11 Jun, 2020
1 commit
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That code is already not traceable. Move it into the noinstr section so the
objtool section validation does not trigger.Annotate the warning code as "safe". While it might be not under all
circumstances, getting the information out is important enough.Should this ever trigger from the sensitive code which is shielded against
instrumentation, e.g. low level entry, then the printk is the least of the
worries.Addresses the objtool warnings:
vmlinux.o: warning: objtool: context_tracking_recursion_enter()+0x7: call to __this_cpu_preempt_check() leaves .noinstr.text section
vmlinux.o: warning: objtool: __context_tracking_exit()+0x17: call to __this_cpu_preempt_check() leaves .noinstr.text section
vmlinux.o: warning: objtool: __context_tracking_enter()+0x2a: call to __this_cpu_preempt_check() leaves .noinstr.text sectionSigned-off-by: Thomas Gleixner
Reviewed-by: Alexandre Chartre
Acked-by: Peter Zijlstra
Link: https://lkml.kernel.org/r/20200505134340.902709267@linutronix.de
09 Oct, 2019
1 commit
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The check_preemption_disabled() function uses cpumask_equal() to see
if the task is bounded to the current CPU only. cpumask_equal() calls
memcmp() to do the comparison. As x86 doesn't have __HAVE_ARCH_MEMCMP,
the slow memcmp() function in lib/string.c is used.On a RT kernel that call check_preemption_disabled() very frequently,
below is the perf-record output of a certain microbenchmark:42.75% 2.45% testpmd [kernel.kallsyms] [k] check_preemption_disabled
40.01% 39.97% testpmd [kernel.kallsyms] [k] memcmpWe should avoid calling memcmp() in performance critical path. So the
cpumask_equal() call is now replaced with an equivalent simpler check.Signed-off-by: Waiman Long
Signed-off-by: Peter Zijlstra (Intel)
Reviewed-by: Juri Lelli
Acked-by: Sebastian Andrzej Siewior
Cc: Linus Torvalds
Cc: Masami Hiramatsu
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: https://lkml.kernel.org/r/20191003203608.21881-1-longman@redhat.com
Signed-off-by: Ingo Molnar
03 Jun, 2019
1 commit
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In commit:
4b53a3412d66 ("sched/core: Remove the tsk_nr_cpus_allowed() wrapper")
the tsk_nr_cpus_allowed() wrapper was removed. There was not
much difference in !RT but in RT we used this to implement
migrate_disable(). Within a migrate_disable() section the CPU mask is
restricted to single CPU while the "normal" CPU mask remains untouched.As an alternative implementation Ingo suggested to use:
struct task_struct {
const cpumask_t *cpus_ptr;
cpumask_t cpus_mask;
};
with
t->cpus_ptr = &t->cpus_mask;In -RT we then can switch the cpus_ptr to:
t->cpus_ptr = &cpumask_of(task_cpu(p));
in a migration disabled region. The rules are simple:
- Code that 'uses' ->cpus_allowed would use the pointer.
- Code that 'modifies' ->cpus_allowed would use the direct mask.Signed-off-by: Sebastian Andrzej Siewior
Signed-off-by: Peter Zijlstra (Intel)
Reviewed-by: Thomas Gleixner
Cc: Linus Torvalds
Cc: Peter Zijlstra
Link: https://lkml.kernel.org/r/20190423142636.14347-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar
13 Feb, 2019
1 commit
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Since kprobes depends on preempt disable/enable, probing
on the preempt debug routines can cause recursive breakpoint
bugs.Signed-off-by: Masami Hiramatsu
Cc: Alexander Shishkin
Cc: Andrea Righi
Cc: Arnaldo Carvalho de Melo
Cc: Jiri Olsa
Cc: Linus Torvalds
Cc: Mathieu Desnoyers
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/154998804911.31052.3541963527929117920.stgit@devbox
Signed-off-by: Ingo Molnar
05 Jan, 2018
1 commit
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print_symbol() is a very old API that has been obsoleted by %pS format
specifier in a normal printk() call.Replace print_symbol() with a direct printk("%pS") call.
Link: http://lkml.kernel.org/r/20171211125025.2270-13-sergey.senozhatsky@gmail.com
To: Andrew Morton
To: Russell King
To: Catalin Marinas
To: Mark Salter
To: Tony Luck
To: David Howells
To: Yoshinori Sato
To: Guan Xuetao
To: Borislav Petkov
To: Greg Kroah-Hartman
To: Thomas Gleixner
To: Peter Zijlstra
To: Vineet Gupta
To: Fengguang Wu
Cc: Steven Rostedt
Cc: Petr Mladek
Cc: LKML
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-sh@vger.kernel.org
Cc: linux-edac@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Sergey Senozhatsky
[pmladek@suse.com: updated commit message]
Signed-off-by: Petr Mladek
02 Nov, 2017
1 commit
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
23 May, 2017
1 commit
-
might_sleep() and smp_processor_id() checks are enabled after the boot
process is done. That hides bugs in the SMP bringup and driver
initialization code.Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.Tested-by: Mark Rutland
Signed-off-by: Thomas Gleixner
Signed-off-by: Peter Zijlstra (Intel)
Acked-by: Mark Rutland
Cc: Greg Kroah-Hartman
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Steven Rostedt
Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de
Signed-off-by: Ingo Molnar
02 Mar, 2017
1 commit
-
So the original intention of tsk_cpus_allowed() was to 'future-proof'
the field - but it's pretty ineffectual at that, because half of
the code uses ->cpus_allowed directly ...Also, the wrapper makes the code longer than the original expression!
So just get rid of it. This also shrinks a bit.
Acked-by: Linus Torvalds
Cc: Mike Galbraith
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar
08 Apr, 2014
1 commit
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We define a check function in order to avoid trouble with the include
files. Then the higher level __this_cpu macros are modified to invoke
the preemption check.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Christoph Lameter
Acked-by: Ingo Molnar
Cc: Tejun Heo
Tested-by: Grygorii Strashko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Sep, 2013
1 commit
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Replace the single preempt_count() 'function' that's an lvalue with
two proper functions:preempt_count() - returns the preempt_count value as rvalue
preempt_count_set() - Allows setting the preempt-count valueAlso provide preempt_count_ptr() as a convenience wrapper to implement
all modifying operations.Signed-off-by: Peter Zijlstra
Link: http://lkml.kernel.org/n/tip-orxrbycjozopqfhb4dxdkdvb@git.kernel.org
[ Fixed build failure. ]
Signed-off-by: Ingo Molnar
08 Mar, 2012
1 commit
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For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.Signed-off-by: Paul Gortmaker
06 Oct, 2011
1 commit
-
This task is preparatory for the migrate_disable() implementation, but
stands on its own and provides a cleanup.It currently only converts those sites required for task-placement.
Kosaki-san once mentioned replacing cpus_allowed with a proper
cpumask_t instead of the NR_CPUS sized array it currently is, that
would also require something like this.Signed-off-by: Peter Zijlstra
Acked-by: Thomas Gleixner
Cc: KOSAKI Motohiro
Link: http://lkml.kernel.org/n/tip-e42skvaddos99psip0vce41o@git.kernel.org
Signed-off-by: Ingo Molnar
30 Jan, 2009
1 commit
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Impact: fix debug_smp_processor_id() for CONFIG_CPUMASK_OFFSTACK=y
The scheduler now uses the new cpumask API, which deals up to
nr_cpumask_bits, whereas the API used NR_CPUS bits.If CONFIG_CPUMASK_OFFSTACK=y these two are not equal, so the top bits
are undefined. Leading to bug 12518 "BUG: using smp_processor_id() in
preemptible [00000000] code: dellWirelessCtl/..."The fix is simple: use the modern API in the check.
Signed-off-by: Rusty Russell
Signed-off-by: Mike Travis
Signed-off-by: Ingo Molnar
26 Jul, 2008
1 commit
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* Replace previous instances of the cpumask_of_cpu_ptr* macros
with a the new (lvalue capable) generic cpumask_of_cpu().Signed-off-by: Mike Travis
Cc: Andrew Morton
Cc: Jack Steiner
Cc: Rusty Russell
Signed-off-by: Ingo Molnar
19 Jul, 2008
2 commits
-
fix typo.
Signed-off-by: Ingo Molnar
-
* Optimize various places where a pointer to the cpumask_of_cpu value
will result in reducing stack pressure.Signed-off-by: Mike Travis
Signed-off-by: Ingo Molnar
24 May, 2008
2 commits
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The debug smp_processor_id caused a recursive fault in debugging
the irqsoff tracer. The tracer used a smp_processor_id in the
ftrace callback, and this function called preempt_disable which
also is traced. This caused a recursive fault (stack overload).Since using smp_processor_id without debugging on does not cause
faults with the tracer (even when the tracer is wrong), the
debug version should not cause a system reboot.This changes the debug_smp_processor_id to use the notrace versions
of preempt_disable and enable.Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner -
Mark with "notrace" functions in core code that should not be
traced. The "notrace" attribute will prevent gcc from adding
a call to ftrace on the annotated funtions.Signed-off-by: Arnaldo Carvalho de Melo
Signed-off-by: Steven Rostedt
Signed-off-by: Ingo Molnar
Signed-off-by: Thomas Gleixner
07 Feb, 2008
1 commit
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- Account for debug_smp_processor_id()'s own preempt_disable() when
displaying the preempt_count().- 80 cols, not 800.
Cc: Ingo Molnar
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
31 Oct, 2005
1 commit
-
I recently picked up my older work to remove unnecessary #includes of
sched.h, starting from a patch by Dave Jones to not include sched.h
from module.h. This reduces the number of indirect includes of sched.h
by ~300. Another ~400 pointless direct includes can be removed after
this disentangling (patch to follow later).
However, quite a few indirect includes need to be fixed up for this.In order to feed the patches through -mm with as little disturbance as
possible, I've split out the fixes I accumulated up to now (complete for
i386 and x86_64, more archs to follow later) and post them before the real
patch. This way this large part of the patch is kept simple with only
adding #includes, and all hunks are independent of each other. So if any
hunk rejects or gets in the way of other patches, just drop it. My scripts
will pick it up again in the next round.Signed-off-by: Tim Schmielau
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Jun, 2005
1 commit
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This patch implements a number of smp_processor_id() cleanup ideas that
Arjan van de Ven and I came up with.The previous __smp_processor_id/_smp_processor_id/smp_processor_id API
spaghetti was hard to follow both on the implementational and on the
usage side.Some of the complexity arose from picking wrong names, some of the
complexity comes from the fact that not all architectures defined
__smp_processor_id.In the new code, there are two externally visible symbols:
- smp_processor_id(): debug variant.
- raw_smp_processor_id(): nondebug variant. Replaces all existing
uses of _smp_processor_id() and __smp_processor_id(). Defined
by every SMP architecture in include/asm-*/smp.h.There is one new internal symbol, dependent on DEBUG_PREEMPT:
- debug_smp_processor_id(): internal debug variant, mapped to
smp_processor_id().Also, i moved debug_smp_processor_id() from lib/kernel_lock.c into a new
lib/smp_processor_id.c file. All related comments got updated and/or
clarified.I have build/boot tested the following 8 .config combinations on x86:
{SMP,UP} x {PREEMPT,!PREEMPT} x {DEBUG_PREEMPT,!DEBUG_PREEMPT}
I have also build/boot tested x64 on UP/PREEMPT/DEBUG_PREEMPT. (Other
architectures are untested, but should work just fine.)Signed-off-by: Ingo Molnar
Signed-off-by: Arjan van de Ven
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds