<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/lib/math, branch v6.12.80</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>Merge tag 'mm-nonmm-stable-2024-09-21-07-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2024-09-21T15:20:50+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-21T15:20:50+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=7856a565416e0cf091f825b0e25c7a1b7abb650e'/>
<id>7856a565416e0cf091f825b0e25c7a1b7abb650e</id>
<content type='text'>
Pull non-MM updates from Andrew Morton:
 "Many singleton patches - please see the various changelogs for
  details.

  Quite a lot of nilfs2 work this time around.

  Notable patch series in this pull request are:

   - "mul_u64_u64_div_u64: new implementation" by Nicolas Pitre, with
     assistance from Uwe Kleine-König. Reimplement mul_u64_u64_div_u64()
     to provide (much) more accurate results. The current implementation
     was causing Uwe some issues in the PWM drivers.

   - "xz: Updates to license, filters, and compression options" from
     Lasse Collin. Miscellaneous maintenance and kinor feature work to
     the xz decompressor.

   - "Fix some GDB command error and add some GDB commands" from
     Kuan-Ying Lee. Fixes and enhancements to the gdb scripts.

   - "treewide: add missing MODULE_DESCRIPTION() macros" from Jeff
     Johnson. Adds lots of MODULE_DESCRIPTIONs, thus fixing lots of
     warnings about this.

   - "nilfs2: add support for some common ioctls" from Ryusuke Konishi.
     Adds various commonly-available ioctls to nilfs2.

   - "This series fixes a number of formatting issues in kernel doc
     comments" from Ryusuke Konishi does that.

   - "nilfs2: prevent unexpected ENOENT propagation" from Ryusuke
     Konishi. Fix issues where -ENOENT was being unintentionally and
     inappropriately returned to userspace.

   - "nilfs2: assorted cleanups" from Huang Xiaojia.

   - "nilfs2: fix potential issues with empty b-tree nodes" from Ryusuke
     Konishi fixes some issues which can occur on corrupted nilfs2
     filesystems.

   - "scripts/decode_stacktrace.sh: improve error reporting and
     usability" from Luca Ceresoli does those things"

* tag 'mm-nonmm-stable-2024-09-21-07-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (103 commits)
  list: test: increase coverage of list_test_list_replace*()
  list: test: fix tests for list_cut_position()
  proc: use __auto_type more
  treewide: correct the typo 'retun'
  ocfs2: cleanup return value and mlog in ocfs2_global_read_info()
  nilfs2: remove duplicate 'unlikely()' usage
  nilfs2: fix potential oob read in nilfs_btree_check_delete()
  nilfs2: determine empty node blocks as corrupted
  nilfs2: fix potential null-ptr-deref in nilfs_btree_insert()
  user_namespace: use kmemdup_array() instead of kmemdup() for multiple allocation
  tools/mm: rm thp_swap_allocator_test when make clean
  squashfs: fix percpu address space issues in decompressor_multi_percpu.c
  lib: glob.c: added null check for character class
  nilfs2: refactor nilfs_segctor_thread()
  nilfs2: use kthread_create and kthread_stop for the log writer thread
  nilfs2: remove sc_timer_task
  nilfs2: do not repair reserved inode bitmap in nilfs_new_inode()
  nilfs2: eliminate the shared counter and spinlock for i_generation
  nilfs2: separate inode type information from i_state field
  nilfs2: use the BITS_PER_LONG macro
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull non-MM updates from Andrew Morton:
 "Many singleton patches - please see the various changelogs for
  details.

  Quite a lot of nilfs2 work this time around.

  Notable patch series in this pull request are:

   - "mul_u64_u64_div_u64: new implementation" by Nicolas Pitre, with
     assistance from Uwe Kleine-König. Reimplement mul_u64_u64_div_u64()
     to provide (much) more accurate results. The current implementation
     was causing Uwe some issues in the PWM drivers.

   - "xz: Updates to license, filters, and compression options" from
     Lasse Collin. Miscellaneous maintenance and kinor feature work to
     the xz decompressor.

   - "Fix some GDB command error and add some GDB commands" from
     Kuan-Ying Lee. Fixes and enhancements to the gdb scripts.

   - "treewide: add missing MODULE_DESCRIPTION() macros" from Jeff
     Johnson. Adds lots of MODULE_DESCRIPTIONs, thus fixing lots of
     warnings about this.

   - "nilfs2: add support for some common ioctls" from Ryusuke Konishi.
     Adds various commonly-available ioctls to nilfs2.

   - "This series fixes a number of formatting issues in kernel doc
     comments" from Ryusuke Konishi does that.

   - "nilfs2: prevent unexpected ENOENT propagation" from Ryusuke
     Konishi. Fix issues where -ENOENT was being unintentionally and
     inappropriately returned to userspace.

   - "nilfs2: assorted cleanups" from Huang Xiaojia.

   - "nilfs2: fix potential issues with empty b-tree nodes" from Ryusuke
     Konishi fixes some issues which can occur on corrupted nilfs2
     filesystems.

   - "scripts/decode_stacktrace.sh: improve error reporting and
     usability" from Luca Ceresoli does those things"

* tag 'mm-nonmm-stable-2024-09-21-07-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (103 commits)
  list: test: increase coverage of list_test_list_replace*()
  list: test: fix tests for list_cut_position()
  proc: use __auto_type more
  treewide: correct the typo 'retun'
  ocfs2: cleanup return value and mlog in ocfs2_global_read_info()
  nilfs2: remove duplicate 'unlikely()' usage
  nilfs2: fix potential oob read in nilfs_btree_check_delete()
  nilfs2: determine empty node blocks as corrupted
  nilfs2: fix potential null-ptr-deref in nilfs_btree_insert()
  user_namespace: use kmemdup_array() instead of kmemdup() for multiple allocation
  tools/mm: rm thp_swap_allocator_test when make clean
  squashfs: fix percpu address space issues in decompressor_multi_percpu.c
  lib: glob.c: added null check for character class
  nilfs2: refactor nilfs_segctor_thread()
  nilfs2: use kthread_create and kthread_stop for the log writer thread
  nilfs2: remove sc_timer_task
  nilfs2: do not repair reserved inode bitmap in nilfs_new_inode()
  nilfs2: eliminate the shared counter and spinlock for i_generation
  nilfs2: separate inode type information from i_state field
  nilfs2: use the BITS_PER_LONG macro
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>lib/math: Add int_pow test suite</title>
<updated>2024-09-12T16:03:00+00:00</updated>
<author>
<name>Luis Felipe Hernandez</name>
<email>luis.hernandez093@gmail.com</email>
</author>
<published>2024-09-10T01:10:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=7fcc9b53216cd87f73cc6dbb404220350ddc93b8'/>
<id>7fcc9b53216cd87f73cc6dbb404220350ddc93b8</id>
<content type='text'>
Adds test suite for integer based power function which performs integer
exponentiation.

The test suite is designed to verify that the implementation of int_pow
correctly computes the power of a given base raised to a given exponent.

The tests check various scenarios and edge cases to ensure the accuracy
and reliability of the exponentiation function.

Updated commit with test information at commit time: Shuah Khan

Signed-off-by: Luis Felipe Hernandez &lt;luis.hernandez093@gmail.com&gt;
Reviewed-by: David Gow &lt;davidgow@google.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Adds test suite for integer based power function which performs integer
exponentiation.

The test suite is designed to verify that the implementation of int_pow
correctly computes the power of a given base raised to a given exponent.

The tests check various scenarios and edge cases to ensure the accuracy
and reliability of the exponentiation function.

Updated commit with test information at commit time: Shuah Khan

Signed-off-by: Luis Felipe Hernandez &lt;luis.hernandez093@gmail.com&gt;
Reviewed-by: David Gow &lt;davidgow@google.com&gt;
Signed-off-by: Shuah Khan &lt;skhan@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mul_u64_u64_div_u64: basic sanity test</title>
<updated>2024-09-02T03:43:22+00:00</updated>
<author>
<name>Nicolas Pitre</name>
<email>npitre@baylibre.com</email>
</author>
<published>2024-07-07T19:05:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=1635e62e75a7bbb1c6274f6b43911cedfe0da60a'/>
<id>1635e62e75a7bbb1c6274f6b43911cedfe0da60a</id>
<content type='text'>
Verify that edge cases produce proper results, and some more.

[npitre@baylibre.com: avoid undefined shift value]
  Link: https://lkml.kernel.org/r/7rrs9pn1-n266-3013-9q6n-1osp8r8s0rrn@syhkavp.arg
Link: https://lkml.kernel.org/r/20240707190648.1982714-3-nico@fluxnic.net
Signed-off-by: Nicolas Pitre &lt;npitre@baylibre.com&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Cc: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Verify that edge cases produce proper results, and some more.

[npitre@baylibre.com: avoid undefined shift value]
  Link: https://lkml.kernel.org/r/7rrs9pn1-n266-3013-9q6n-1osp8r8s0rrn@syhkavp.arg
Link: https://lkml.kernel.org/r/20240707190648.1982714-3-nico@fluxnic.net
Signed-off-by: Nicolas Pitre &lt;npitre@baylibre.com&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Cc: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mul_u64_u64_div_u64: make it precise always</title>
<updated>2024-09-02T03:43:22+00:00</updated>
<author>
<name>Nicolas Pitre</name>
<email>npitre@baylibre.com</email>
</author>
<published>2024-07-07T19:05:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b29a62d87cc0af3e9d134e9e0863b2cb053070b8'/>
<id>b29a62d87cc0af3e9d134e9e0863b2cb053070b8</id>
<content type='text'>
Patch series "mul_u64_u64_div_u64: new implementation", v3.

This provides an implementation for mul_u64_u64_div_u64() that always
produces exact results.


This patch (of 2):

Library facilities must always return exact results.  If the caller may be
contented with approximations then it should do the approximation on its
own.

In this particular case the comment in the code says "the algorithm
... below might lose some precision". Well, if you try it with e.g.:

	a = 18446462598732840960
	b = 18446462598732840960
	c = 18446462598732840961

then the produced answer is 0 whereas the exact answer should be
18446462598732840959.  This is _some_ precision lost indeed!

Let's reimplement this function so it always produces the exact result
regardless of its inputs while preserving existing fast paths when
possible.

Uwe said:

: My personal interest is to get the calculations in pwm drivers right. 
: This function is used in several drivers below drivers/pwm/ .  With the
: errors in mul_u64_u64_div_u64(), pwm consumers might not get the
: settings they request.  Although I have to admit that I'm not aware it
: breaks real use cases (because typically the periods used are too short
: to make the involved multiplications overflow), but I pretty sure am
: not aware of all usages and it breaks testing.
: 
: Another justification is commits like
: https://git.kernel.org/tip/77baa5bafcbe1b2a15ef9c37232c21279c95481c,
: where people start to work around the precision shortcomings of
: mul_u64_u64_div_u64().

Link: https://lkml.kernel.org/r/20240707190648.1982714-1-nico@fluxnic.net
Link: https://lkml.kernel.org/r/20240707190648.1982714-2-nico@fluxnic.net
Signed-off-by: Nicolas Pitre &lt;npitre@baylibre.com&gt;
Tested-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Tested-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mul_u64_u64_div_u64: new implementation", v3.

This provides an implementation for mul_u64_u64_div_u64() that always
produces exact results.


This patch (of 2):

Library facilities must always return exact results.  If the caller may be
contented with approximations then it should do the approximation on its
own.

In this particular case the comment in the code says "the algorithm
... below might lose some precision". Well, if you try it with e.g.:

	a = 18446462598732840960
	b = 18446462598732840960
	c = 18446462598732840961

then the produced answer is 0 whereas the exact answer should be
18446462598732840959.  This is _some_ precision lost indeed!

Let's reimplement this function so it always produces the exact result
regardless of its inputs while preserving existing fast paths when
possible.

Uwe said:

: My personal interest is to get the calculations in pwm drivers right. 
: This function is used in several drivers below drivers/pwm/ .  With the
: errors in mul_u64_u64_div_u64(), pwm consumers might not get the
: settings they request.  Although I have to admit that I'm not aware it
: breaks real use cases (because typically the periods used are too short
: to make the involved multiplications overflow), but I pretty sure am
: not aware of all usages and it breaks testing.
: 
: Another justification is commits like
: https://git.kernel.org/tip/77baa5bafcbe1b2a15ef9c37232c21279c95481c,
: where people start to work around the precision shortcomings of
: mul_u64_u64_div_u64().

Link: https://lkml.kernel.org/r/20240707190648.1982714-1-nico@fluxnic.net
Link: https://lkml.kernel.org/r/20240707190648.1982714-2-nico@fluxnic.net
Signed-off-by: Nicolas Pitre &lt;npitre@baylibre.com&gt;
Tested-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Reviewed-by: Uwe Kleine-König &lt;u.kleine-koenig@baylibre.com&gt;
Tested-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2024-07-22T00:56:22+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-07-22T00:56:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=527eff227d4321c6ea453db1083bc4fdd4d3a3e8'/>
<id>527eff227d4321c6ea453db1083bc4fdd4d3a3e8</id>
<content type='text'>
Pull non-MM updates from Andrew Morton:

 - In the series "treewide: Refactor heap related implementation",
   Kuan-Wei Chiu has significantly reworked the min_heap library code
   and has taught bcachefs to use the new more generic implementation.

 - Yury Norov's series "Cleanup cpumask.h inclusion in core headers"
   reworks the cpumask and nodemask headers to make things generally
   more rational.

 - Kuan-Wei Chiu has sent along some maintenance work against our
   sorting library code in the series "lib/sort: Optimizations and
   cleanups".

 - More library maintainance work from Christophe Jaillet in the series
   "Remove usage of the deprecated ida_simple_xx() API".

 - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the
   series "nilfs2: eliminate the call to inode_attach_wb()".

 - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix
   GDB command error".

 - Plus the usual shower of singleton patches all over the place. Please
   see the relevant changelogs for details.

* tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits)
  ia64: scrub ia64 from poison.h
  watchdog/perf: properly initialize the turbo mode timestamp and rearm counter
  tsacct: replace strncpy() with strscpy()
  lib/bch.c: use swap() to improve code
  test_bpf: convert comma to semicolon
  init/modpost: conditionally check section mismatch to __meminit*
  init: remove unused __MEMINIT* macros
  nilfs2: Constify struct kobj_type
  nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro
  math: rational: add missing MODULE_DESCRIPTION() macro
  lib/zlib: add missing MODULE_DESCRIPTION() macro
  fs: ufs: add MODULE_DESCRIPTION()
  lib/rbtree.c: fix the example typo
  ocfs2: add bounds checking to ocfs2_check_dir_entry()
  fs: add kernel-doc comments to ocfs2_prepare_orphan_dir()
  coredump: simplify zap_process()
  selftests/fpu: add missing MODULE_DESCRIPTION() macro
  compiler.h: simplify data_race() macro
  build-id: require program headers to be right after ELF header
  resource: add missing MODULE_DESCRIPTION()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull non-MM updates from Andrew Morton:

 - In the series "treewide: Refactor heap related implementation",
   Kuan-Wei Chiu has significantly reworked the min_heap library code
   and has taught bcachefs to use the new more generic implementation.

 - Yury Norov's series "Cleanup cpumask.h inclusion in core headers"
   reworks the cpumask and nodemask headers to make things generally
   more rational.

 - Kuan-Wei Chiu has sent along some maintenance work against our
   sorting library code in the series "lib/sort: Optimizations and
   cleanups".

 - More library maintainance work from Christophe Jaillet in the series
   "Remove usage of the deprecated ida_simple_xx() API".

 - Ryusuke Konishi continues with the nilfs2 fixes and clanups in the
   series "nilfs2: eliminate the call to inode_attach_wb()".

 - Kuan-Ying Lee has some fixes to the gdb scripts in the series "Fix
   GDB command error".

 - Plus the usual shower of singleton patches all over the place. Please
   see the relevant changelogs for details.

* tag 'mm-nonmm-stable-2024-07-21-15-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (98 commits)
  ia64: scrub ia64 from poison.h
  watchdog/perf: properly initialize the turbo mode timestamp and rearm counter
  tsacct: replace strncpy() with strscpy()
  lib/bch.c: use swap() to improve code
  test_bpf: convert comma to semicolon
  init/modpost: conditionally check section mismatch to __meminit*
  init: remove unused __MEMINIT* macros
  nilfs2: Constify struct kobj_type
  nilfs2: avoid undefined behavior in nilfs_cnt32_ge macro
  math: rational: add missing MODULE_DESCRIPTION() macro
  lib/zlib: add missing MODULE_DESCRIPTION() macro
  fs: ufs: add MODULE_DESCRIPTION()
  lib/rbtree.c: fix the example typo
  ocfs2: add bounds checking to ocfs2_check_dir_entry()
  fs: add kernel-doc comments to ocfs2_prepare_orphan_dir()
  coredump: simplify zap_process()
  selftests/fpu: add missing MODULE_DESCRIPTION() macro
  compiler.h: simplify data_race() macro
  build-id: require program headers to be right after ELF header
  resource: add missing MODULE_DESCRIPTION()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>math: rational: add missing MODULE_DESCRIPTION() macro</title>
<updated>2024-07-05T06:43:11+00:00</updated>
<author>
<name>Jeff Johnson</name>
<email>quic_jjohnson@quicinc.com</email>
</author>
<published>2024-07-02T22:47:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=8547d1150f0dbd1d04f397c780182fc83ec2ab16'/>
<id>8547d1150f0dbd1d04f397c780182fc83ec2ab16</id>
<content type='text'>
With ARCH=sh, make allmodconfig &amp;&amp; make W=1 C=1 reports: WARNING: modpost:
missing MODULE_DESCRIPTION() in lib/math/rational.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Link: https://lkml.kernel.org/r/20240702-md-sh-lib-math-v1-1-93f4ac4fa8fd@quicinc.com
Signed-off-by: Jeff Johnson &lt;quic_jjohnson@quicinc.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
With ARCH=sh, make allmodconfig &amp;&amp; make W=1 C=1 reports: WARNING: modpost:
missing MODULE_DESCRIPTION() in lib/math/rational.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.

Link: https://lkml.kernel.org/r/20240702-md-sh-lib-math-v1-1-93f4ac4fa8fd@quicinc.com
Signed-off-by: Jeff Johnson &lt;quic_jjohnson@quicinc.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lib/math: add missing MODULE_DESCRIPTION() macros</title>
<updated>2024-06-04T15:40:07+00:00</updated>
<author>
<name>Jeff Johnson</name>
<email>quic_jjohnson@quicinc.com</email>
</author>
<published>2024-06-01T05:21:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=0d618e39763e0e2b88586cd7d40ce8419735412f'/>
<id>0d618e39763e0e2b88586cd7d40ce8419735412f</id>
<content type='text'>
make allmodconfig &amp;&amp; make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/math/prime_numbers.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/math/rational-test.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson &lt;quic_jjohnson@quicinc.com&gt;
Link: https://lore.kernel.org/r/20240531-md-lib-math-v1-1-11a3bec51ebb@quicinc.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
make allmodconfig &amp;&amp; make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/math/prime_numbers.o
WARNING: modpost: missing MODULE_DESCRIPTION() in lib/math/rational-test.o

Add the missing invocations of the MODULE_DESCRIPTION() macro.

Signed-off-by: Jeff Johnson &lt;quic_jjohnson@quicinc.com&gt;
Link: https://lore.kernel.org/r/20240531-md-lib-math-v1-1-11a3bec51ebb@quicinc.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bitmap: introduce generic optimized bitmap_size()</title>
<updated>2024-04-01T09:49:28+00:00</updated>
<author>
<name>Alexander Lobakin</name>
<email>aleksander.lobakin@intel.com</email>
</author>
<published>2024-03-27T15:23:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=a37fbe666c016fd89e4460d0ebfcea05baba46dc'/>
<id>a37fbe666c016fd89e4460d0ebfcea05baba46dc</id>
<content type='text'>
The number of times yet another open coded
`BITS_TO_LONGS(nbits) * sizeof(long)` can be spotted is huge.
Some generic helper is long overdue.

Add one, bitmap_size(), but with one detail.
BITS_TO_LONGS() uses DIV_ROUND_UP(). The latter works well when both
divident and divisor are compile-time constants or when the divisor
is not a pow-of-2. When it is however, the compilers sometimes tend
to generate suboptimal code (GCC 13):

48 83 c0 3f          	add    $0x3f,%rax
48 c1 e8 06          	shr    $0x6,%rax
48 8d 14 c5 00 00 00 00	lea    0x0(,%rax,8),%rdx

%BITS_PER_LONG is always a pow-2 (either 32 or 64), but GCC still does
full division of `nbits + 63` by it and then multiplication by 8.
Instead of BITS_TO_LONGS(), use ALIGN() and then divide by 8. GCC:

8d 50 3f             	lea    0x3f(%rax),%edx
c1 ea 03             	shr    $0x3,%edx
81 e2 f8 ff ff 1f    	and    $0x1ffffff8,%edx

Now it shifts `nbits + 63` by 3 positions (IOW performs fast division
by 8) and then masks bits[2:0]. bloat-o-meter:

add/remove: 0/0 grow/shrink: 20/133 up/down: 156/-773 (-617)

Clang does it better and generates the same code before/after starting
from -O1, except that with the ALIGN() approach it uses %edx and thus
still saves some bytes:

add/remove: 0/0 grow/shrink: 9/133 up/down: 18/-538 (-520)

Note that we can't expand DIV_ROUND_UP() by adding a check and using
this approach there, as it's used in array declarations where
expressions are not allowed.
Add this helper to tools/ as well.

Reviewed-by: Przemek Kitszel &lt;przemyslaw.kitszel@intel.com&gt;
Acked-by: Yury Norov &lt;yury.norov@gmail.com&gt;
Signed-off-by: Alexander Lobakin &lt;aleksander.lobakin@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The number of times yet another open coded
`BITS_TO_LONGS(nbits) * sizeof(long)` can be spotted is huge.
Some generic helper is long overdue.

Add one, bitmap_size(), but with one detail.
BITS_TO_LONGS() uses DIV_ROUND_UP(). The latter works well when both
divident and divisor are compile-time constants or when the divisor
is not a pow-of-2. When it is however, the compilers sometimes tend
to generate suboptimal code (GCC 13):

48 83 c0 3f          	add    $0x3f,%rax
48 c1 e8 06          	shr    $0x6,%rax
48 8d 14 c5 00 00 00 00	lea    0x0(,%rax,8),%rdx

%BITS_PER_LONG is always a pow-2 (either 32 or 64), but GCC still does
full division of `nbits + 63` by it and then multiplication by 8.
Instead of BITS_TO_LONGS(), use ALIGN() and then divide by 8. GCC:

8d 50 3f             	lea    0x3f(%rax),%edx
c1 ea 03             	shr    $0x3,%edx
81 e2 f8 ff ff 1f    	and    $0x1ffffff8,%edx

Now it shifts `nbits + 63` by 3 positions (IOW performs fast division
by 8) and then masks bits[2:0]. bloat-o-meter:

add/remove: 0/0 grow/shrink: 20/133 up/down: 156/-773 (-617)

Clang does it better and generates the same code before/after starting
from -O1, except that with the ALIGN() approach it uses %edx and thus
still saves some bytes:

add/remove: 0/0 grow/shrink: 9/133 up/down: 18/-538 (-520)

Note that we can't expand DIV_ROUND_UP() by adding a check and using
this approach there, as it's used in array declarations where
expressions are not allowed.
Add this helper to tools/ as well.

Reviewed-by: Przemek Kitszel &lt;przemyslaw.kitszel@intel.com&gt;
Acked-by: Yury Norov &lt;yury.norov@gmail.com&gt;
Signed-off-by: Alexander Lobakin &lt;aleksander.lobakin@intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mul_u64_u64_div_u64: increase precision by conditionally swapping a and b</title>
<updated>2024-03-12T20:09:22+00:00</updated>
<author>
<name>Uwe Kleine-König</name>
<email>u.kleine-koenig@pengutronix.de</email>
</author>
<published>2024-03-03T09:24:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=8c86fb68ffcb0d8a5418e171c8d359d712912e9b'/>
<id>8c86fb68ffcb0d8a5418e171c8d359d712912e9b</id>
<content type='text'>
As indicated in the added comment, the algorithm works better if b is big.
As multiplication is commutative, a and b can be swapped.  Do this if a
is bigger than b.

Link: https://lkml.kernel.org/r/20240303092408.662449-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
Tested-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As indicated in the added comment, the algorithm works better if b is big.
As multiplication is commutative, a and b can be swapped.  Do this if a
is bigger than b.

Link: https://lkml.kernel.org/r/20240303092408.662449-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König &lt;u.kleine-koenig@pengutronix.de&gt;
Tested-by: Biju Das &lt;biju.das.jz@bp.renesas.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>lib/math/int_log: Replace LGPL-2.1-or-later boilerplate with SPDX identifier</title>
<updated>2023-07-09T21:47:50+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2023-07-03T13:52:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=9ab04d7ed8bdd395b0617a1647dd475681f99151'/>
<id>9ab04d7ed8bdd395b0617a1647dd475681f99151</id>
<content type='text'>
Replace license boilerplate in udftime.c with SPDX identifier for
LGPL-2.1-or-later.

Acked-by: Mauro Carvalho Chehab &lt;mchehab@kernel.org&gt;
Link: https://lore.kernel.org/r/20230619172019.21457-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20230703135211.87416-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replace license boilerplate in udftime.c with SPDX identifier for
LGPL-2.1-or-later.

Acked-by: Mauro Carvalho Chehab &lt;mchehab@kernel.org&gt;
Link: https://lore.kernel.org/r/20230619172019.21457-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20230703135211.87416-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
