kernel/linux.git/drivers, branch v4.19.283

PCI: pciehp: Fix AB-BA deadlock between reset_lock and device_lock

2023-05-17T09:13:28+00:00

commit f5eff5591b8f9c5effd25c92c758a127765f74c1 upstream. In 2013, commits 2e35afaefe64 ("PCI: pciehp: Add reset_slot() method") 608c388122c7 ("PCI: Add slot reset option to pci_dev_reset()") amended PCIe hotplug to mask Presence Detect Changed events during a Secondary Bus Reset. The reset thus no longer causes gratuitous slot bringdown and bringup. However the commits neglected to serialize reset with code paths reading slot registers. For instance, a slot bringup due to an earlier hotplug event may see the Presence Detect State bit cleared during a concurrent Secondary Bus Reset. In 2018, commit 5b3f7b7d062b ("PCI: pciehp: Avoid slot access during reset") retrofitted the missing locking. It introduced a reset_lock which serializes a Secondary Bus Reset with other parts of pciehp. Unfortunately the locking turns out to be overzealous: reset_lock is held for the entire enumeration and de-enumeration of hotplugged devices, including driver binding and unbinding. Driver binding and unbinding acquires device_lock while the reset_lock of the ancestral hotplug port is held. A concurrent Secondary Bus Reset acquires the ancestral reset_lock while already holding the device_lock. The asymmetric locking order in the two code paths can lead to AB-BA deadlocks. Michael Haeuptle reports such deadlocks on simultaneous hot-removal and vfio release (the latter implies a Secondary Bus Reset): pciehp_ist() # down_read(reset_lock) pciehp_handle_presence_or_link_change() pciehp_disable_slot() __pciehp_disable_slot() remove_board() pciehp_unconfigure_device() pci_stop_and_remove_bus_device() pci_stop_bus_device() pci_stop_dev() device_release_driver() device_release_driver_internal() __device_driver_lock() # device_lock() SYS_munmap() vfio_device_fops_release() vfio_device_group_close() vfio_device_close() vfio_device_last_close() vfio_pci_core_close_device() vfio_pci_core_disable() # device_lock() __pci_reset_function_locked() pci_reset_bus_function() pci_dev_reset_slot_function() pci_reset_hotplug_slot() pciehp_reset_slot() # down_write(reset_lock) Ian May reports the same deadlock on simultaneous hot-removal and an AER-induced Secondary Bus Reset: aer_recover_work_func() pcie_do_recovery() aer_root_reset() pci_bus_error_reset() pci_slot_reset() pci_slot_lock() # device_lock() pci_reset_hotplug_slot() pciehp_reset_slot() # down_write(reset_lock) Fix by releasing the reset_lock during driver binding and unbinding, thereby splitting and shrinking the critical section. Driver binding and unbinding is protected by the device_lock() and thus serialized with a Secondary Bus Reset. There's no need to additionally protect it with the reset_lock. However, pciehp does not bind and unbind devices directly, but rather invokes PCI core functions which also perform certain enumeration and de-enumeration steps. The reset_lock's purpose is to protect slot registers, not enumeration and de-enumeration of hotplugged devices. That would arguably be the job of the PCI core, not the PCIe hotplug driver. After all, an AER-induced Secondary Bus Reset may as well happen during boot-time enumeration of the PCI hierarchy and there's no locking to prevent that either. Exempting *de-enumeration* from the reset_lock is relatively harmless: A concurrent Secondary Bus Reset may foil config space accesses such as PME interrupt disablement. But if the device is physically gone, those accesses are pointless anyway. If the device is physically present and only logically removed through an Attention Button press or the sysfs "power" attribute, PME interrupts as well as DMA cannot come through because pciehp_unconfigure_device() disables INTx and Bus Master bits. That's still protected by the reset_lock in the present commit. Exempting *enumeration* from the reset_lock also has limited impact: The exempted call to pci_bus_add_device() may perform device accesses through pcibios_bus_add_device() and pci_fixup_device() which are now no longer protected from a concurrent Secondary Bus Reset. Otherwise there should be no impact. In essence, the present commit seeks to fix the AB-BA deadlocks while still retaining a best-effort reset protection for enumeration and de-enumeration of hotplugged devices -- until a general solution is implemented in the PCI core. Link: https://lore.kernel.org/linux-pci/CS1PR8401MB0728FC6FDAB8A35C22BD90EC95F10@CS1PR8401MB0728.NAMPRD84.PROD.OUTLOOK.COM Link: https://lore.kernel.org/linux-pci/20200615143250.438252-1-ian.may@canonical.com Link: https://lore.kernel.org/linux-pci/ce878dab-c0c4-5bd0-a725-9805a075682d@amd.com Link: https://lore.kernel.org/linux-pci/ed831249-384a-6d35-0831-70af191e9bce@huawei.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=215590 Fixes: 5b3f7b7d062b ("PCI: pciehp: Avoid slot access during reset") Link: https://lore.kernel.org/r/fef2b2e9edf245c049a8c5b94743c0f74ff5008a.1681191902.git.lukas@wunner.de Reported-by: Michael Haeuptle Reported-by: Ian May Reported-by: Andrey Grodzovsky Reported-by: Rahul Kumar Reported-by: Jialin Zhang Tested-by: Anatoli Antonovitch Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org # v4.19+ Cc: Dan Stein Cc: Ashok Raj Cc: Alex Michon Cc: Xiongfeng Wang Cc: Alex Williamson Cc: Mika Westerberg Cc: Sathyanarayanan Kuppuswamy Signed-off-by: Greg Kroah-Hartman

PCI: pciehp: Use down_read/write_nested(reset_lock) to fix lockdep errors

2023-05-17T09:13:28+00:00

commit 085a9f43433f30cbe8a1ade62d9d7827c3217f4d upstream. Use down_read_nested() and down_write_nested() when taking the ctrl->reset_lock rw-sem, passing the number of PCIe hotplug controllers in the path to the PCI root bus as lock subclass parameter. This fixes the following false-positive lockdep report when unplugging a Lenovo X1C8 from a Lenovo 2nd gen TB3 dock: pcieport 0000:06:01.0: pciehp: Slot(1): Link Down pcieport 0000:06:01.0: pciehp: Slot(1): Card not present ============================================ WARNING: possible recursive locking detected 5.16.0-rc2+ #621 Not tainted -------------------------------------------- irq/124-pciehp/86 is trying to acquire lock: ffff8e5ac4299ef8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_check_presence+0x23/0x80 but task is already holding lock: ffff8e5ac4298af8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_ist+0xf3/0x180 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&ctrl->reset_lock); lock(&ctrl->reset_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by irq/124-pciehp/86: #0: ffff8e5ac4298af8 (&ctrl->reset_lock){.+.+}-{3:3}, at: pciehp_ist+0xf3/0x180 #1: ffffffffa3b024e8 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pciehp_unconfigure_device+0x31/0x110 #2: ffff8e5ac1ee2248 (&dev->mutex){....}-{3:3}, at: device_release_driver+0x1c/0x40 stack backtrace: CPU: 4 PID: 86 Comm: irq/124-pciehp Not tainted 5.16.0-rc2+ #621 Hardware name: LENOVO 20U90SIT19/20U90SIT19, BIOS N2WET30W (1.20 ) 08/26/2021 Call Trace: dump_stack_lvl+0x59/0x73 __lock_acquire.cold+0xc5/0x2c6 lock_acquire+0xb5/0x2b0 down_read+0x3e/0x50 pciehp_check_presence+0x23/0x80 pciehp_runtime_resume+0x5c/0xa0 device_for_each_child+0x45/0x70 pcie_port_device_runtime_resume+0x20/0x30 pci_pm_runtime_resume+0xa7/0xc0 __rpm_callback+0x41/0x110 rpm_callback+0x59/0x70 rpm_resume+0x512/0x7b0 __pm_runtime_resume+0x4a/0x90 __device_release_driver+0x28/0x240 device_release_driver+0x26/0x40 pci_stop_bus_device+0x68/0x90 pci_stop_bus_device+0x2c/0x90 pci_stop_and_remove_bus_device+0xe/0x20 pciehp_unconfigure_device+0x6c/0x110 pciehp_disable_slot+0x5b/0xe0 pciehp_handle_presence_or_link_change+0xc3/0x2f0 pciehp_ist+0x179/0x180 This lockdep warning is triggered because with Thunderbolt, hotplug ports are nested. When removing multiple devices in a daisy-chain, each hotplug port's reset_lock may be acquired recursively. It's never the same lock, so the lockdep splat is a false positive. Because locks at the same hierarchy level are never acquired recursively, a per-level lockdep class is sufficient to fix the lockdep warning. The choice to use one lockdep subclass per pcie-hotplug controller in the path to the root-bus was made to conserve class keys because their number is limited and the complexity grows quadratically with number of keys according to Documentation/locking/lockdep-design.rst. Link: https://lore.kernel.org/linux-pci/20190402021933.GA2966@mit.edu/ Link: https://lore.kernel.org/linux-pci/de684a28-9038-8fc6-27ca-3f6f2f6400d7@redhat.com/ Link: https://lore.kernel.org/r/20211217141709.379663-1-hdegoede@redhat.com Link: https://bugzilla.kernel.org/show_bug.cgi?id=208855 Reported-by: "Theodore Ts'o" Signed-off-by: Hans de Goede Signed-off-by: Bjorn Helgaas Reviewed-by: Lukas Wunner Cc: stable@vger.kernel.org [lukas: backport to v4.19-stable] Signed-off-by: Lukas Wunner Signed-off-by: Greg Kroah-Hartman

drbd: correctly submit flush bio on barrier

2023-05-17T09:13:28+00:00

commit 3899d94e3831ee07ea6821c032dc297aec80586a upstream. When we receive a flush command (or "barrier" in DRBD), we currently use a REQ_OP_FLUSH with the REQ_PREFLUSH flag set. The correct way to submit a flush bio is by using a REQ_OP_WRITE without any data, and set the REQ_PREFLUSH flag. Since commit b4a6bb3a67aa ("block: add a sanity check for non-write flush/fua bios"), this triggers a warning in the block layer, but this has been broken for quite some time before that. So use the correct set of flags to actually make the flush happen. Cc: Christoph Hellwig Cc: stable@vger.kernel.org Fixes: f9ff0da56437 ("drbd: allow parallel flushes for multi-volume resources") Reported-by: Thomas Voegtle Signed-off-by: Christoph Böhmwalder Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230503121937.17232-1-christoph.boehmwalder@linbit.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

serial: 8250: Fix serial8250_tx_empty() race with DMA Tx

2023-05-17T09:13:28+00:00

There's a potential race before THRE/TEMT deasserts when DMA Tx is starting up (or the next batch of continuous Tx is being submitted). This can lead to misdetecting Tx empty condition. It is entirely normal for THRE/TEMT to be set for some time after the DMA Tx had been setup in serial8250_tx_dma(). As Tx side is definitely not empty at that point, it seems incorrect for serial8250_tx_empty() claim Tx is empty. Fix the race by also checking in serial8250_tx_empty() whether there's DMA Tx active. Note: This fix only addresses in-kernel race mainly to make using TCSADRAIN/FLUSH robust. Userspace can still cause other races but they seem userspace concurrency control problems. Fixes: 9ee4b83e51f74 ("serial: 8250: Add support for dmaengine") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230317113318.31327-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 146a37e05d620cef4ad430e5d1c9c077fe6fa76f) Signed-off-by: Ilpo Järvinen Signed-off-by: Greg Kroah-Hartman

tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH

2023-05-17T09:13:27+00:00

If userspace races tcsetattr() with a write, the drained condition might not be guaranteed by the kernel. There is a race window after checking Tx is empty before tty_set_termios() takes termios_rwsem for write. During that race window, more characters can be queued by a racing writer. Any ongoing transmission might produce garbage during HW's ->set_termios() call. The intent of TCSADRAIN/FLUSH seems to be preventing such a character corruption. If those flags are set, take tty's write lock to stop any writer before performing the lower layer Tx empty check and wait for the pending characters to be sent (if any). The initial wait for all-writers-done must be placed outside of tty's write lock to avoid deadlock which makes it impossible to use tty_wait_until_sent(). The write lock is retried if a racing write is detected. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230317113318.31327-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 094fb49a2d0d6827c86d2e0840873e6db0c491d2) Signed-off-by: Ilpo Järvinen Signed-off-by: Greg Kroah-Hartman

HID: wacom: Set a default resolution for older tablets

2023-05-17T09:13:26+00:00

commit 08a46b4190d345544d04ce4fe2e1844b772b8535 upstream. Some older tablets may not report physical maximum for X/Y coordinates. Set a default to prevent undefined resolution. Signed-off-by: Ping Cheng Link: https://lore.kernel.org/r/20230409164229.29777-1-ping.cheng@wacom.com Signed-off-by: Benjamin Tissoires Signed-off-by: Greg Kroah-Hartman

drm/panel: otm8009a: Set backlight parent to panel device

2023-05-17T09:13:26+00:00

commit ab4f869fba6119997f7630d600049762a2b014fa upstream. This is the logical place to put the backlight device, and it also fixes a kernel crash if the MIPI host is removed. Previously the backlight device would be unregistered twice when this happened - once as a child of the MIPI host through `mipi_dsi_host_unregister`, and once when the panel device is destroyed. Fixes: 12a6cbd4f3f1 ("drm/panel: otm8009a: Use new backlight API") Signed-off-by: James Cowgill Cc: stable@vger.kernel.org Reviewed-by: Neil Armstrong Signed-off-by: Neil Armstrong Link: https://patchwork.freedesktop.org/patch/msgid/20230412173450.199592-1-james.cowgill@blaize.com Signed-off-by: Greg Kroah-Hartman

platform/x86: touchscreen_dmi: Add info for the Dexp Ursus KX210i

2023-05-17T09:13:26+00:00

commit 4b65f95c87c35699bc6ad540d6b9dd7f950d0924 upstream. Add touchscreen info for the Dexp Ursus KX210i Signed-off-by: Andrey Avdeev Link: https://lore.kernel.org/r/ZE4gRgzRQCjXFYD0@avdeevavpc Cc: stable@vger.kernel.org Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede Signed-off-by: Greg Kroah-Hartman

virtio_net: suppress cpu stall when free_unused_bufs

2023-05-17T09:13:25+00:00

[ Upstream commit f8bb5104394560e29017c25bcade4c6b7aabd108 ] For multi-queue and large ring-size use case, the following error occurred when free_unused_bufs: rcu: INFO: rcu_sched self-detected stall on CPU. Fixes: 986a4f4d452d ("virtio_net: multiqueue support") Signed-off-by: Wenliang Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

virtio_net: split free_unused_bufs()

2023-05-17T09:13:25+00:00

[ Upstream commit 6e345f8c7cd029ad3aaece15ad4425ac26e4eb63 ] This patch separates two functions for freeing sq buf and rq buf from free_unused_bufs(). When supporting the enable/disable tx/rq queue in the future, it is necessary to support separate recovery of a sq buf or a rq buf. Signed-off-by: Xuan Zhuo Acked-by: Jason Wang Message-Id: <20220801063902.129329-40-xuanzhuo@linux.alibaba.com> Signed-off-by: Michael S. Tsirkin Stable-dep-of: f8bb51043945 ("virtio_net: suppress cpu stall when free_unused_bufs") Signed-off-by: Sasha Levin