From 5c3c067b601bcbcd381214e3a40e666fda5f3d6f Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 8 Feb 2022 23:37:28 -0800 Subject: cxl/core/port: Fix unregister_port() lock assertion The device_lock_assert() in unregister_port() fails to pick the right device leading to splats like the following from: echo "ACPI0017:00" > /sys/bus/platform/drivers/cxl_acpi/unbind WARNING: CPU: 32 PID: 1147 at include/linux/device.h:787 unregister_port+0x49/0x50 [cxl_c [..] RIP: 0010:unregister_port+0x49/0x50 [cxl_core] [..] Call Trace: release_nodes+0x63/0x80 devres_release_all+0x8b/0xc0 __device_release_driver+0x190/0x240 device_driver_detach+0x3e/0xa0 unbind_store+0x113/0x130 Fix it up to assert on the device_lock() for ACPI0017 for root and 1st level ports, and parent ports for all the rest. Fixes: 54cdbf845cf7 ("cxl/port: Add a driver for 'struct cxl_port' objects") Reported-by: Ben Widawsky Reviewed-by: Ben Widawsky Link: https://lore.kernel.org/r/164439224893.2941117.18331456248117887720.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams --- drivers/cxl/core/port.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index c3e83c624700..9b4bbd51fbaa 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -348,12 +348,28 @@ EXPORT_SYMBOL_NS_GPL(to_cxl_port, CXL); static void unregister_port(void *_port) { struct cxl_port *port = _port; + struct cxl_port *parent; + struct device *lock_dev; - if (!is_cxl_root(port)) { - device_lock_assert(port->dev.parent); - port->uport = NULL; - } + if (is_cxl_root(port)) + parent = NULL; + else + parent = to_cxl_port(port->dev.parent); + + /* + * CXL root port's and the first level of ports are unregistered + * under the platform firmware device lock, all other ports are + * unregistered while holding their parent port lock. + */ + if (!parent) + lock_dev = port->uport; + else if (is_cxl_root(parent)) + lock_dev = parent->uport; + else + lock_dev = &parent->dev; + device_lock_assert(lock_dev); + port->uport = NULL; device_unregister(&port->dev); } -- cgit v1.2.3