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.
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Pull i2c fixes from Wolfram Sang:
"This is a bit larger than usual at rc4 time. The reason is due to
Lee's work of fixing newly reported build warnings.
The rest is fixes as usual"
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (22 commits)
MAINTAINERS: adjust to removing i2c designware platform data
i2c: s3c2410: fix possible NULL pointer deref on read message after write
i2c: mediatek: Disable i2c start_en and clear intr_stat brfore reset
i2c: i801: Don't generate an interrupt on bus reset
i2c: mpc: implement erratum A-004447 workaround
powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P1010 i2c controllers
powerpc/fsl: set fsl,i2c-erratum-a004447 flag for P2041 i2c controllers
dt-bindings: i2c: mpc: Add fsl,i2c-erratum-a004447 flag
i2c: busses: i2c-stm32f4: Remove incorrectly placed ' ' from function name
i2c: busses: i2c-st: Fix copy/paste function misnaming issues
i2c: busses: i2c-pnx: Provide descriptions for 'alg_data' data structure
i2c: busses: i2c-ocores: Place the expected function names into the documentation headers
i2c: busses: i2c-eg20t: Fix 'bad line' issue and provide description for 'msgs' param
i2c: busses: i2c-designware-master: Fix misnaming of 'i2c_dw_init_master()'
i2c: busses: i2c-cadence: Fix incorrectly documented 'enum cdns_i2c_slave_mode'
i2c: busses: i2c-ali1563: File headers are not good candidates for kernel-doc
i2c: muxes: i2c-arb-gpio-challenge: Demote non-conformant kernel-doc headers
i2c: busses: i2c-nomadik: Fix formatting issue pertaining to 'timeout'
i2c: sh_mobile: Use new clock calculation formulas for RZ/G2E
i2c: I2C_HISI should depend on ACPI
...
Pull seccomp fixes from Kees Cook:
"This fixes a hard-to-hit race condition in the addfd user_notif
feature of seccomp, visible since v5.9.
And a small documentation fix"
* tag 'seccomp-fixes-v5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
seccomp: Refactor notification handler to prepare for new semantics
Documentation: seccomp: Fix user notification documentation
Commit 5a517b5bf687 ("i2c: designware: Get rid of legacy platform data")
removes ./include/linux/platform_data/i2c-designware.h, but misses to
adjust the SYNOPSYS DESIGNWARE I2C DRIVER section in MAINTAINERS.
Hence, ./scripts/get_maintainer.pl --self-test=patterns complains:
warning: no file matches F: include/linux/platform_data/i2c-designware.h
Remove the file entry to this removed file as well.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Pull RISC-V fixes from Palmer Dabbelt:
"A handful of RISC-V related fixes:
- avoid errors when the stack tracing code is tracing itself.
- resurrect the memtest= kernel command line argument on RISC-V,
which was briefly enabled during the merge window before a
refactoring disabled it.
- build fix and some warning cleanups"
* tag 'riscv-for-linus-5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
riscv: kexec: Fix W=1 build warnings
riscv: kprobes: Fix build error when MMU=n
riscv: Select ARCH_USE_MEMTEST
riscv: stacktrace: fix the riscv stacktrace when CONFIG_FRAME_POINTER enabled
This refactors the user notification code to have a do / while loop around
the completion condition. This has a small change in semantic, in that
previously we ignored addfd calls upon wakeup if the notification had been
responded to, but instead with the new change we check for an outstanding
addfd calls prior to returning to userspace.
Rodrigo Campos also identified a bug that can result in addfd causing
an early return, when the supervisor didn't actually handle the
syscall [1].
[1]: https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/
Fixes: 7cf97b125455 ("seccomp: Introduce addfd ioctl to seccomp user notifier")
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Tycho Andersen <tycho@tycho.pizza>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Rodrigo Campos <rodrigo@kinvolk.io>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210517193908.3113-3-sargun@sargun.me
Interrupt handler processes multiple message write requests one after
another, till the driver message queue is drained. However if driver
encounters a read message without preceding START, it stops the I2C
transfer as it is an invalid condition for the controller. At least the
comment describes a requirement "the controller forces us to send a new
START when we change direction". This stop results in clearing the
message queue (i2c->msg = NULL).
The code however immediately jumped back to label "retry_write" which
dereferenced the "i2c->msg" making it a possible NULL pointer
dereference.
The Coverity analysis:
1. Condition !is_msgend(i2c), taking false branch.
if (!is_msgend(i2c)) {
2. Condition !is_lastmsg(i2c), taking true branch.
} else if (!is_lastmsg(i2c)) {
3. Condition i2c->msg->flags & 1, taking true branch.
if (i2c->msg->flags & I2C_M_RD) {
4. write_zero_model: Passing i2c to s3c24xx_i2c_stop, which sets i2c->msg to NULL.
s3c24xx_i2c_stop(i2c, -EINVAL);
5. Jumping to label retry_write.
goto retry_write;
6. var_deref_model: Passing i2c to is_msgend, which dereferences null i2c->msg.
if (!is_msgend(i2c)) {"
All previous calls to s3c24xx_i2c_stop() in this interrupt service
routine are followed by jumping to end of function (acknowledging
the interrupt and returning). This seems a reasonable choice also here
since message buffer was entirely emptied.
Addresses-Coverity: Explicit null dereferenced
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Pull xfs fixes from Darrick Wong:
"This week's pile mitigates some decades-old problems in how extent
size hints interact with realtime volumes, fixes some failures in
online shrink, and fixes a problem where directory and symlink
shrinking on extremely fragmented filesystems could fail.
The most user-notable change here is to point users at our (new) IRC
channel on OFTC. Freedom isn't free, it costs folks like you and me;
and if you don't kowtow, they'll expel everyone and take over your
channel. (Ok, ok, that didn't fit the song lyrics...)
Summary:
- Fix a bug where unmapping operations end earlier than expected,
which can cause chaos on multi-block directory and symlink shrink
operations.
- Fix an erroneous assert that can trigger if we try to transition a
bmap structure from btree format to extents format with zero
extents. This was exposed by xfs/538"
* tag 'xfs-5.13-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: bunmapi has unnecessary AG lock ordering issues
xfs: btree format inode forks can have zero extents
xfs: add new IRC channel to MAINTAINERS
xfs: validate extsz hints against rt extent size when rtinherit is set
xfs: standardize extent size hint validation
xfs: check free AG space when making per-AG reservations
Fixes the following W=1 build warning(s):
In file included from include/linux/kexec.h:28,
from arch/riscv/kernel/machine_kexec.c:7:
arch/riscv/include/asm/kexec.h:45:1: warning: ‘extern’ is not at beginning of declaration [-Wold-style-declaration]
45 | const extern unsigned char riscv_kexec_relocate[];
| ^~~~~
arch/riscv/include/asm/kexec.h:46:1: warning: ‘extern’ is not at beginning of declaration [-Wold-style-declaration]
46 | const extern unsigned int riscv_kexec_relocate_size;
| ^~~~~
arch/riscv/kernel/machine_kexec.c:125:6: warning: no previous prototype for ‘machine_shutdown’ [-Wmissing-prototypes]
125 | void machine_shutdown(void)
| ^~~~~~~~~~~~~~~~
arch/riscv/kernel/machine_kexec.c:147:1: warning: no previous prototype for ‘machine_crash_shutdown’ [-Wmissing-prototypes]
147 | machine_crash_shutdown(struct pt_regs *regs)
| ^~~~~~~~~~~~~~~~~~~~~~
arch/riscv/kernel/machine_kexec.c:23: warning: Function parameter or member 'image' not described in 'kexec_image_info'
arch/riscv/kernel/machine_kexec.c:53: warning: Function parameter or member 'image' not described in 'machine_kexec_prepare'
arch/riscv/kernel/machine_kexec.c:114: warning: Function parameter or member 'image' not described in 'machine_kexec_cleanup'
arch/riscv/kernel/machine_kexec.c:148: warning: Function parameter or member 'regs' not described in 'machine_crash_shutdown'
arch/riscv/kernel/machine_kexec.c:167: warning: Function parameter or member 'image' not described in 'machine_kexec'
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
The documentation had some previously incorrect information about how
userspace notifications (and responses) were handled due to a change
from a previously proposed patchset.
Signed-off-by: Sargun Dhillon <sargun@sargun.me>
Acked-by: Tycho Andersen <tycho@tycho.pizza>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Fixes: 6a21cc50f0c7 ("seccomp: add a return code to trap to userspace")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210517193908.3113-2-sargun@sargun.me
The i2c controller driver do dma reset after transfer timeout,
but sometimes dma reset will trigger an unexpected DMA_ERR irq.
It will cause the i2c controller to continuously send interrupts
to the system and cause soft lock-up. So we need to disable i2c
start_en and clear intr_stat to stop i2c controller before dma
reset when transfer timeout.
Fixes: aafced673c06("i2c: mediatek: move dma reset before i2c reset")
Signed-off-by: Qii Wang <qii.wang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Pull thermal fixes from Daniel Lezcano:
- Fix uninitialized error code value for the SPMI adc driver (Yang
Yingliang)
- Fix kernel doc warning (Yang Li)
- Fix wrong read-write thermal trip point initialization (Srinivas
Pandruvada)
* tag 'thermal-v5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/thermal/linux:
thermal/drivers/qcom: Fix error code in adc_tm5_get_dt_channel_data()
thermal/ti-soc-thermal: Fix kernel-doc
thermal/drivers/intel: Initialize RW trip to THERMAL_TEMP_INVALID
large directory block size operations are assert failing because
xfs_bunmapi() is not completely removing fragmented directory blocks
like so:
XFS: Assertion failed: done, file: fs/xfs/libxfs/xfs_dir2.c, line: 677
....
Call Trace:
xfs_dir2_shrink_inode+0x1a8/0x210
xfs_dir2_block_to_sf+0x2ae/0x410
xfs_dir2_block_removename+0x21a/0x280
xfs_dir_removename+0x195/0x1d0
xfs_rename+0xb79/0xc50
? avc_has_perm+0x8d/0x1a0
? avc_has_perm_noaudit+0x9a/0x120
xfs_vn_rename+0xdb/0x150
vfs_rename+0x719/0xb50
? __lookup_hash+0x6a/0xa0
do_renameat2+0x413/0x5e0
__x64_sys_rename+0x45/0x50
do_syscall_64+0x3a/0x70
entry_SYSCALL_64_after_hwframe+0x44/0xae
We are aborting the bunmapi() pass because of this specific chunk of
code:
/*
* Make sure we don't touch multiple AGF headers out of order
* in a single transaction, as that could cause AB-BA deadlocks.
*/
if (!wasdel && !isrt) {
agno = XFS_FSB_TO_AGNO(mp, del.br_startblock);
if (prev_agno != NULLAGNUMBER && prev_agno > agno)
break;
prev_agno = agno;
}
This is designed to prevent deadlocks in AGF locking when freeing
multiple extents by ensuring that we only ever lock in increasing
AG number order. Unfortunately, this also violates the "bunmapi will
always succeed" semantic that some high level callers depend on,
such as xfs_dir2_shrink_inode(), xfs_da_shrink_inode() and
xfs_inactive_symlink_rmt().
This AG lock ordering was introduced back in 2017 to fix deadlocks
triggered by generic/299 as reported here:
https://lore.kernel.org/linux-xfs/800468eb-3ded-9166-20a4-047de8018582@gmail.com/
This codebase is old enough that it was before we were defering all
AG based extent freeing from within xfs_bunmapi(). THat is, we never
actually lock AGs in xfs_bunmapi() any more - every non-rt based
extent free is added to the defer ops list, as is all BMBT block
freeing. And RT extents are not RT based, so there's no lock
ordering issues associated with them.
Hence this AGF lock ordering code is both broken and dead. Let's
just remove it so that the large directory block code works reliably
again.
Tested against xfs/538 and generic/299 which is the original test
that exposed the deadlocks that this code fixed.
Fixes: 5b094d6dac04 ("xfs: fix multi-AG deadlock in xfs_bunmapi")
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
lkp reported a randconfig failure:
arch/riscv/kernel/probes/kprobes.c:90:22: error: use of undeclared identifier 'PAGE_KERNEL_READ_EXEC'
We implemented the alloc_insn_page() to allocate PAGE_KERNEL_READ_EXEC
page for kprobes insn page for STRICT_MODULE_RWX. But if MMU=n, we
should fall back to the generic weak alloc_insn_page() by generic
kprobe subsystem.
Fixes: cdd1b2bd358f ("riscv: kprobes: Implement alloc_insn_page()")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>