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When the link is down, config accesses to downstream devices cause CPU
aborts. Allow config accesses only when the link is up.
As the following scenario shows, this check is racy and cannot completely
avoid CPU aborts, but it makes them less likely:
pci_generic_config_read
addr = brcm_pcie_map_conf # bus->ops->map_bus()
brcm_pcie_link_up # returns "true"; link is up
<link goes down>
*val = readb(addr) # link is now down
<CPU abort>
Note that config space accesses to the Root Port are not affected by link
status.
[bhelgaas: commit log, use PCIE_ECAM_REG() instead of magic 0xfff masks;
note that pci_generic_config_read32() masks low two bits already]
Link: https://lore.kernel.org/r/20220725151258.42574-4-jim2101024@gmail.com
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.