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cxl/port: Fix CXL port initialization order when the subsystem is built-in
When the CXL subsystem is built-in the module init order is determined
by Makefile order. That order violates expectations. The expectation is
that cxl_acpi and cxl_mem can race to attach. If cxl_acpi wins the race,
cxl_mem will find the enabled CXL root ports it needs. If cxl_acpi loses
the race it will retrigger cxl_mem to attach via cxl_bus_rescan(). That
flow only works if cxl_acpi can assume ports are enabled immediately
upon cxl_acpi_probe() return. That in turn can only happen in the
CONFIG_CXL_ACPI=y case if the cxl_port driver is registered before
cxl_acpi_probe() runs.
Fix up the order to prevent initialization failures. Ensure that
cxl_port is built-in when cxl_acpi is also built-in, arrange for
Makefile order to resolve the subsys_initcall() order of cxl_port and
cxl_acpi, and arrange for Makefile order to resolve the
device_initcall() (module_init()) order of the remaining objects.
As for what contributed to this not being found earlier, the CXL
regression environment, cxl_test, builds all CXL functionality as a
module to allow to symbol mocking and other dynamic reload tests. As a
result there is no regression coverage for the built-in case.
Reported-by: Gregory Price <gourry@gourry.net>
Closes: http://lore.kernel.org/20241004212504.1246-1-gourry@gourry.net
Tested-by: Gregory Price <gourry@gourry.net>
Fixes: 8dd2bc0f8e
("cxl/mem: Add the cxl_mem driver")
Cc: stable@vger.kernel.org
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Alejandro Lucero <alucerop@amd.com>
Reviewed-by: Alejandro Lucero <alucerop@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/172988474904.476062.7961350937442459266.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
This commit is contained in:
parent
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@ -60,6 +60,7 @@ config CXL_ACPI
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default CXL_BUS
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select ACPI_TABLE_LIB
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select ACPI_HMAT
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select CXL_PORT
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help
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Enable support for host managed device memory (HDM) resources
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published by a platform's ACPI CXL memory layout description. See
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@ -1,13 +1,21 @@
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# SPDX-License-Identifier: GPL-2.0
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# Order is important here for the built-in case:
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# - 'core' first for fundamental init
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# - 'port' before platform root drivers like 'acpi' so that CXL-root ports
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# are immediately enabled
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# - 'mem' and 'pmem' before endpoint drivers so that memdevs are
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# immediately enabled
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# - 'pci' last, also mirrors the hardware enumeration hierarchy
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obj-y += core/
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obj-$(CONFIG_CXL_PCI) += cxl_pci.o
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obj-$(CONFIG_CXL_MEM) += cxl_mem.o
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obj-$(CONFIG_CXL_PORT) += cxl_port.o
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obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
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obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
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obj-$(CONFIG_CXL_PORT) += cxl_port.o
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obj-$(CONFIG_CXL_MEM) += cxl_mem.o
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obj-$(CONFIG_CXL_PCI) += cxl_pci.o
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cxl_mem-y := mem.o
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cxl_pci-y := pci.o
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cxl_port-y := port.o
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cxl_acpi-y := acpi.o
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cxl_pmem-y := pmem.o security.o
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cxl_port-y := port.o
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cxl_mem-y := mem.o
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cxl_pci-y := pci.o
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@ -208,7 +208,22 @@ static struct cxl_driver cxl_port_driver = {
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},
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};
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module_cxl_driver(cxl_port_driver);
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static int __init cxl_port_init(void)
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{
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return cxl_driver_register(&cxl_port_driver);
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}
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/*
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* Be ready to immediately enable ports emitted by the platform CXL root
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* (e.g. cxl_acpi) when CONFIG_CXL_PORT=y.
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*/
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subsys_initcall(cxl_port_init);
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static void __exit cxl_port_exit(void)
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{
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cxl_driver_unregister(&cxl_port_driver);
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}
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module_exit(cxl_port_exit);
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MODULE_DESCRIPTION("CXL: Port enumeration and services");
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MODULE_LICENSE("GPL v2");
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MODULE_IMPORT_NS(CXL);
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