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Qian Cai d261d0bd90 powerpc/eeh_cache: Fix a possible debugfs deadlock
[ Upstream commit fd552e0542 ]

Lockdep complains that a possible deadlock below in
eeh_addr_cache_show() because it is acquiring a lock with IRQ enabled,
but eeh_addr_cache_insert_dev() needs to acquire the same lock with IRQ
disabled. Let's just make eeh_addr_cache_show() acquire the lock with
IRQ disabled as well.

        CPU0                    CPU1
        ----                    ----
   lock(&pci_io_addr_cache_root.piar_lock);
                                local_irq_disable();
                                lock(&tp->lock);
                                lock(&pci_io_addr_cache_root.piar_lock);
   <Interrupt>
     lock(&tp->lock);

  *** DEADLOCK ***

  lock_acquire+0x140/0x5f0
  _raw_spin_lock_irqsave+0x64/0xb0
  eeh_addr_cache_insert_dev+0x48/0x390
  eeh_probe_device+0xb8/0x1a0
  pnv_pcibios_bus_add_device+0x3c/0x80
  pcibios_bus_add_device+0x118/0x290
  pci_bus_add_device+0x28/0xe0
  pci_bus_add_devices+0x54/0xb0
  pcibios_init+0xc4/0x124
  do_one_initcall+0xac/0x528
  kernel_init_freeable+0x35c/0x3fc
  kernel_init+0x24/0x148
  ret_from_kernel_thread+0x5c/0x80

  lock_acquire+0x140/0x5f0
  _raw_spin_lock+0x4c/0x70
  eeh_addr_cache_show+0x38/0x110
  seq_read+0x1a0/0x660
  vfs_read+0xc8/0x1f0
  ksys_read+0x74/0x130
  system_call_exception+0xf8/0x1d0
  system_call_common+0xe8/0x218

Fixes: 5ca85ae631 ("powerpc/eeh_cache: Add a way to dump the EEH address cache")
Signed-off-by: Qian Cai <cai@redhat.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201028152717.8967-1-cai@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-11-18 19:20:18 +01:00
Documentation linkage: Introduce new macros for assembler symbols 2020-11-10 12:37:24 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch powerpc/eeh_cache: Fix a possible debugfs deadlock 2020-11-18 19:20:18 +01:00
block blk-cgroup: Pre-allocate tree node on blkg_conf_prep 2020-11-10 12:37:30 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto crypto: algif_skcipher - EBUSY on aio should be an error 2020-10-29 09:57:30 +01:00
drivers hv_balloon: disable warning when floor reached 2020-11-18 19:20:17 +01:00
fs xfs: set xefi_discard when creating a deferred agfl free log intent item 2020-11-18 19:20:17 +01:00
include netfilter: nf_tables: missing validation from the abort path 2020-11-18 19:20:17 +01:00
init printk: reduce LOG_BUF_SHIFT range for H8300 2020-11-05 11:43:16 +01:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel genirq: Let GENERIC_IRQ_IPI select IRQ_DOMAIN_HIERARCHY 2020-11-18 19:20:16 +01:00
lib lib/crc32test: remove extra local_irq_disable/enable 2020-11-10 12:37:27 +01:00
mm mm: mempolicy: fix potential pte_unmap_unlock pte error 2020-11-10 12:37:27 +01:00
net netfilter: ipset: Update byte and packet counters regardless of whether they match 2020-11-18 19:20:17 +01:00
samples samples/bpf: Fix possible deadlock in xdpsock 2020-11-05 11:43:17 +01:00
scripts scripts/setlocalversion: make git describe output more reliable 2020-11-01 12:01:01 +01:00
security evm: Check size of security.evm before using it 2020-11-01 12:01:05 +01:00
sound ASoC: codecs: wcd9335: Set digital gain range correctly 2020-11-18 19:20:17 +01:00
tools perf python scripting: Fix printable strings in python3 scripts 2020-11-05 11:43:32 +01:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm64: Force PTE mapping on fault resulting in a device mapping 2020-11-18 19:20:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.77 2020-11-10 21:13:20 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.