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Filename Latest commit message Latest commit date
Vineeth Vijayan a470819824 s390/cio: dont call css_wait_for_slow_path() inside a lock
commit c749d8c018daf5fba6dfac7b6c5c78b27efd7d65 upstream.

Currently css_wait_for_slow_path() gets called inside the chp->lock.
The path-verification-loop of slowpath inside this lock could lead to
deadlock as reported by the lockdep validator.

The ccw_device_get_chp_desc() during the instance of a device-set-online
would try to acquire the same 'chp->lock' to read the chp->desc.
The instance of this function can get called from multiple scenario,
like probing or setting-device online manually. This could, in some
corner-cases lead to the deadlock.

lockdep validator reported this as,

        CPU0                    CPU1
        ----                    ----
   lock(&chp->lock);
                                lock(kn->active#43);
                                lock(&chp->lock);
   lock((wq_completion)cio);

The chp->lock was introduced to serialize the access of struct
channel_path. This lock is not needed for the css_wait_for_slow_path()
function, so invoke the slow-path function outside this lock.

Fixes: b730f3a933 ("[S390] cio: add lock to struct channel_path")
Cc: <stable@vger.kernel.org>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-14 16:53:05 +02:00
arch KVM: PPC: Book3S HV: Workaround high stack usage with clang 2021-07-14 16:53:05 +02:00
block
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto
Documentation
drivers s390/cio: dont call css_wait_for_slow_path() inside a lock 2021-07-14 16:53:05 +02:00
fs ext4: use ext4_grp_locked_error in mb_find_extent 2021-07-14 16:53:03 +02:00
include certs: Add EFI_CERT_X509_GUID support for dbx entries 2021-06-30 08:47:55 -04:00
init
ipc
kernel mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:55 -04:00
lib iov_iter_fault_in_readable() should do nothing in xarray case 2021-07-14 16:53:01 +02:00
LICENSES
mm mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:55 -04:00
net SUNRPC: Should wake up the privileged task firstly. 2021-07-14 16:53:05 +02:00
samples
scripts recordmcount: Correct st_shndx handling 2021-06-30 08:47:49 -04:00
security x86/efi: remove unused variables 2021-07-07 08:22:58 -04:00
sound ALSA: hda/realtek: Apply LED fixup for HP Dragonfly G1, too 2021-07-14 16:52:59 +02:00
tools KVM: selftests: Fix kvm_check_cap() assertion 2021-06-30 08:47:49 -04:00
usr
virt KVM: do not allow mapping valid but non-reference-counted pages 2021-06-30 08:47:50 -04:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.131 2021-07-11 12:52:08 +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.