed events. */ down_read_nested(&ctrl->reset_lock, ctrl->depth); - if (events & DISABLE_SLOT) - pciehp_handle_disable_request(ctrl); - else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) - pciehp_handle_presence_or_link_change(ctrl, events); + if (events & DISABLE_SLOT) { + if (!rpdev || (rpdev && !test_and_set_bit(0, + &rpdev->slot_being_removed_rescanned))) + pciehp_handle_disable_request(ctrl); + else { + if (ctrl->state == BLINKINGOFF_STATE || + ctrl->state == BLINKINGON_STATE) + pciehp_handle_disable_request(ctrl); + else { + ctrl_info(ctrl, "Slot(%s): DISABLE_SLOT event in remove or rescan process!\n", + slot_name(ctrl)); + /* + * we use the work_struct private data to store + * the event type + */ + ctrl->button_work.data = DISABLE_SLOT; + /* + * If 'work.timer' is pending, schedule the work will + * cause BUG_ON(). + */ + if (!timer_pending(&ctrl->button_work.timer)) + schedule_delayed_work(&ctrl->button_work, 3 * HZ); + else + ctrl_info(ctrl, "Slot(%s): Didn't schedule delayed_work because timer is pending!\n", + slot_name(ctrl)); + } + } + } else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) { + if (!rpdev || (rpdev && !test_and_set_bit(0, + &rpdev->slot_being_removed_rescanned))) + pciehp_handle_presence_or_link_change(ctrl, events); + else { + if (ctrl->state == BLINKINGOFF_STATE || + ctrl->state == BLINKINGON_STATE) + pciehp_handle_presence_or_link_change(ctrl, + events); + else { + /* + * When we are removing or rescanning through + * sysfs, suprise link down/up happens. So we + * will handle this event 3 seconds later. + */ + ctrl_info(ctrl, "Slot(%s): Surprise link down/up in remove or rescan process!\n", + slot_name(ctrl)); + ctrl->button_work.data = events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC); + if (!timer_pending(&ctrl->button_work.timer)) + schedule_delayed_work(&ctrl->button_work, 3 * HZ); + else + ctrl_info(ctrl, "Slot(%s): Didn't schedule delayed_work because timer is pending!\n", + slot_name(ctrl)); + } + } + } up_read(&ctrl->reset_lock);
ret = IRQ_HANDLED; diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index e3373cdc5244..c7e948b4a5fb 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -484,16 +484,38 @@ static ssize_t remove_store(struct device *dev, struct device_attribute *attr, { unsigned long val; struct pci_dev *pdev = to_pci_dev(dev); + struct pci_dev *rpdev = pdev->rpdev;
if (kstrtoul(buf, 0, &val) < 0) return -EINVAL;
+ if (rpdev && test_and_set_bit(0, + &rpdev->slot_being_removed_rescanned)) { + pr_info("Slot is being removed or rescanned, please try later!\n"); + return -EINVAL; + } + + /* + * if 'dev' is root port itself, 'pci_stop_and_remove_bus_device()' may + * free the 'rpdev', but we need to clear + * 'rpdev->slot_being_removed_rescanned' in the end. So get 'rpdev' to + * avoid possible 'use-after-free'. + */ + if (rpdev) + pci_dev_get(rpdev); + if (val) { pci_dev_get(pdev); if (device_remove_file_self(dev, attr)) pci_stop_and_remove_bus_device_locked(pdev); pci_dev_put(pdev); } + + if (rpdev) { + clear_bit(0, &rpdev->slot_being_removed_rescanned); + pci_dev_put(rpdev); + } + return count; } static DEVICE_ATTR_IGNORE_LOCKDEP(remove, 0220, NULL, diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 1681a9f454f4..ec710d190e6e 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -2584,6 +2584,11 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus) /* Set up MSI IRQ domain */ pci_set_msi_domain(dev);
+ if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT) + dev->rpdev = dev; + else + dev->rpdev = pcie_find_root_port(dev); + /* Notifier could use PCI capabilities */ dev->match_driver = false; ret = device_add(&dev->dev); diff --git a/include/linux/pci.h b/include/linux/pci.h index 9c8d2cddf465..131fa5ce64df 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -529,6 +529,13 @@ struct pci_dev {
/* These methods index pci_reset_fn_methods[] */ u8 reset_methods[PCI_NUM_RESET_METHODS]; /* In priority order */ + + /* + * This flag is only set on root ports. When a slot below a root port + * is being removed or rescanned, this flag is set. + */ + unsigned long slot_being_removed_rescanned; + struct pci_dev *rpdev; /* root port pci_dev */ };
static inline struct pci_dev *pci_physfn(struct pci_dev *dev) @@ -1082,6 +1089,7 @@ extern struct bus_type pci_bus_type; /* Do NOT directly access these two variables, unless you are arch-specific PCI * code, or PCI core code. */ extern struct list_head pci_root_buses; /* List of all known PCI buses */ + /* Some device drivers need know if PCI is initiated */ int no_pci_devices(void);
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 24b1e5070f4d..571dd2ec4381 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -115,6 +115,8 @@ struct delayed_work { /* target workqueue and CPU ->timer uses to queue ->work */ struct workqueue_struct *wq; int cpu; + /* delayed_work private data, only used in pciehp now */ + unsigned long data; };
struct rcu_work {
-
Xiongfeng Wang