linux/drivers/cxl
Dan Williams 105b6235ad cxl/port: Prevent out-of-order decoder allocation
With the recent change to allow out-of-order decoder de-commit it
highlights a need to strengthen the in-order decoder commit guarantees.
As it stands match_free_decoder() ensures that if 2 regions are racing
decoder allocations the one that wins the race will get the lower id
decoder, but that still leaves the race to *commit* the decoder.

Rather than have this complicated case of "reserved in-order, but may
still commit out-of-order", just arrange for the reservation order to
match the commit-order. In other words, prevent subsequent allocations
until the last reservation is committed.

This precludes overlapping region creation events and requires the
previous regionN to either move forward to the decoder commit stage or
drop its reservation before regionN+1 can move forward. That is,
provided that regionN and regionN+1 decode through the same switch port.

As a side effect this allows match_free_decoder() to drop its dependency
on needing write access to the device_find_child() @data parameter [1].

Reported-by: Zijun Hu <quic_zijuhu@quicinc.com>
Closes: http://lore.kernel.org/20240905-const_dfc_prepare-v4-0-4180e1d5a244@quicinc.com
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://patch.msgid.link/172964783668.81806.14962699553881333486.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
2024-10-25 16:07:03 -05:00
..
core cxl/port: Prevent out-of-order decoder allocation 2024-10-25 16:07:03 -05:00
acpi.c cxl/acpi: Ensure ports ready at cxl_acpi_probe() return 2024-10-25 16:07:03 -05:00
cxl.h cxl/port: Fix use-after-free, permit out-of-order decoder shutdown 2024-10-25 16:07:03 -05:00
cxlmem.h cxl: Preserve the CDAT access_coordinate for an endpoint 2024-09-22 21:02:53 -07:00
cxlpci.h
Kconfig cxl/port: Fix CXL port initialization order when the subsystem is built-in 2024-10-25 16:06:49 -05:00
Makefile cxl/port: Fix CXL port initialization order when the subsystem is built-in 2024-10-25 16:06:49 -05:00
mem.c cxl/pci: Rename cxl_setup_parent_dport() and cxl_dport_map_regs() 2024-09-03 15:29:33 -07:00
pci.c move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
pmem.c move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00
pmu.h
port.c cxl/port: Fix CXL port initialization order when the subsystem is built-in 2024-10-25 16:06:49 -05:00
security.c move asm/unaligned.h to linux/unaligned.h 2024-10-02 17:23:23 -04:00