The static inlines in bitmap.h do not handle a compile-time constant
nbits==0 correctly (they dereference the passed src or dst pointers,
despite only 0 words being valid to access). I had the 0-day buildbot
chew on a patch [1] that would cause build failures for such cases without
complaining, suggesting that we don't have any such users currently, at
least for the 70 .config/arch combinations that was built. Should any
turn up, make sure they use the out-of-line versions, which do handle
nbits==0 correctly.
This is of course not the most efficient, but it's much less churn than
teaching all the static inlines an "if (zero_const_nbits())", and since we
don't have any current instances, this doesn't affect existing code at
all.
[1] lkml.kernel.org/r/20180815085539.27485-1-linux@rasmusvillemoes.dk
Link: http://lkml.kernel.org/r/20180818131623.8755-3-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Yury Norov <ynorov@caviumnetworks.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A lot of code become ugly because of open coding allocations for bitmaps.
Introduce three helpers to allow users be more clear of intention
and keep their code neat.
Note, due to multiple circular dependencies we may not provide
the helpers as inliners. For now we keep them exported and, perhaps,
at some point in the future we will sort out header inclusion and
inheritance.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Commit 2a98dc028f ("include/linux/bitmap.h: turn bitmap_set and
bitmap_clear into memset when possible") introduced an optimization to
bitmap_{set,clear}() which uses memset() when the start and length are
constants aligned to a byte.
This is wrong on big-endian systems; our bitmaps are arrays of unsigned
long, so bit n is not at byte n / 8 in memory. This was caught by the
Btrfs selftests, but the bitmap selftests also fail when run on a
big-endian machine.
We can still use memset if the start and length are aligned to an
unsigned long, so do that on big-endian. The same problem applies to
the memcmp in bitmap_equal(), so fix it there, too.
Fixes: 2a98dc028f ("include/linux/bitmap.h: turn bitmap_set and bitmap_clear into memset when possible")
Fixes: 2c6deb0152 ("bitmap: use memcmp optimisation in more situations")
Cc: stable@kernel.org
Reported-by: "Erhard F." <erhard_f@mailbox.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset replaces bitmap_{to,from}_u32array with more simple and
standard looking copy-like functions.
bitmap_from_u32array() takes 4 arguments (bitmap_to_u32array is similar):
- unsigned long *bitmap, which is destination;
- unsigned int nbits, the length of destination bitmap, in bits;
- const u32 *buf, the source; and
- unsigned int nwords, the length of source buffer in ints.
In description to the function it is detailed like:
* copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining
* bits between nword and nbits in @bitmap (if any) are cleared.
Having two size arguments looks unneeded and potentially dangerous.
It is unneeded because normally user of copy-like function should take
care of the size of destination and make it big enough to fit source
data.
And it is dangerous because function may hide possible error if user
doesn't provide big enough bitmap, and data becomes silently dropped.
That's why all copy-like functions have 1 argument for size of copying
data, and I don't see any reason to make bitmap_from_u32array()
different.
One exception that comes in mind is strncpy() which also provides size
of destination in arguments, but it's strongly argued by the possibility
of taking broken strings in source. This is not the case of
bitmap_{from,to}_u32array().
There is no many real users of bitmap_{from,to}_u32array(), and they all
very clearly provide size of destination matched with the size of
source, so additional functionality is not used in fact. Like this:
bitmap_from_u32array(to->link_modes.supported,
__ETHTOOL_LINK_MODE_MASK_NBITS,
link_usettings.link_modes.supported,
__ETHTOOL_LINK_MODE_MASK_NU32);
Where:
#define __ETHTOOL_LINK_MODE_MASK_NU32 \
DIV_ROUND_UP(__ETHTOOL_LINK_MODE_MASK_NBITS, 32)
In this patch, bitmap_copy_safe and bitmap_{from,to}_arr32 are introduced.
'Safe' in bitmap_copy_safe() stands for clearing unused bits in bitmap
beyond last bit till the end of last word. It is useful for hardening
API when bitmap is assumed to be exposed to userspace.
bitmap_{from,to}_arr32 functions are replacements for
bitmap_{from,to}_u32array. They don't take unneeded nwords argument, and
so simpler in implementation and understanding.
This patch suggests optimization for 32-bit systems - aliasing
bitmap_{from,to}_arr32 to bitmap_copy_safe.
Other possible optimization is aliasing 64-bit LE bitmap_{from,to}_arr32 to
more generic function(s). But I didn't end up with the function that would
be helpful by itself, and can be used to alias 64-bit LE
bitmap_{from,to}_arr32, like bitmap_copy_safe() does. So I preferred to
leave things as is.
The following patch switches kernel to new API and introduces test for it.
Discussion is here: https://lkml.org/lkml/2017/11/15/592
[ynorov@caviumnetworks.com: rename bitmap_copy_safe to bitmap_copy_clear_tail]
Link: http://lkml.kernel.org/r/20180201172508.5739-3-ynorov@caviumnetworks.com
Link: http://lkml.kernel.org/r/20171228150019.27953-1-ynorov@caviumnetworks.com
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: David Decotigny <decot@googlers.com>,
Cc: David S. Miller <davem@davemloft.net>,
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull documentation updates from Jonathan Corbet:
"A relatively calm cycle for the docs tree again.
- The old driver statement has been added to the kernel docs.
- We have a couple of new helper scripts. find-unused-docs.sh from
Sayli Karnic will point out kerneldoc comments that are not actually
used in the documentation. Jani Nikula's
documentation-file-ref-check finds references to non-existing files.
- A new ftrace document from Steve Rostedt.
- Vinod Koul converted the dmaengine docs to RST
Beyond that, it's mostly simple fixes.
This set reaches outside of Documentation/ a bit more than most. In
all cases, the changes are to comment docs, mostly from Randy, in
places where there didn't seem to be anybody better to take them"
* tag 'docs-4.15' of git://git.lwn.net/linux: (52 commits)
documentation: fb: update list of available compiled-in fonts
MAINTAINERS: update DMAengine documentation location
dmaengine: doc: ReSTize pxa_dma doc
dmaengine: doc: ReSTize dmatest doc
dmaengine: doc: ReSTize client API doc
dmaengine: doc: ReSTize provider doc
dmaengine: doc: Add ReST style dmaengine document
ftrace/docs: Add documentation on how to use ftrace from within the kernel
bug-hunting.rst: Fix an example and a typo in a Sphinx tag
scripts: Add a script to find unused documentation
samples: Convert timers to use timer_setup()
documentation: kernel-api: add more info on bitmap functions
Documentation: fix selftests related file refs
Documentation: fix ref to power basic-pm-debugging
Documentation: fix ref to trace stm content
Documentation: fix ref to coccinelle content
Documentation: fix ref to workqueue content
Documentation: fix ref to sphinx/kerneldoc.py
Documentation: fix locking rt-mutex doc refs
docs: dev-tools: correct Coccinelle version number
...
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 <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 <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are some good comments about bitmap operations in lib/bitmap.c
and include/linux/bitmap.h, so format them for document generation and
pull them into core-api/kernel-api.rst.
I converted the "tables" of functions from using tabs to using spaces
so that they are more readable in the source file and in the generated
output.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
The bitmap_equal function has optimized code for small bitmaps with less
than BITS_PER_LONG bits. For larger bitmaps the out-of-line function
__bitmap_equal is called.
For a constant number of bits divisible by BITS_PER_LONG the memcmp
function can be used. For s390 gcc knows how to optimize this function,
memcmp calls with up to 256 bytes / 2048 bits are translated into a
single instruction.
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Aimed at transferring bitmaps to/from user-space in a 32/64-bit agnostic
way.
Tested:
unit tests (next patch) on qemu i386, x86_64, ppc, ppc64 BE and LE,
ARM.
Signed-off-by: David Decotigny <decot@googlers.com>
Reviewed-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
The macro BITMAP_LAST_WORD_MASK can be implemented without a conditional,
which will generally lead to slightly better generated code (221 bytes
saved for allmodconfig-GCOV_KERNEL, ~2k with GCOV_KERNEL). As a small
bonus, this also ensures that the nbits parameter is expanded exactly
once.
In BITMAP_FIRST_WORD_MASK, if start is signed gcc is technically allowed
to assume it is positive (or divisible by BITS_PER_LONG), and hence just
do the simple mask. It doesn't seem to use this, and even on an
architecture like x86 where the shift only depends on the lower 5 or 6
bits, and these bits are not affected by the signedness of the expression,
gcc still generates code to compute the C99 mandated value of start %
BITS_PER_LONG. So just use a mask explicitly, also for consistency with
BITMAP_LAST_WORD_MASK.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Reviewed-by: George Spelvin <linux@horizon.com>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
