<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/alpha/kernel/time.c, branch v6.6.131</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>alpha: Replace setup_irq() by request_irq()</title>
<updated>2020-03-29T19:03:41+00:00</updated>
<author>
<name>afzal mohammed</name>
<email>afzal.mohd.ma@gmail.com</email>
</author>
<published>2020-03-27T16:09:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=82c849eb36fe6dcfa955b25c7aad71b5c1b4403c'/>
<id>82c849eb36fe6dcfa955b25c7aad71b5c1b4403c</id>
<content type='text'>
request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

setup_irq() was required in older kernels as the memory allocator was not
available during early boot.

Hence replace setup_irq() by request_irq().

Signed-off-by: afzal mohammed &lt;afzal.mohd.ma@gmail.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: Matt Turner &lt;mattst88@gmail.com&gt;
Link: https://lkml.kernel.org/r/51f8ae7da9f47a23596388141933efa2bdef317b.1585320721.git.afzal.mohd.ma@gmail.com

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

setup_irq() was required in older kernels as the memory allocator was not
available during early boot.

Hence replace setup_irq() by request_irq().

Signed-off-by: afzal mohammed &lt;afzal.mohd.ma@gmail.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: Matt Turner &lt;mattst88@gmail.com&gt;
Link: https://lkml.kernel.org/r/51f8ae7da9f47a23596388141933efa2bdef317b.1585320721.git.afzal.mohd.ma@gmail.com

</pre>
</div>
</content>
</entry>
<entry>
<title>License cleanup: add SPDX GPL-2.0 license identifier to files with no license</title>
<updated>2017-11-02T10:10:55+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2017-11-01T14:07:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b24413180f5600bcb3bb70fbed5cf186b60864bd'/>
<id>b24413180f5600bcb3bb70fbed5cf186b60864bd</id>
<content type='text'>
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 &amp; 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 &gt;5
   lines of source
 - File already had some variant of a license header in it (even if &lt;5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart &lt;kstewart@linuxfoundation.org&gt;
Reviewed-by: Philippe Ombredanne &lt;pombredanne@nexb.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
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 &amp; 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 &gt;5
   lines of source
 - File already had some variant of a license header in it (even if &lt;5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart &lt;kstewart@linuxfoundation.org&gt;
Reviewed-by: Philippe Ombredanne &lt;pombredanne@nexb.com&gt;
Reviewed-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource: Use a plain u64 instead of cycle_t</title>
<updated>2016-12-25T10:04:12+00:00</updated>
<author>
<name>Thomas Gleixner</name>
<email>tglx@linutronix.de</email>
</author>
<published>2016-12-21T19:32:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=a5a1d1c2914b5316924c7893eb683a5420ebd3be'/>
<id>a5a1d1c2914b5316924c7893eb683a5420ebd3be</id>
<content type='text'>
There is no point in having an extra type for extra confusion. u64 is
unambiguous.

Conversion was done with the following coccinelle script:

@rem@
@@
-typedef u64 cycle_t;

@fix@
typedef cycle_t;
@@
-cycle_t
+u64

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: John Stultz &lt;john.stultz@linaro.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is no point in having an extra type for extra confusion. u64 is
unambiguous.

Conversion was done with the following coccinelle script:

@rem@
@@
-typedef u64 cycle_t;

@fix@
typedef cycle_t;
@@
-cycle_t
+u64

Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: John Stultz &lt;john.stultz@linaro.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Replace &lt;asm/uaccess.h&gt; with &lt;linux/uaccess.h&gt; globally</title>
<updated>2016-12-24T19:46:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-12-24T19:46:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=7c0f6ba682b9c7632072ffbedf8d328c8f3c42ba'/>
<id>7c0f6ba682b9c7632072ffbedf8d328c8f3c42ba</id>
<content type='text'>
This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*&lt;asm/uaccess.h&gt;'
  sed -i -e "s!$PATT!#include &lt;linux/uaccess.h&gt;!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*&lt;asm/uaccess.h&gt;'
  sed -i -e "s!$PATT!#include &lt;linux/uaccess.h&gt;!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha/time: Migrate to new 'set-state' interface</title>
<updated>2015-08-10T09:40:58+00:00</updated>
<author>
<name>Viresh Kumar</name>
<email>viresh.kumar@linaro.org</email>
</author>
<published>2015-07-16T11:26:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=6ec81932988b231e3038f7b73d58b2f9ce1e7ab0'/>
<id>6ec81932988b231e3038f7b73d58b2f9ce1e7ab0</id>
<content type='text'>
Migrate alpha driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.

This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.

rtc clockevent device wasn't doing anything in set-mode and so its
set-state callbacks aren't implemented.

Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Migrate alpha driver to the new 'set-state' interface provided by
clockevents core, the earlier 'set-mode' interface is marked obsolete
now.

This also enables us to implement callbacks for new states of clockevent
devices, for example: ONESHOT_STOPPED.

rtc clockevent device wasn't doing anything in set-mode and so its
set-state callbacks aren't implemented.

Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Christoph Lameter &lt;cl@linux.com&gt;
Cc: linux-alpha@vger.kernel.org
Signed-off-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha: Replace __get_cpu_var</title>
<updated>2014-08-26T17:45:53+00:00</updated>
<author>
<name>Christoph Lameter</name>
<email>cl@linux.com</email>
</author>
<published>2014-08-17T17:30:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=2999a4b354c24985268f9310bc9522ff358453a8'/>
<id>2999a4b354c24985268f9310bc9522ff358453a8</id>
<content type='text'>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &amp;__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&amp;(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &amp;__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&amp;y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&amp;x, this_cpu_ptr(&amp;y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

CC: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Acked-by: Richard Henderson &lt;rth@twiddle.net&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &amp;__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&amp;(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &amp;__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&amp;y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&amp;x, this_cpu_ptr(&amp;y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

CC: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Acked-by: Richard Henderson &lt;rth@twiddle.net&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha: Use qemu+cserve provided high-res clock and alarm.</title>
<updated>2013-11-17T00:33:21+00:00</updated>
<author>
<name>Richard Henderson</name>
<email>rth@twiddle.net</email>
</author>
<published>2013-07-14T21:50:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=4914d7b458e35a7db2f9c7dc6eb014620254bbbf'/>
<id>4914d7b458e35a7db2f9c7dc6eb014620254bbbf</id>
<content type='text'>
QEMU provides a high-resolution timer and alarm; use this for
a clock source and clock event source when available.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
QEMU provides a high-resolution timer and alarm; use this for
a clock source and clock event source when available.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha: Switch to GENERIC_CLOCKEVENTS</title>
<updated>2013-11-17T00:33:19+00:00</updated>
<author>
<name>Richard Henderson</name>
<email>rth@twiddle.net</email>
</author>
<published>2013-07-14T17:57:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=a1659d6d128a7e0c2985bce7c957b66af1f71181'/>
<id>a1659d6d128a7e0c2985bce7c957b66af1f71181</id>
<content type='text'>
This allows us to get rid of some hacky code for SMP.  Get rid of
some cycle counter hackery that's now handled by generic code via
clocksource + clock_event_device objects.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This allows us to get rid of some hacky code for SMP.  Get rid of
some cycle counter hackery that's now handled by generic code via
clocksource + clock_event_device objects.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha: Enable the rpcc clocksource for single processor</title>
<updated>2013-11-17T00:33:18+00:00</updated>
<author>
<name>Richard Henderson</name>
<email>rth@twiddle.net</email>
</author>
<published>2013-07-14T16:55:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=db2d3260617ae8c9076ef12e6de06bd5b3d82cd3'/>
<id>db2d3260617ae8c9076ef12e6de06bd5b3d82cd3</id>
<content type='text'>
Don't depend on SMP, just check the number of processors online.
This allows a single distribution kernel to use the clocksource
when run on a single processor machine.  Do depend on whether or
not we're using WTINT.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Don't depend on SMP, just check the number of processors online.
This allows a single distribution kernel to use the clocksource
when run on a single processor machine.  Do depend on whether or
not we're using WTINT.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>alpha: Reorganize rtc handling</title>
<updated>2013-11-17T00:33:16+00:00</updated>
<author>
<name>Richard Henderson</name>
<email>rth@twiddle.net</email>
</author>
<published>2013-07-13T22:49:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=85d0b3a573d8b711ee0c96199ac24a0f3283ed68'/>
<id>85d0b3a573d8b711ee0c96199ac24a0f3283ed68</id>
<content type='text'>
Discontinue use of GENERIC_CMOS_UPDATE; rely on the RTC subsystem.

The marvel platform requires that the rtc only be touched from the
boot cpu.  This had been partially implemented with hooks for
get/set_rtc_time, but read/update_persistent_clock were not handled.
Move the hooks from the machine_vec to a special rtc_class_ops struct.

We had read_persistent_clock managing the epoch against which the
rtc hw is based, but this didn't apply to get_rtc_time or set_rtc_time.
This resulted in incorrect values when hwclock(8) gets involved.

Allow the epoch to be set from the kernel command-line, overriding
the autodetection, which is doomed to fail in 2020.  Further, by
implementing the rtc ioctl function, we can expose this epoch to
userland.

Elide the alarm functions that RTC_DRV_CMOS implements.  This was
highly questionable on Alpha, since the interrupt is used by the
system timer.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Discontinue use of GENERIC_CMOS_UPDATE; rely on the RTC subsystem.

The marvel platform requires that the rtc only be touched from the
boot cpu.  This had been partially implemented with hooks for
get/set_rtc_time, but read/update_persistent_clock were not handled.
Move the hooks from the machine_vec to a special rtc_class_ops struct.

We had read_persistent_clock managing the epoch against which the
rtc hw is based, but this didn't apply to get_rtc_time or set_rtc_time.
This resulted in incorrect values when hwclock(8) gets involved.

Allow the epoch to be set from the kernel command-line, overriding
the autodetection, which is doomed to fail in 2020.  Further, by
implementing the rtc ioctl function, we can expose this epoch to
userland.

Elide the alarm functions that RTC_DRV_CMOS implements.  This was
highly questionable on Alpha, since the interrupt is used by the
system timer.

Signed-off-by: Richard Henderson &lt;rth@twiddle.net&gt;
</pre>
</div>
</content>
</entry>
</feed>
