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Filename Latest commit message Latest commit date
Yicong Yang c9a81f9ed6 PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store()
[ Upstream commit a91ee0e9fca9d7501286cfbced9b30a33e52740a ]

The sysfs sriov_numvfs_store() path acquires the device lock before the
config space access lock:

  sriov_numvfs_store
    device_lock                 # A (1) acquire device lock
    sriov_configure
      vfio_pci_sriov_configure  # (for example)
        vfio_pci_core_sriov_configure
          pci_disable_sriov
            sriov_disable
              pci_cfg_access_lock
                pci_wait_cfg    # B (4) wait for dev->block_cfg_access == 0

Previously, pci_dev_lock() acquired the config space access lock before the
device lock:

  pci_dev_lock
    pci_cfg_access_lock
      dev->block_cfg_access = 1 # B (2) set dev->block_cfg_access = 1
    device_lock                 # A (3) wait for device lock

Any path that uses pci_dev_lock(), e.g., pci_reset_function(), may
deadlock with sriov_numvfs_store() if the operations occur in the sequence
(1) (2) (3) (4).

Avoid the deadlock by reversing the order in pci_dev_lock() so it acquires
the device lock before the config space access lock, the same as the
sriov_numvfs_store() path.

[bhelgaas: combined and adapted commit log from Jay Zhou's independent
subsequent posting:
https://lore.kernel.org/r/20220404062539.1710-1-jianjay.zhou@huawei.com]
Link: https://lore.kernel.org/linux-pci/1583489997-17156-1-git-send-email-yangyicong@hisilicon.com/
Also-posted-by: Jay Zhou <jianjay.zhou@huawei.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-14 18:11:30 +02:00
arch ARM: hisi: Add missing of_node_put after of_find_compatible_node 2022-06-14 18:11:30 +02:00
block block: return ELEVATOR_DISCARD_MERGE if possible 2022-05-25 09:14:38 +02:00
certs
crypto crypto: ecrdsa - Fix incorrect use of vli_cmp 2022-06-06 08:33:50 +02:00
Documentation hwmon: Make chip parameter for with_info API mandatory 2022-06-14 18:11:29 +02:00
drivers PCI: Avoid pci_dev_lock() AB/BA deadlock with sriov_numvfs_store() 2022-06-14 18:11:30 +02:00
fs fat: add ratelimit to fat*_ent_bread() 2022-06-14 18:11:30 +02:00
include ALSA: jack: Access input_dev under mutex 2022-06-14 18:11:25 +02:00
init
ipc
kernel dma-debug: change allocation mode from GFP_NOWAIT to GFP_ATIOMIC 2022-06-14 18:11:28 +02:00
lib assoc_array: Fix BUG_ON during garbage collect 2022-06-06 08:33:50 +02:00
LICENSES
mm zsmalloc: fix races between asynchronous zspage free and page migration 2022-06-06 08:33:50 +02:00
net rxrpc: Return an error to sendmsg if call failed 2022-06-14 18:11:29 +02:00
samples
scripts
security lockdown: also lock down previous kgdb use 2022-06-06 08:33:48 +02:00
sound ASoC: max98357a: remove dependency on GPIOLIB 2022-06-14 18:11:29 +02:00
tools selftests/bpf: fix btf_dump/btf_dump due to recent clang change 2022-06-14 18:11:29 +02:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.197 2022-06-06 08:33:51 +02:00
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.