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Brian Norris 218b71e32f tracefs: Only clobber mode/uid/gid on remount if asked
[ Upstream commit 47311db8e8 ]

Users may have explicitly configured their tracefs permissions; we
shouldn't overwrite those just because a second mount appeared.

Only clobber if the options were provided at mount time.

Note: the previous behavior was especially surprising in the presence of
automounted /sys/kernel/debug/tracing/.

Existing behavior:

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwx------

  ## Unexpected: the automount changed mode for other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwx------

New behavior (after this change):

  ## Pre-existing status: tracefs is 0755.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

  ## (Re)trigger the automount.
  # umount /sys/kernel/debug/tracing
  # stat -c '%A' /sys/kernel/debug/tracing/.
  drwxr-xr-x

  ## Expected: the automount does not change other mount instances.
  # stat -c '%A' /sys/kernel/tracing/
  drwxr-xr-x

Link: https://lkml.kernel.org/r/20220826174353.2.Iab6e5ea57963d6deca5311b27fb7226790d44406@changeid

Cc: stable@vger.kernel.org
Fixes: 4282d60689 ("tracefs: Add new tracefs file system")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-09-20 12:38:31 +02:00
arch ARM: dts: imx6qdl-kontron-samx6i: fix spi-flash compatible 2022-09-20 12:38:30 +02:00
block blk-mq: fix io hung due to missing commit_rqs 2022-08-31 17:15:24 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-21 15:16:22 +02:00
Documentation arm64: errata: add detection for AMEVCNTR01 incrementing incorrectly 2022-09-15 11:32:06 +02:00
drivers iommu/vt-d: Correctly calculate sagaw value of IOMMU 2022-09-20 12:38:31 +02:00
fs tracefs: Only clobber mode/uid/gid on remount if asked 2022-09-20 12:38:31 +02:00
include debugfs: add debugfs_lookup_and_remove() 2022-09-15 11:32:03 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:21:25 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:21:17 +02:00
kernel swiotlb: avoid potential left shift overflow 2022-09-15 11:32:06 +02:00
lib lib/vdso: Mark do_hres_timens() and do_coarse_timens() __always_inline() 2022-09-05 10:28:58 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()" 2022-09-15 11:32:02 +02:00
net sch_sfb: Also store skb len before calling child enqueue 2022-09-15 11:32:06 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts kbuild: Fix include path in scripts/Makefile.modpost 2022-09-05 10:28:55 +02:00
security apparmor: Fix memleak in aa_simple_write_to_buffer() 2022-08-25 11:37:53 +02:00
sound ASoC: mchp-spdiftx: Fix clang -Wbitfield-constant-conversion 2022-09-15 11:32:06 +02:00
tools perf python: Fix build when PYTHON_CONFIG is user supplied 2022-08-31 17:15:24 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Add infrastructure and macro to mark VM as bugged 2022-08-21 15:16:24 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Amir as xfs maintainer for 5.10.y 2022-07-02 16:39:22 +02:00
Makefile Linux 5.10.143 2022-09-15 11:32:07 +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.