tjh.dev
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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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Pull scheduler fix from Ingo Molnar:
"Fix a context switch performance regression"
* tag 'sched-urgent-2020-12-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Optimize finish_lock_switch()
Commit c9a3c4e637ac ("mfd: ab8500-debugfs: Remove extraneous curly
brace") removed a left-over curly brace that caused build failures, but
Joe Perches points out that the subsequent 'seq_putc()' should also be
removed, because the commit that caused all these problems already added
the final '\n' to the seq_printf() above it.
Reported-by: Joe Perches <joe@perches.com>
Fixes: 886c8121659d ("mfd: ab8500-debugfs: Remove the racy fiddling with irq_desc")
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel test robot measured a -1.6% performance regression on
will-it-scale/sched_yield due to commit:
2558aacff858 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")
Even though we were careful to replace a single load with another
single load from the same cacheline.
Restore finish_lock_switch() to the exact state before the offending
patch and solve the problem differently.
Fixes: 2558aacff858 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201210161408.GX3021@hirez.programming.kicks-ass.net
Pull PCI fixes from Bjorn Helgaas:
- Fix a tegra enumeration regression (Rob Herring)
- Fix a designware-host check that warned on *success*, not failure
(Alexander Lobakin)
* tag 'pci-v5.11-fixes-1' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
PCI: dwc: Fix inverted condition of DMA mask setup warning
PCI: tegra: Fix host link initialization
idle_balance() has been renamed to newidle_balance(). To differentiate
with nohz_idle_balance, it seems refining the comment will be helpful
for the readers of the code.
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20201202220641.22752-1-song.bao.hua@hisilicon.com
Clang errors:
drivers/mfd/ab8500-debugfs.c:1526:2: error: non-void function does not return a value [-Werror,-Wreturn-type]
}
^
drivers/mfd/ab8500-debugfs.c:1528:2: error: expected identifier or '('
return 0;
^
drivers/mfd/ab8500-debugfs.c:1529:1: error: extraneous closing brace ('}')
}
^
3 errors generated.
The cleanup in ab8500_interrupts_show left a curly brace around, remove
it to fix the error.
Fixes: 886c8121659d ("mfd: ab8500-debugfs: Remove the racy fiddling with irq_desc")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 660c486590aa ("PCI: dwc: Set 32-bit DMA mask for MSI target address
allocation") added dma_mask_set() call to explicitly set 32-bit DMA mask
for MSI message mapping, but for now it throws a warning on ret == 0, while
dma_set_mask() returns 0 in case of success.
Fix this by inverting the condition.
[bhelgaas: join string to make it greppable]
Fixes: 660c486590aa ("PCI: dwc: Set 32-bit DMA mask for MSI target address allocation")
Link: https://lore.kernel.org/r/20201222150708.67983-1-alobakin@pm.me
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
The clearing of SMT siblings from the SIS mask before checking for an idle
core is a small but unnecessary cost. Defer the clearing of the siblings
until the scan moves to the next potential target. The cost of this was
not measured as it is borderline noise but it should be self-evident.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20201130144020.GS3371@techsingularity.net
clang (quite rightly) complains fairly loudly about the newly added
mpc1_get_mpc_out_mux() function returning an uninitialized value if the
'opp_id' checks don't pass.
This may not happen in practice, but the code really shouldn't return
garbage if the sanity checks don't pass.
So just initialize 'val' to zero to avoid the issue.
Fixes: 110b055b2827 ("drm/amd/display: add getter routine to retrieve mpcc mux")
Cc: Josip Pavic <Josip.Pavic@amd.com>
Cc: Bindu Ramamurthy <bindu.r@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit b9ac0f9dc8ea ("PCI: dwc: Move dw_pcie_setup_rc() to DWC common
code") broke enumeration of downstream devices on Tegra:
In non-working case (next-20201211):
0001:00:00.0 PCI bridge: NVIDIA Corporation Device 1ad2 (rev a1)
0001:01:00.0 SATA controller: Marvell Technology Group Ltd. Device 9171 (rev 13)
0005:00:00.0 PCI bridge: NVIDIA Corporation Device 1ad0 (rev a1)
In working case (v5.10-rc7):
0001:00:00.0 PCI bridge: Molex Incorporated Device 1ad2 (rev a1)
0001:01:00.0 SATA controller: Marvell Technology Group Ltd. Device 9171 (rev 13)
0005:00:00.0 PCI bridge: Molex Incorporated Device 1ad0 (rev a1)
0005:01:00.0 PCI bridge: PLX Technology, Inc. Device 3380 (rev ab)
0005:02:02.0 PCI bridge: PLX Technology, Inc. Device 3380 (rev ab)
0005:03:00.0 USB controller: PLX Technology, Inc. Device 3380 (rev ab)
The problem seems to be dw_pcie_setup_rc() is now called twice before and
after the link up handling. The fix is to move Tegra's link up handling to
.start_link() function like other DWC drivers. Tegra is a bit more
complicated than others as it re-inits the whole DWC controller to retry
the link. With this, the initialization ordering is restored to match the
prior sequence.
Fixes: b9ac0f9dc8ea ("PCI: dwc: Move dw_pcie_setup_rc() to DWC common code")
Link: https://lore.kernel.org/r/20201218143905.1614098-1-robh@kernel.org
Reported-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Tested-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Vidya Sagar <vidyas@nvidia.com>
Kernel-doc requires that a kernel-doc markup to be immediately
below the function prototype, as otherwise it will rename it.
So, move sys_sched_yield() markup to the right place.
Also fix the cpu_util() markup: Kernel-doc markups
should use this format:
identifier - description
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/50cd6f460aeb872ebe518a8e9cfffda2df8bdb0a.1606823973.git.mchehab+huawei@kernel.org
Pull more perf tools updates from Arnaldo Carvalho de Melo:
- Refactor 'perf stat' per CPU/socket/die/thread aggregation fixing use
cases in ARM machines.
- Fix memory leak when synthesizing SDT probes in 'perf probe'.
- Update kernel header copies related to KVM, epol_pwait. msr-index and
powerpc and s390 syscall tables.
* tag 'perf-tools-2020-12-24' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (24 commits)
perf probe: Fix memory leak when synthesizing SDT probes
perf stat aggregation: Add separate thread member
perf stat aggregation: Add separate core member
perf stat aggregation: Add separate die member
perf stat aggregation: Add separate socket member
perf stat aggregation: Add separate node member
perf stat aggregation: Start using cpu_aggr_id in map
perf cpumap: Drop in cpu_aggr_map struct
perf cpumap: Add new map type for aggregation
perf stat: Replace aggregation ID with a struct
perf cpumap: Add new struct for cpu aggregation
perf cpumap: Use existing allocator to avoid using malloc
perf tests: Improve topology test to check all aggregation types
perf tools: Update s390's syscall.tbl copy from the kernel sources
perf tools: Update powerpc's syscall.tbl copy from the kernel sources
perf s390: Move syscall.tbl check into check-headers.sh
perf powerpc: Move syscall.tbl check to check-headers.sh
tools headers UAPI: Synch KVM's svm.h header with the kernel
tools kvm headers: Update KVM headers from the kernel sources
tools headers UAPI: Sync KVM's vmx.h header with the kernel sources
...
- Add PCI endpoint subsystem references to MAINTAINERS (Gustavo Pimentel)
* remotes/lorenzo/pci/misc:
MAINTAINERS: Add missing documentation references to PCI Endpoint Subsystem
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