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Filename Latest commit message Latest commit date
Brendan Higgins 7a9b738c75 Revert "software node: Simplify software_node_release() function"
commit 7589238a8cf37331607c3222a64ac3140b29532d upstream.

This reverts commit 3df85a1ae5.

The reverted commit says "It's possible to release the node ID
immediately when fwnode_remove_software_node() is called, no need to
wait for software_node_release() with that." However, releasing the node
ID before waiting for software_node_release() to be called causes the
node ID to be released before the kobject and the underlying sysfs
entry; this means there is a period of time where a sysfs entry exists
that is associated with an unallocated node ID.

Once consequence of this is that there is a race condition where it is
possible to call fwnode_create_software_node() with no parent node
specified (NULL) and have it fail with -EEXIST because the node ID that
was assigned is still associated with a stale sysfs entry that hasn't
been cleaned up yet.

Although it is difficult to reproduce this race condition under normal
conditions, it can be deterministically reproduced with the following
minconfig on UML:

CONFIG_KUNIT_DRIVER_PE_TEST=y
CONFIG_DEBUG_KERNEL=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_TIMERS=y
CONFIG_DEBUG_KOBJECT_RELEASE=y
CONFIG_KUNIT=y

Running the tests with this configuration causes the following failure:

<snip>
kobject: 'node0' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 400)
	ok 1 - pe_test_uints
sysfs: cannot create duplicate filename '/kernel/software_nodes/node0'
CPU: 0 PID: 28 Comm: kunit_try_catch Not tainted 5.6.0-rc3-next-20200227 #14
<snip>
kobject_add_internal failed for node0 with -EEXIST, don't try to register things with the same name in the same directory.
kobject: 'node0' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 100)
	# pe_test_uint_arrays: ASSERTION FAILED at drivers/base/test/property-entry-test.c:123
	Expected node is not error, but is: -17
	not ok 2 - pe_test_uint_arrays
<snip>

Reported-by: Heidi Fahim <heidifahim@google.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: 5.3+ <stable@vger.kernel.org> # 5.3+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-10 10:31:30 +02:00
arch arm64: vdso: Add -fasynchronous-unwind-tables to cflags 2020-05-06 08:15:17 +02:00
block blk-mq: Put driver tag in blk_mq_dispatch_rq_list() when no budget 2020-05-02 08:48:59 +02:00
certs
crypto crypto: rng - Fix a refcounting bug in crypto_rng_reset() 2020-04-17 10:50:16 +02:00
Documentation USB: hub: Revert commit bd0e6c9614 ("usb: hub: try old enumeration scheme first for high speed devices") 2020-04-29 16:33:14 +02:00
drivers Revert "software node: Simplify software_node_release() function" 2020-05-10 10:31:30 +02:00
fs cifs: do not share tcons with DFS 2020-05-10 10:31:27 +02:00
include drm/bridge: analogix_dp: Split bind() into probe() and real bind() 2020-05-10 10:31:22 +02:00
init printk: queue wake_up_klogd irq_work only if per-CPU areas are ready 2020-05-02 08:48:42 +02:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-29 16:33:00 +02:00
kernel tracing: Fix memory leaks in trace_events_hist.c 2020-05-10 10:31:28 +02:00
lib lib/mpi: Fix building for powerpc with clang 2020-05-10 10:31:28 +02:00
LICENSES
mm mm: shmem: disable interrupt when acquiring info->lock in userfaultfd_copy path 2020-05-02 08:48:54 +02:00
net sctp: Fix SHUTDOWN CTSN Ack in the peer restart case 2020-05-10 10:31:29 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:33:14 +02:00
scripts scripts/config: allow colons in option strings for sed 2020-05-10 10:31:27 +02:00
security selinux: properly handle multiple messages in selinux_netlink_send() 2020-05-06 08:15:17 +02:00
sound ASoC: rsnd: Fix "status check failed" spam for multi-SSI 2020-05-10 10:31:27 +02:00
tools selftests/ipc: Fix test failure seen after initial test run 2020-05-10 10:31:23 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.39 2020-05-06 08:15:17 +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.