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synced 2026-11-01 23:04:54 +01:00
Dan Williams
6575b26815
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 <[email protected]>
Closes: http://lore.kernel.org/[email protected]
Tested-by: Gregory Price <[email protected]>
Fixes: 8dd2bc0f8e ("cxl/mem: Add the cxl_mem driver")
Cc: [email protected]
Cc: Davidlohr Bueso <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Alison Schofield <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Ira Weiny <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Tested-by: Alejandro Lucero <[email protected]>
Reviewed-by: Alejandro Lucero <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Link: https://patch.msgid.link/172988474904.476062.7961350937442459266.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Ira Weiny <[email protected]>
22 lines
688 B
Makefile
22 lines
688 B
Makefile
# 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-$(CONFIG_CXL_PORT) += cxl_port.o
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obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
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obj-$(CONFIG_CXL_PMEM) += cxl_pmem.o
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obj-$(CONFIG_CXL_MEM) += cxl_mem.o
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obj-$(CONFIG_CXL_PCI) += cxl_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_mem-y := mem.o
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cxl_pci-y := pci.o
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